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Sample records for wall polysaccharide composition

  1. Structural analysis of cell wall polysaccharides using PACE

    Energy Technology Data Exchange (ETDEWEB)

    Mortimer, Jennifer C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Institute

    2017-01-01

    The plant cell wall is composed of many complex polysaccharides. The composition and structure of the polysaccharides affect various cell properties including cell shape, cell function and cell adhesion. Many techniques to characterize polysaccharide structure are complicated, requiring expensive equipment and specialized operators e.g. NMR, MALDI-MS. PACE (Polysaccharide Analysis using Carbohydrate gel Electrophoresis) uses a simple, rapid technique to analyze polysaccharide quantity and structure (Goubet et al. 2002). Whilst the method here describes xylan analysis, it can be applied (by use of the appropriate glycosyl hydrolase) to any cell wall polysaccharide.

  2. Quantitative Prediction of Cell Wall Polysaccharide Composition in Grape (Vitis vinifera L.) and Apple (Malus domestica) Skins from Acid Hydrolysis Monosaccharide Profiles

    DEFF Research Database (Denmark)

    Arnous, Anis; Meyer, Anne S.

    2009-01-01

    On the basis of monosaccharide analysis after acid hydrolysis of fruit skin samples of three wine grape cultivars, Vitis vinifera L. Cabernet Sauvignon, Merlot, and Shiraz, and of two types of apple, Malus domestica Red Delicious and Golden Delicious, an iterative calculation method is reported...... for the quantitative allocation of plant cell wall monomers into relevant structural polysaccharide elements. By this method the relative molar distribution (mol %) of the different polysaccharides in the red wine grape skins was estimated as 57-62 mol % homogalacturonan, 6.0-14 mol % cellulose, 10-11 mol % xyloglucan......, 7 mol % arabinan, 4.5-5.0 mol % rhamnogalacturonan I, 3.5-4.0 mol % rhamnogalacturonan II, 3 mol % arabinogalactan, and 0.5-1.0 mol % mannans; the ranges indicate minor variations in the skin composition of the three different cultivars. These cell wall polysaccharides made up similar to 43...

  3. The Specific Nature of Plant Cell Wall Polysaccharides 1

    Science.gov (United States)

    Nevins, Donald J.; English, Patricia D.; Albersheim, Peter

    1967-01-01

    Polysaccharide compositions of cell walls were assessed by quantitative analyses of the component sugars. Cell walls were hydrolyzed in 2 n trifluoroacetic acid and the liberated sugars reduced to their respective alditols. The alditols were acetylated and the resulting alditol acetates separated by gas chromatography. Quantitative assay of the alditol acetates was accomplished by electronically integrating the detector output of the gas chromatograph. Myo-inositol, introduced into the sample prior to hydrolysis, served as an internal standard. The cell wall polysaccharide compositions of plant varieties within a given species are essentially identical. However, differences in the sugar composition were observed in cell walls prepared from different species of the same as well as of different genera. The fact that the wall compositions of different varieties of the same species are the same indicates that the biosynthesis of cell wall polysaccharides is genetically regulated. The cell walls of various morphological parts (roots, hypocotyls, first internodes and primary leaves) of bean plants were each found to have a characteristic sugar composition. It was found that the cell wall sugar composition of suspension-cultured sycamore cells could be altered by growing the cells on different carbon sources. This demonstrates that the biosynthesis of cell wall polysaccharides can be manipulated without fatal consequences. PMID:16656594

  4. Influence of cultivar, cooking, and storage on cell-wall polysaccharide composition of winter squash (Cucurbita maxima).

    Science.gov (United States)

    Ratnayake, R M Sunil; Melton, Laurence D; Hurst, Paul L

    2003-03-26

    Changes in the cell-wall polysaccharides (CWP) of the edible tissues of four winter squash cultivars during storage and after cooking were investigated. A procedure for isolating cell walls of tissues containing high levels of starch was used. The starch-free CWP were sequentially fractionated using CDTA, dilute Na(2)CO(3), and 4 M KOH. Cellulose made up 40-42% of the total CWP for three cultivars (Delica, CF 2, and CF 4) at harvest but was 35% in the softer Red Warren. The pectic polysaccharides of Delica, CF 2, and CF 4 cell walls are more branched than those from Red Warren squash. The higher proportion of uronic acid in the pectic polysaccharides of Red Warren squash correlates with its lower firmness. Cooking resulted in an increase in the water-soluble pectins and a decrease in the pectins associated with cellulose. The total CWP content of the squash cultivars remained unchanged for up to 2 months of storage and then markedly decreased between 2 and 3 months of storage. The galactose content of Delica and Red Warren cell walls remained relatively constant from harvest to 2 months of storage and then decreased markedly during 2-3 months of storage.

  5. Unexpected features of exponentially growing Tobacco Bright Yellow-2 cell suspension culture in relation to excreted extracellular polysaccharides and cell wall composition.

    Science.gov (United States)

    Issawi, Mohammad; Muhieddine, Mohammad; Girard, Celine; Sol, Vincent; Riou, Catherine

    2017-10-01

    This article presents a new insight about TBY-2 cells; from extracellular polysaccharides secretion to cell wall composition during cell suspension culture. In the medium of cells taken 2 days after dilution (end of lag phase), a two unit pH decrease from 5.38 to 3.45 was observed and linked to a high uronic acid (UA) amount secretion (47.8%) while, in 4 and 7 day-old spent media, pH increased and UA amounts decreased 35.6 and 42.3% UA, respectively. To attain deeper knowledge of the putative link between extracellular polysaccharide excretion and cell wall composition, we determined cell wall UA and neutral sugar composition of cells from D2 to D12 cultures. While cell walls from D2 and D3 cells contained a large amount of uronic acid (twice as much as the other analysed cell walls), similar amounts of neutral sugar were detected in cells from lag to end of exponential phase cells suggesting an enriched pectin network in young cultures. Indeed, monosaccharide composition analysis leads to an estimated percentage of pectins of 56% for D3 cell wall against 45% D7 cell walls indicating that the cells at the mid-exponential growth phase re-organized their cell wall linked to a decrease in secreted UA that finally led to a stabilization of the spent medium pH to 5.4. In conclusion, TBY-2 cell suspension from lag to stationary phase showed cell wall remodeling that could be of interest in drug interaction and internalization study.

  6. Plant cell wall polysaccharide analysis during cell elongation

    DEFF Research Database (Denmark)

    Guo, Xiaoyuan

    Plant cell walls are complex structures whose composition and architecture are important to various cellular activities. Plant cell elongation requires a high level of rearrangement of the cell wall polymers to enable cell expansion. However, the cell wall polysaccharides dynamics during plant cell...... elongation is poorly understood. This PhD project aims to elucidate the cell wall compositional and structural change during cell elongation by using Comprehensive Microarray Polymer Profiling (CoMPP), microscopic techniques and molecular modifications of cell wall polysaccharide. Developing cotton fibre......, pea and Arabidopsis thaliana were selected as research models to investigate different types of cell elongation, developmental elongation and tropism elongation. A set of comprehensive analysis covering 4 cotton species and 11 time points suggests that non-cellulosic polysaccharides contribute...

  7. Composition and architecture of the cell walls of grasses and the mechanisms of synthesis of cell wall polysaccharides. Final report for period September 1, 1988 - April 30, 2001

    Energy Technology Data Exchange (ETDEWEB)

    Carpita, Nicholas C.

    2001-10-18

    This program was devoted toward complete understanding of the polysaccharide structure and architecture of the primary cell walls grasses and cereals, and the biosynthesis of the mixed-linkage beta-glucane, a cellulose interacting polymer that is synthesized uniquely by grass species and close relatives. With these studies as focal point, the support from DOE was instrumental in the development of new analytical means that enabled us to characterize carbohydrate structure, to reveal new features of cell wall dynamics during cell growth, and to apply these techniques in other model organisms. The support by DOE in these basic studies was acknowledged on numerous occasions in review articles covering current knowledge of cell wall structure, architecture, dynamics, biosynthesis, and in all genes related to cell wall biogenesis.

  8. Changes in Cell Wall Polysaccharides Associated With Growth 1

    Science.gov (United States)

    Nevins, Donald J.; English, Patricia D.; Albersheim, Peter

    1968-01-01

    Changes in the polysaccharide composition of Phaseolus vulgaris, P. aureus, and Zea mays cell walls were studied during the first 28 days of seedling development using a gas chromatographic method for the analysis of neutral sugars. Acid hydrolysis of cell wall material from young tissues liberates rhamnose, fucose, arabinose, xylose, mannose, galactose, and glucose which collectively can account for as much as 70% of the dry weight of the wall. Mature walls in fully expanded tissues of these same plants contain less of these constituents (10%-20% of dry wt). Gross differences are observed between developmental patterns of the cell wall in the various parts of a seedling, such as root, stem, and leaf. The general patterns of wall polysaccharide composition change, however, are similar for analogous organs among the varieties of a species. Small but significant differences in the rates of change in sugar composition were detected between varieties of the same species which exhibited different growth patterns. The cell walls of species which are further removed phylogenetically exhibit even more dissimilar developmental patterns. The results demonstrate the dynamic nature of the cell wall during growth as well as the quantitative and qualitative exactness with which the biosynthesis of plant cell walls is regulated. PMID:16656862

  9. Cell-wall polysaccharide composition and glycanase activity of Silene vulgaris callus transformed with rolB and rolC genes.

    Science.gov (United States)

    Günter, Elena A; Shkryl, Yury N; Popeyko, Oxana V; Veremeichik, Galina N; Bulgakov, Victor P

    2015-03-15

    The aim of this research is to investigate the effects of the Agrobacterium rhizogenes rol genes on the composition of cell-wall polysaccharides and glycanase activity in the campion callus. The expression of the rolC gene reduces the yield of campion pectin, while the expression of the rolB or rolC gene inhibits the volumetric production of both pectin and intracellular arabinogalactan. The rol genes are involved in regulating the activity of glycanases and esterases, thereby contributing to the modification of polysaccharide structures, their molecular weight (Mw) and the degree of pectin methyl esterification (DE). The increase in pectin arabinose residue appears to be connected to a decrease in intracellular and extracellular α-l-arabinofuranosidase activity in transgenic campion calluses. In transgenic calluses expressing the rolB and rolC genes, the increase in pectin galactose residue is likely due to a decrease in β-galactosidase activity. The decrease in the Mw of pectin and its d-galacturonic acid content appears to be connected to an increase in extracellular polygalacturonase activity. Finally, the increase in pectinesterase activity causes a decrease in the DE of pectin. Thus, the expression of rolB and rolC genes in campion callus has a considerable effect on pectin's sugar composition, DE and Mw, while it appears to have an insignificant influence on intracellular and extracellular arabinogalactans. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Immunogold scanning electron microscopy can reveal the polysaccharide architecture of xylem cell walls

    Science.gov (United States)

    Sun, Yuliang; Juzenas, Kevin

    2017-01-01

    Abstract Immunofluorescence microscopy (IFM) and immunogold transmission electron microscopy (TEM) are the two main techniques commonly used to detect polysaccharides in plant cell walls. Both are important in localizing cell wall polysaccharides, but both have major limitations, such as low resolution in IFM and restricted sample size for immunogold TEM. In this study, we have developed a robust technique that combines immunocytochemistry with scanning electron microscopy (SEM) to study cell wall polysaccharide architecture in xylem cells at high resolution over large areas of sample. Using multiple cell wall monoclonal antibodies (mAbs), this immunogold SEM technique reliably localized groups of hemicellulosic and pectic polysaccharides in the cell walls of five different xylem structures (vessel elements, fibers, axial and ray parenchyma cells, and tyloses). This demonstrates its important advantages over the other two methods for studying cell wall polysaccharide composition and distribution in these structures. In addition, it can show the three-dimensional distribution of a polysaccharide group in the vessel lateral wall and the polysaccharide components in the cell wall of developing tyloses. This technique, therefore, should be valuable for understanding the cell wall polysaccharide composition, architecture and functions of diverse cell types. PMID:28398585

  11. Enzymatic Modification of Plant Cell Wall Polysaccharides

    DEFF Research Database (Denmark)

    Øbro, Jens; Hayashi, Takahisa; Mikkelsen, Jørn Dalgaard

    2011-01-01

    Plant cell walls are intricate structures with remarkable properties, widely used in almost every aspect of our life. Cell walls consist largely of complex polysaccharides and there is often a need for chemical and biochemical processing before industrial use. There is an increasing demand...... for sustainable processes that replace chemical treatments with white biotechnology. Plants can contribute significantly to this sustainable process by producing plant or microbialenzymes in planta that are necessary for plant cell wall modification or total degradation. This will give rise to superior food...... fibres, hydrocolloids, paper,textile, animal feeds or biofuels. Classical microbial-based fermentation systems could in the future face serious competition from plant-based expression systems for enzyme production. Plant expressed enzymes can either be targeted to specific cellular compartments...

  12. Composition and architecture of the cell walls of grasses and the mechanisms of synthesis of cell wall polysaccharides. Final report for period September 1, 1988 - April 30, 2001; FINAL

    International Nuclear Information System (INIS)

    Carpita, Nicholas C.

    2001-01-01

    This program was devoted toward complete understanding of the polysaccharide structure and architecture of the primary cell walls grasses and cereals, and the biosynthesis of the mixed-linkage beta-glucane, a cellulose interacting polymer that is synthesized uniquely by grass species and close relatives. With these studies as focal point, the support from DOE was instrumental in the development of new analytical means that enabled us to characterize carbohydrate structure, to reveal new features of cell wall dynamics during cell growth, and to apply these techniques in other model organisms. The support by DOE in these basic studies was acknowledged on numerous occasions in review articles covering current knowledge of cell wall structure, architecture, dynamics, biosynthesis, and in all genes related to cell wall biogenesis

  13. The digestion of yeast cell wall polysaccharides in veal calves

    NARCIS (Netherlands)

    Gaillard, B.D.E.; Weerden, van E.J.

    1976-01-01

    1. The digestibility of the cell wall polysaccharides of an alkane-grown yeast in different parts of the digestive tract of two veal calves fitted with re-entrant cannulas at the end of the ileum was studied by replacing part of the skim-milk powder of their ‘normal’, milk-substitute

  14. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria.

    Science.gov (United States)

    Mistou, Michel-Yves; Sutcliffe, Iain C; van Sorge, Nina M

    2016-07-01

    The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. © FEMS 2016.

  15. Antioxidant properties of cell wall polysaccharides of Stevia rebaudiana leaves

    Directory of Open Access Journals (Sweden)

    Mediesse Kengne Francine

    2014-12-01

    Full Text Available Objective: To examine the total phenolic and protein contents, and the antioxidant activities of cell wall polysaccharide fractions of Stevia rebaudiana leaves. Methods: Three different polysaccharide-enriched fractions, namely FPE (extract with 50 mmol/ L ethylene diamine tetra acetic acid, FPK (extract with 0.05 mol/L KOH and FH (extract with 4 mol/L KOH were extracted from Stevia rebaudiana leaves. The antioxidant activity of these fractions was evaluated based on their ability to scavenge DPPH (1, 1-diphenyl-2-picryl hydrazyl free radical, to reduce ferric power, to chelate ferrous ion and to protect human DNA. Results: The results indicated that protein content was found to be higher in FPK polysaccharide enriched fraction (47.48 µg per mg of FPK. Furthermore, the phenolic compound analysis according to the Folin-Ciocalteu method was higher in FPK (17.71 µg ferulic acid. The DPPH maximal inhibition percentage of the three polysaccharide-enriched fractions at 400 µg/mL was 27.66%, 59.90% and 23.21% respectively for FPE, FPK and FH. All the polysaccharide fractions exhibited a ferric reducing power except the FH one. The three fractions also exhibited lipid peroxidation inhibition, and they completely reverted the DNA damage induced by H2O2/FeCl2. FPK showed the strongest scavenging activity against the DPPH radical, the best chelating ability and lipid peroxidation inhibition. Conclusions: Stevia cell wall polysaccharide fractions are potent protective agents against oxidative stress. The analysis revealed major differences in the antioxidant activity in the three polysaccharides fractions. However, the 0.05 mol/L KOH pectin fraction (FPK showed better antioxidant activity.

  16. Neisseria meningitidis serogroup A capsular polysaccharide acetyltransferase, methods and compositions

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, David S [Stone Mountain, GA; Gudlavalleti, Seshu K [Kensington, MD; Tzeng, Yih-Ling [Atlanta, GA; Datta, Anup K [San Diego, CA; Carlson, Russell W [Athens, GA

    2011-02-08

    Provided are methods for recombinant production of an O-acetyltransferase and methods for acetylating capsular polysaccharides, especially those of a Serogroup A Neisseria meningitidis using the recombinant O-acetyltransferase, and immunogenic compositions comprising the acetylated capsular polysaccharide.

  17. Small molecule probes for plant cell wall polysaccharide imaging

    Directory of Open Access Journals (Sweden)

    Ian eWallace

    2012-05-01

    Full Text Available Plant cell walls are composed of interlinked polymer networks consisting of cellulose, hemicelluloses, pectins, proteins, and lignin. The ordered deposition of these components is a dynamic process that critically affects the development and differentiation of plant cells. However, our understanding of cell wall synthesis and remodeling, as well as the diverse cell wall architectures that result from these processes, has been limited by a lack of suitable chemical probes that are compatible with live-cell imaging. In this review, we summarize the currently available molecular toolbox of probes for cell wall polysaccharide imaging in plants, with particular emphasis on recent advances in small molecule-based fluorescent probes. We also discuss the potential for further development of small molecule probes for the analysis of cell wall architecture and dynamics.

  18. Genetic engineering of grass cell wall polysaccharides for biorefining.

    Science.gov (United States)

    Bhatia, Rakesh; Gallagher, Joe A; Gomez, Leonardo D; Bosch, Maurice

    2017-09-01

    Grasses represent an abundant and widespread source of lignocellulosic biomass, which has yet to fulfil its potential as a feedstock for biorefining into renewable and sustainable biofuels and commodity chemicals. The inherent recalcitrance of lignocellulosic materials to deconstruction is the most crucial limitation for the commercial viability and economic feasibility of biomass biorefining. Over the last decade, the targeted genetic engineering of grasses has become more proficient, enabling rational approaches to modify lignocellulose with the aim of making it more amenable to bioconversion. In this review, we provide an overview of transgenic strategies and targets to tailor grass cell wall polysaccharides for biorefining applications. The bioengineering efforts and opportunities summarized here rely primarily on (A) reprogramming gene regulatory networks responsible for the biosynthesis of lignocellulose, (B) remodelling the chemical structure and substitution patterns of cell wall polysaccharides and (C) expressing lignocellulose degrading and/or modifying enzymes in planta. It is anticipated that outputs from the rational engineering of grass cell wall polysaccharides by such strategies could help in realizing an economically sustainable, grass-derived lignocellulose processing industry. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  19. Sugar Composition and Molecular Weight Distribution of Cell Wall Polysaccharides in Outer and Inner Tissues from Segments of Dark Grown Squash (Cucurbita maxima Duch.) Hypocotyls.

    Science.gov (United States)

    Wakabayashi, K; Sakurai, N; Kuraishi, S

    1990-07-01

    The elongation growth of stem segments is determined by the outer cell layers (epidermis and collenchyma). We measured the sugar composition and molecular weight distribution of pectin and hemicellulose fractions obtained from inner and outer tissues of squash (Cucurbita maxima Duch.) hypocotyls. In addition, we studied the changes in these parameters after a 9 hour period of incubation of the segments. The results show that outer tissues have higher molecular weight pectin and hemicellulose compared to inner tissues (2-3 times higher). Incubation results in a 13 to 25% decrease in the amount of pectin and hemicellulose in inner tissues and an increase of 11 to 32% in the outer tissues. This increase in the outer tissues is accompanied by a decrease in the molecular weight of some of the components. These results clearly show that cell wall metabolism during elongation growth differs markedly in inner and outer tissues, and that future studies on the effect of auxin need to take these differences into account.

  20. Sugar Composition and Molecular Weight Distribution of Cell Wall Polysaccharides in Outer and Inner Tissues from Segments of Dark Grown Squash (Cucurbita maxima Duch.) Hypocotyls 1

    Science.gov (United States)

    Wakabayashi, Kazuyuki; Sakurai, Naoki; Kuraishi, Susumu

    1990-01-01

    The elongation growth of stem segments is determined by the outer cell layers (epidermis and collenchyma). We measured the sugar composition and molecular weight distribution of pectin and hemicellulose fractions obtained from inner and outer tissues of squash (Cucurbita maxima Duch.) hypocotyls. In addition, we studied the changes in these parameters after a 9 hour period of incubation of the segments. The results show that outer tissues have higher molecular weight pectin and hemicellulose compared to inner tissues (2-3 times higher). Incubation results in a 13 to 25% decrease in the amount of pectin and hemicellulose in inner tissues and an increase of 11 to 32% in the outer tissues. This increase in the outer tissues is accompanied by a decrease in the molecular weight of some of the components. These results clearly show that cell wall metabolism during elongation growth differs markedly in inner and outer tissues, and that future studies on the effect of auxin need to take these differences into account. PMID:16667612

  1. Targeted and non-targeted effects in cell wall polysaccharides from transgenetically modified potato tubers

    NARCIS (Netherlands)

    Huang, J.H.

    2016-01-01

    The plant cell wall is a chemically complex network composed mainly of polysaccharides. Cell wall polysaccharides surround and protect plant cells and are responsible for the stability and rigidity of plant tissue. Pectin is a major component of primary cell wall and the middle lamella of plants.

  2. Exploring the Role of Cell Wall-Related Genes and Polysaccharides during Plant Development.

    Science.gov (United States)

    Tucker, Matthew R; Lou, Haoyu; Aubert, Matthew K; Wilkinson, Laura G; Little, Alan; Houston, Kelly; Pinto, Sara C; Shirley, Neil J

    2018-05-31

    The majority of organs in plants are not established until after germination, when pluripotent stem cells in the growing apices give rise to daughter cells that proliferate and subsequently differentiate into new tissues and organ primordia. This remarkable capacity is not only restricted to the meristem, since maturing cells in many organs can also rapidly alter their identity depending on the cues they receive. One general feature of plant cell differentiation is a change in cell wall composition at the cell surface. Historically, this has been viewed as a downstream response to primary cues controlling differentiation, but a closer inspection of the wall suggests that it may play a much more active role. Specific polymers within the wall can act as substrates for modifications that impact receptor binding, signal mobility, and cell flexibility. Therefore, far from being a static barrier, the cell wall and its constituent polysaccharides can dictate signal transmission and perception, and directly contribute to a cell's capacity to differentiate. In this review, we re-visit the role of plant cell wall-related genes and polysaccharides during various stages of development, with a particular focus on how changes in cell wall machinery accompany the exit of cells from the stem cell niche.

  3. Structure, cell wall elasticity and polysaccharide properties of living yeast cells, as probed by AFM

    International Nuclear Information System (INIS)

    Alsteens, David; Dupres, Vincent; Evoy, Kevin Mc; Dufrene, Yves F; Wildling, Linda; Gruber, Hermann J

    2008-01-01

    Although the chemical composition of yeast cell walls is known, the organization, assembly, and interactions of the various macromolecules remain poorly understood. Here, we used in situ atomic force microscopy (AFM) in three different modes to probe the ultrastructure, cell wall elasticity and polymer properties of two brewing yeast strains, i.e. Saccharomyces carlsbergensis and S. cerevisiae. Topographic images of the two strains revealed smooth and homogeneous cell surfaces, and the presence of circular bud scars on dividing cells. Nanomechanical measurements demonstrated that the cell wall elasticity of S. carlsbergensis is homogeneous. By contrast, the bud scar of S. cerevisiae was found to be stiffer than the cell wall, presumably due to the accumulation of chitin. Notably, single molecule force spectroscopy with lectin-modified tips revealed major differences in polysaccharide properties of the two strains. Polysaccharides were clearly more extended on S. cerevisiae, suggesting that not only oligosaccharides, but also polypeptide chains of the mannoproteins were stretched. Consistent with earlier cell surface analyses, these findings may explain the very different aggregation properties of the two organisms. This study demonstrates the power of using multiple complementary AFM modalities for probing the organization and interactions of the various macromolecules of microbial cell walls

  4. Polysaccharide composition of raw and cooked chayote (Sechium edule Sw.) fruits and tuberous roots.

    Science.gov (United States)

    Shiga, Tânia M; Peroni-Okita, Fernanda Helena Gonçalves; Carpita, Nicholas C; Lajolo, Franco Maria; Cordenunsi, Beatriz Rosana

    2015-10-05

    Chayote is a multipurpose table vegetable widely consumed in Latin America countries. Chayote fruits, leaves and tuberous roots contain complex carbohydrates as dietary fiber and starch, vitamins and minerals. The complex polysaccharides (cell walls and starch) were analyzed in the black and green varieties of chayote fruits as well as in green chayote tuberous root before and after a controlled cooking process to assess changes in their composition and structure. The monosaccharide composition and linkage analysis indicated pectins homogalacturonans and rhamnogalacturonan I backbones constitute about 15-20% of the wall mass, but are heavily substituted with, up to 60% neutral arabinans, galactans, arabinogalactans. The remainder is composed of xyloglucan, glucomannans and galactoglucomannans. Chayote cell-wall polysaccharides are highly stable under normal cooking conditions, as confirmed by the optical microscopy of wall structure. We found also that tuberous roots constitute a valuable additional source of quality starch and fiber. Published by Elsevier Ltd.

  5. Maca polysaccharides: A review of compositions, isolation, therapeutics and prospects.

    Science.gov (United States)

    Li, Yujuan; Xu, Fangxue; Zheng, Mengmeng; Xi, Xiaozhi; Cui, Xiaowei; Han, Chunchao

    2018-05-01

    Maca polysaccharides, some of the major bioactive substances in Lepidium meyenii (Walp.) (Maca), have various biological properties, including anti-oxidant, anti-fatigue, anti-tumor, and immunomodulatory effects, as well as hepatoprotective activity and regulation function. Although many therapeutics depend on multiple structures of maca polysaccharides in addition to providing sufficient foundations for maca polysaccharide products in industrial applications, the relationships between the pharmacological effects and structures have not been established. Therefore, this article summarizes the extraction and purification methods, compositions, pharmacological effects, prospects and industrial applications of maca polysaccharides. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Effects of cooking on the cell walls (dietary fiber) of 'Scarlet Warren' winter squash ( Cucurbita maxima ) studied by polysaccharide linkage analysis and solid-state (13)C NMR.

    Science.gov (United States)

    Ratnayake, R M Sunil; Sims, Ian M; Newman, Roger H; Melton, Laurence D

    2011-07-13

    Cell wall polysaccharides of 'Scarlet Warren' winter squash ( Cucurbita maxima ) were investigated before and after thermal processing. Linkage analysis of polysaccharides was done by gas chromatography coupled to mass spectrometry (GC-MS). The linkage analysis showed the cell wall polysaccharide compositions of raw and cooked squash were similar. The total pectic polysaccharides (galacturonan, rhamnogalacturonan, arabinan, and arabinogalactan) contents of the cell walls of both raw and cooked squash were 39 mol %. The amounts of pectic polysaccharides and xyloglucan in the cell walls of squash showed little alteration on heating. The cellulose content of the raw and cooked cell walls was relatively high at 47 mol %, whereas the xyloglucan content was low at 4 mol %. Solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy techniques were used to examine the molecular motion of the polysaccharides in the cell walls. The mobility of highly flexible galactan depends on the water content of the sample, but no difference was seen between raw and cooked samples. Likewise, the mobility of semimobile pectic polysaccharides was apparently unaltered by cooking. No change was detected in the rigid cellulose microfibrils on cooking.

  7. Fermentation characteristics of polysaccharide fractions extracted from the cell walls of maize endosperm

    NARCIS (Netherlands)

    Laar, van H.; Tamminga, S.; Williams, B.A.; Verstegen, M.W.A.; Schols, H.A.

    2002-01-01

    Cell walls were extracted from maize endosperm and separated into different polysaccharide fractions by sequential extraction with solutions of saturated Ba(OH)2, demineralised water and 1 and 4 M KOH. Solubilised polysaccharides were collected after each extraction. Residues were collected

  8. Purification, structure and immunobiological activity of an arabinan-rich pectic polysaccharide from the cell walls of Prunus dulcis seeds.

    Science.gov (United States)

    Dourado, Fernando; Madureira, Pedro; Carvalho, Vera; Coelho, Ricardo; Coimbra, Manuel A; Vilanova, Manuel; Mota, Manuel; Gama, Francisco M

    2004-10-20

    The structure and bioactivity of a polysaccharide extracted and purified from a 4M KOH + H3BO3 solution from Prunus dulcis seed cell wall material was studied. Anion-exchange chromatography of the crude extract yielded two sugar-rich fractions: one neutral (A), the other acidic (E). These fractions contain a very similar monosaccharide composition: 5:2:1 for arabinose, uronic acids and xylose, respectively, rhamnose and galactose being present in smaller amounts. As estimated by size-exclusion chromatography, the acidic fraction had an apparent molecular mass of 762 kDa. Methylation analysis (from the crude and fractions A and E), suggests that the polysaccharide is an arabinan-rich pectin. In all cases, the polysaccharides bear the same type of structural Ara moieties with highly branched arabinan-rich pectic polysaccharides. The average relative proportions of the arabinosyl linkages is 3:2:1:1 for T-Araf:(1-->5)-Araf:(1-->3,5)-Araf:(1-->2,3,5)-Araf. The crude polysaccharide extract and fractions A and E induced a murine lymphocyte stimulatory effect, as evaluated by the in vitro and in vivo expression of lymphocyte activation markers and spleen mononuclear cells culture proliferation. The lymphocyte stimulatory effect was stronger on B- than on T-cells. No evidence of cytotoxic effects induced by the polysaccharide fractions was found.

  9. Interfaces study of all-polysaccharide composite films

    Czech Academy of Sciences Publication Activity Database

    Šimkovic, I.; Kelnar, Ivan; Mendichi, R.; Tracz, A.; Filip, J.; Bertók, T.; Kasák, P.

    2018-01-01

    Roč. 72, č. 3 (2018), s. 711-718 ISSN 0366-6352 Institutional support: RVO:61389013 Keywords : all-polysaccharide composites * elemental analysis * film properties study Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 1.258, year: 2016

  10. Modifications of Saccharomyces pastorianus cell wall polysaccharides with brewing process.

    Science.gov (United States)

    Bastos, Rita; Coelho, Elisabete; Coimbra, Manuel A

    2015-06-25

    The cell wall polysaccharides of brewers spent yeast Saccharomyces pastorianus (BSY) and the inoculum yeast (IY) were studied in order to understand the changes induced by the brewing process. The hot water and alkali extractions performed solubilized mainly mannoproteins, more branched for BSY than those of IY. Also, (31)P solid state NMR showed that the BSY mannoproteins were 3 times more phosphorylated. By electron microscopy it was observed that the final residues of alkali sequential extraction until 4M KOH preserved the yeast three-dimensional structure. The final residues, composed mainly by glucans (92%), showed that the BSY, when compared with IY, contained higher amount of (1→4)-linked Glc (43% for BSY and 16% for IY) and lower (1→3)-linked Glc (17% for BSY and 42% for IY). The enzymatic treatment of final residue showed that both BSY and IY had (α1→4)-linked Glc and (β1→4)-linked Glc, in a 2:1 ratio, showing that S. pastorianus increases their cellulose-like linkages with the brewing process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Effect of growth conditions on production of rhamnose-containing cell wall and capsular polysaccharides by strains of Lactobacillus casei subsp. rhamnosus.

    Science.gov (United States)

    Wicken, A J; Ayres, A; Campbell, L K; Knox, K W

    1983-01-01

    Strains of Lactobacillus casei subsp. rhamnosus possessing two cell wall polysaccharides, a hexosamine-containing H-polysaccharide and a rhamnose-containing R-polysaccharide, were examined for the effect of growth conditions on the production of these two components. In strain NCTC 6375, R- and H-polysaccharides accounted for an estimated 44 and 20%, respectively, of the cell wall for organisms grown in batch culture with glucose as the carbohydrate source. Growth on fructose-containing media reduced the amount of R-polysaccharide by approximately 50% without affecting the amount of H-polysaccharide. Subculture of fructose-grown organisms in glucose restored the original proportions of the two polysaccharides. Galactose- and sucrose-grown cells behaved similarly to glucose-grown cells with respect to polysaccharide production, whereas growth in rhamnose or ribose showed values close to those for fructose-grown cells. Continuous culture of strain NCTC 6375 for more than 100 generations showed a gradual and irreversible reduction of the R-polysaccharide to less than 5% of the cell wall and an increase of the H-polysaccharide to 40% of the cell wall. Other type culture strains of L. casei subsp. rhamnosus, NCIB 7473 and ATCC 7469, behaved similarly in batch and continuous culture. In contrast, strains of L. casei subsp. rhamnosus isolated at the Institute of Dental Research showed phenotypic stability with respect to the relative proportions of R- and H-polysaccharides in both batch and continuous culture. Changes in polysaccharide composition of type culture strains were also mirrored in changes in the immunogenicity of the two components and resistance to the rate of enzymic lysis of whole organisms. For L. casei subsp. rhamnosus strain NCTC 10302 the R-polysaccharide is present entirely as capsular material. The amount of R-polysaccharide produced was also markedly dependent on the carbohydrate component of the medium in batch culture and both dilution rate and

  12. Brown algae overproduce cell wall polysaccharides as a protection mechanism against the heavy metal toxicity

    International Nuclear Information System (INIS)

    Andrade, Leonardo R.; Leal, Raquel N.; Noseda, Miguel; Duarte, Maria Eugenia R.; Pereira, Mariana S.; Mourao, Paulo A.S.; Farina, Marcos; Amado Filho, Gilberto M.

    2010-01-01

    Brown algae are often used as heavy metal biomonitors and biosorbents because they can accumulate high concentrations of metals. Cation-exchange performed by cell wall polysaccharides is pointed out as the main chemical mechanism for the metal sequestration. Here, we biochemically investigated if the brown alga Padina gymnospora living in a heavy metal contaminated area would modify their polysaccharidic content. We exposed non-living biomass to Cd and Pb and studied the metals adsorption and localization. We found that raw dried polysaccharides, sulfate groups, uronic acids, fucose, mannose, and galactose were significantly higher in contaminated algae compared with the control ones. Metal concentrations adsorbed by non-living biomass were rising comparatively to the tested concentrations. Electron microscopy showed numerous granules in the cell walls and X-ray microanalysis revealed Cd as the main element. We concluded that P. gymnospora overproduces cell wall polysaccharides when exposed to high metal concentrations as a defense mechanism.

  13. Ion chromatography characterization of polysaccharides in ancient wall paintings.

    Science.gov (United States)

    Colombin, Maria Perla; Ceccarini, Alessio; Carmignani, Alessia

    2002-08-30

    An analytical procedure for the characterisation of polysaccharides and the identification of plant gums in old polychrome samples is described. The procedure is based on hydrolysis with 2 M trifluoroacetic acid assisted by microwaves (20 min, 120 degrees C, 500 W), clean-up of the hydrolysate by an ion-exchange resin, and analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Using this method the hydrolysis time was reduced to 20 min and the chromatographic separation of seven monosaccharides (fucose, rhamnose, arabinose, galactose, glucose, mannose, xylose) and two uronic acids (galacturonic and glucuronic) was achieved in 40 min. The whole analytical procedure allows sugar determination in plant gums at picomole levels, with an average recovery of 72% with an RSD of 8% as tested on arabic gum. The analytical procedure was tested with several raw gums, watercolour samples and reference painting specimens prepared according to old recipes at the Opificio delle Pietre Dure of Florence (Italian Ministry of Cultural Heritage, Italy). All the data collected expressed in relative sugar percentage contents were submitted to principal components analysis for gum identification: five groups were spatially separated and this enabled the identification of arabic, tragacanth, karaya, cherry+ghatty, and guar+locust bean gum. Wall painting samples from Macedonian tombs (Greece) of the 4th-3rd Centuries B.C., processed by the suggested method, showed the presence of a complex paint media mainly consisting of tragacanth and fruit tree gums. Moreover, starch had probably been added to plaster as highlighted by the presence of a huge amount of glucose.

  14. Mass spectrometry for characterizing plant cell wall polysaccharides

    Directory of Open Access Journals (Sweden)

    Stefan eBauer

    2012-03-01

    Full Text Available Mass spectrometry is a selective and powerful technique to obtain identification and structural information on compounds present in complex mixtures. Since it requires only small sample amount it is an excellent tool for researchers interested in detecting changes in composition of complex carbohydrates of plants. This mini-review gives an overview of common mass spectrometry techniques applied to the analysis of plant cell wall carbohydrates. It presents examples in which mass spectrometry has been used to elucidate the structure of oligosaccharides derived from hemicelluloses and pectins and illustrates how information on sequence, linkages, branching and modifications are obtained from characteristic fragmentation patterns.

  15. Biosynthesis of the fungal cell wall polysaccharide galactomannan requires intraluminal GDP-mannose.

    Science.gov (United States)

    Engel, Jakob; Schmalhorst, Philipp S; Routier, Françoise H

    2012-12-28

    Fungal cell walls frequently contain a polymer of mannose and galactose called galactomannan. In the pathogenic filamentous fungus Aspergillus fumigatus, this polysaccharide is made of a linear mannan backbone with side chains of galactofuran and is anchored to the plasma membrane via a glycosylphosphatidylinositol or is covalently linked to the cell wall. To date, the biosynthesis and significance of this polysaccharide are unknown. The present data demonstrate that deletion of the Golgi UDP-galactofuranose transporter GlfB or the GDP-mannose transporter GmtA leads to the absence of galactofuran or galactomannan, respectively. This indicates that the biosynthesis of galactomannan probably occurs in the lumen of the Golgi apparatus and thus contrasts with the biosynthesis of other fungal cell wall polysaccharides studied to date that takes place at the plasma membrane. Transglycosylation of galactomannan from the membrane to the cell wall is hypothesized because both the cell wall-bound and membrane-bound polysaccharide forms are affected in the generated mutants. Considering the severe growth defect of the A. fumigatus GmtA-deficient mutant, proving this paradigm might provide new targets for antifungal therapy.

  16. 2-Fluoro-L-Fucose Is a Metabolically Incorporated Inhibitor of Plant Cell Wall Polysaccharide Fucosylation.

    Directory of Open Access Journals (Sweden)

    Jose A Villalobos

    Full Text Available The monosaccharide L-fucose (L-Fuc is a common component of plant cell wall polysaccharides and other plant glycans, including the hemicellulose xyloglucan, pectic rhamnogalacturonan-I (RG-I and rhamnogalacturonan-II (RG-II, arabinogalactan proteins, and N-linked glycans. Mutations compromising the biosynthesis of many plant cell wall polysaccharides are lethal, and as a result, small molecule inhibitors of plant cell wall polysaccharide biosynthesis have been developed because these molecules can be applied at defined concentrations and developmental stages. In this study, we characterize novel small molecule inhibitors of plant fucosylation. 2-fluoro-L-fucose (2F-Fuc analogs caused severe growth phenotypes when applied to Arabidopsis seedlings, including reduced root growth and altered root morphology. These phenotypic defects were dependent upon the L-Fuc salvage pathway enzyme L-Fucose Kinase/ GDP-L-Fucose Pyrophosphorylase (FKGP, suggesting that 2F-Fuc is metabolically converted to the sugar nucleotide GDP-2F-Fuc, which serves as the active inhibitory molecule. The L-Fuc content of cell wall matrix polysaccharides was reduced in plants treated with 2F-Fuc, suggesting that this molecule inhibits the incorporation of L-Fuc into these polysaccharides. Additionally, phenotypic defects induced by 2F-Fuc treatment could be partially relieved by the exogenous application of boric acid, suggesting that 2F-Fuc inhibits RG-II biosynthesis. Overall, the results presented here suggest that 2F-Fuc is a metabolically incorporated inhibitor of plant cellular fucosylation events, and potentially suggest that other 2-fluorinated monosaccharides could serve as useful chemical probes for the inhibition of cell wall polysaccharide biosynthesis.

  17. 2-Fluoro-L-Fucose Is a Metabolically Incorporated Inhibitor of Plant Cell Wall Polysaccharide Fucosylation

    Science.gov (United States)

    Wallace, Ian S.

    2015-01-01

    The monosaccharide L-fucose (L-Fuc) is a common component of plant cell wall polysaccharides and other plant glycans, including the hemicellulose xyloglucan, pectic rhamnogalacturonan-I (RG-I) and rhamnogalacturonan-II (RG-II), arabinogalactan proteins, and N-linked glycans. Mutations compromising the biosynthesis of many plant cell wall polysaccharides are lethal, and as a result, small molecule inhibitors of plant cell wall polysaccharide biosynthesis have been developed because these molecules can be applied at defined concentrations and developmental stages. In this study, we characterize novel small molecule inhibitors of plant fucosylation. 2-fluoro-L-fucose (2F-Fuc) analogs caused severe growth phenotypes when applied to Arabidopsis seedlings, including reduced root growth and altered root morphology. These phenotypic defects were dependent upon the L-Fuc salvage pathway enzyme L-Fucose Kinase/ GDP-L-Fucose Pyrophosphorylase (FKGP), suggesting that 2F-Fuc is metabolically converted to the sugar nucleotide GDP-2F-Fuc, which serves as the active inhibitory molecule. The L-Fuc content of cell wall matrix polysaccharides was reduced in plants treated with 2F-Fuc, suggesting that this molecule inhibits the incorporation of L-Fuc into these polysaccharides. Additionally, phenotypic defects induced by 2F-Fuc treatment could be partially relieved by the exogenous application of boric acid, suggesting that 2F-Fuc inhibits RG-II biosynthesis. Overall, the results presented here suggest that 2F-Fuc is a metabolically incorporated inhibitor of plant cellular fucosylation events, and potentially suggest that other 2-fluorinated monosaccharides could serve as useful chemical probes for the inhibition of cell wall polysaccharide biosynthesis. PMID:26414071

  18. Combining polysaccharide biosynthesis and transport in a single enzyme: dual-function cell wall glycan synthases.

    Directory of Open Access Journals (Sweden)

    Jonathan Kent Davis

    2012-06-01

    Full Text Available Extracellular polysaccharides are synthesized by a wide variety of species, from unicellular bacteria and Archaea to the largest multicellular plants and animals in the biosphere. In every case, the biosynthesis of these polymers requires transport across a membrane, from the cytosol to either the lumen of secretory pathway organelles or directly into the extracellular space. Although some polysaccharide biosynthetic substrates are moved across the membrane to sites of polysaccharide synthesis by separate transporter proteins before being incorporated into polymers by glycosyltransferase proteins, many polysaccharide biosynthetic enzymes appear to have both transporter and transferase activities. In these cases, the biosynthetic enzymes utilize substrate on one side of the membrane and deposit the polymer product on the other side. This review discusses structural characteristics of plant cell wall glycan synthases that couple synthesis with transport, drawing on what is known about such dual-function enzymes in other species.

  19. Ionizing radiation damage in Micrococcus radiodurans cell wall: release of polysaccharide

    International Nuclear Information System (INIS)

    Mitchel, R.E.J.

    1976-01-01

    Sublethal 60 Co γ-irradiation of the bacterium Micrococcus radiodurans in aqueous suspension results in a loss of up to 6 percent of its cellular dry weight and 30 percent of its wet weight. In the process some specific cell wall polysaccharides, including a polymer of glucose and N-acylated glucosamine, are released into the surrounding medium. These polysaccharides appear to originate from a hydrophobic site in the middle, lipid-rich, cell wall layer. The damage to this layer which results in the release of these and other polymers may be due to a disruption of this hydrophobic site. The polysaccharide containing glucose and N-acylated glucosamine exists as a high molecular weight polymer in unirradiated cells, but irradiation causes some degradation prior to release. In a free state this polysaccharide is considerably less sensitive to radiolytic degradation than in a bound state. Free radicals generated from surrounding water by ionizing radiation initiate the release, hydroxyl radicals being the most important species. Oxygen protects the cell wall against loss of the polysaccharides, apparently by a mechanism which does not depend on the ability of O 2 to scavenge hydrogen atoms and aqueous electrons

  20. Combined Enzymatic and High-Pressure Processing Affect Cell Wall Polysaccharides in Berries

    NARCIS (Netherlands)

    Hilz, H.; Lille, M.; Poutanen, K.; Schols, H.A.; Voragen, A.G.J.

    2006-01-01

    The effect of high-pressure processing (HPP) on cell wall polysaccharides in berries was investigated. HPP decreased the degree of methyl esterification (DM), probably by activation of pectin methyl esterase (PME), and improved the extractability of pectins. When commercial enzyme mixtures were

  1. Transgenic modification of potato pectic polysaccharides also affects type and level of cell wall xyloglucan

    NARCIS (Netherlands)

    Huang, Jie Hong; Jiang, Rui; Kortstee, Anne; Dees, Dianka C.T.; Trindade, Luisa M.; Gruppen, Harry; Schols, Henk A.

    2017-01-01

    BACKGROUND: Genes encoding pectic enzymes were introduced into wild-type potato Karnico. Cell wall materials were extracted from Karnico and transgenic lines expressing β-galactosidase (β-Gal-14) or rhamnogalacturonan lyase (RGL-18). Pectic polysaccharides from the β-Gal-14 transgenic line exhibited

  2. Turnover of galactans and other cell wall polysaccharides during development of flax plants

    International Nuclear Information System (INIS)

    Gorshkova, T.A.; Chemikosova, S.B.; Lozovaya, V.V.; Carpita, N.C.

    1997-01-01

    We investigated the synthesis and turnover of cell wall polysaccharides of the flax (Linum usitatissimum L.) plant during development of the phloem fibers. One-month-old flax plants were exposed to a 40-min pulse with 14CO2 followed by 8-h, 24-h, and 1-month periods of chase with ambient CO2, and radioactivity in cell wall sugars was determined in various plant parts. The relative radioactivity of glucose in noncellulosic polysaccharides was the highest compared with all other cell wall sugars immediately after the pulse and decreased substantially during the subsequent chase. The relative radioactivities of the other cell wall sugars changed with differing rates, indicating turnover of specific polysaccharides. Notably, after 1 month of chase there was a marked decrease in the proportional mass and total radioactivity in cell wall galactose, indicating a long-term turnover of the galactans enriched in the fiber-containing tissues. The ratio of radiolabeled xylose to arabinose also increased during the chase, indicating a turnover of arabinose-containing polymers and interconversion to xylose. The pattern of label redistribution differed between organs, indicating that the cell wall turnover processes are tissue- and cell-specific

  3. Characterisation of cell-wall polysaccharides from mandarin segment membranes

    NARCIS (Netherlands)

    Coll-Almela, L.; Saura-Lopez, D.; Laencina-Sanchez, J.; Schols, H.A.; Voragen, A.G.J.; Ros-García, J.M.

    2015-01-01

    In an attempt to develop a process of enzymatic peeling of mandarin segments suitable for use on an industrial scale, the cell wall fraction of the segment membrane of Satsuma mandarin fruits was extracted to obtain a chelating agent-soluble pectin fraction (ChSS), a dilute sodium hydroxide-soluble

  4. Structures of two cell wall-associated polysaccharides of a Streptococcus mitis biovar 1 strain. A unique teichoic acid-like polysaccharide and the group O antigen which is a C-polysaccharide in common with pneumococci

    DEFF Research Database (Denmark)

    Bergström, N; Jansson, P.-E.; Kilian, Mogens

    2000-01-01

    The cell wall of Streptococcus mitis biovar 1 strain SK137 contains the C-polysaccharide known as the common antigen of a closely related species Streptococcus pneumoniae, and a teichoic acid-like polysaccharide with a unique structure. The two polysaccharides are different entities and could...... be partially separated by gel chromatography. The structures of the two polysaccharides were determined by chemical methods and by NMR spectroscopy. The teichoic acid-like polymer has a heptasaccharide phosphate repeating unit with the following structure: The structure neither contains ribitol nor glycerol...... phosphate as classical teichoic acids do, thus we have used the expression teichoic acid-like for this polysaccharide. The following structure of the C-polysaccharide repeating unit was established: where AAT is 2-acetamido-4-amino-2,4, 6-trideoxy-D-galactose. It has a carbohydrate backbone identical...

  5. Effect of Agave tequilana juice on cell wall polysaccharides of three Saccharomyces cerevisiae strains from different origins.

    Science.gov (United States)

    Aguilar-Uscanga, Blanca; Arrizon, Javier; Ramirez, Jesús; Solis-Pacheco, Josué

    2007-02-01

    In this study, a characterization of cell wall polysaccharide composition of three yeasts involved in the production of agave distilled beverages was performed. The three yeast strains were isolated from different media (tequila, mezcal and bakery) and were evaluated for the beta(1,3)-glucanase lytic activity and the beta-glucan/ mannan ratio during the fermentation of Agave tequilana juice and in YPD media (control). Fermentations were performed in shake flasks with 30 g l(-1) sugar concentration of A. tequilana juice and with the control YPD using 30 g l(-1) of glucose. The three yeasts strains showed different levels of beta-glucan and mannan when they were grown in A. tequilana juice in comparison to the YPD media. The maximum rate of cell wall lyses was 50% lower in fermentations with A. tequilana juice for yeasts isolated from tequila and mezcal than compared to the bakery yeast.

  6. Enzymes in biogenesis of plant cell wall polysaccharides. Enzyme characterization using tracer techniques

    International Nuclear Information System (INIS)

    Dickinson, D.B.

    1975-01-01

    Enzymes and metabolic pathways, by which starch and cell wall polysaccharides are formed, were investigated in order to learn how these processes are regulated and to identify the enzymatic regulatory mechanisms involved. Germinating lily pollen was used for studies of cell wall formation, and pollen and maize endosperm for studies of starch biosynthesis. Hexokinase being the first step in conversion of hexoses to starch, wall polysaccharides and respiratory substrates, maize endosperm enzyme was assayed by its conversion of 14 C-hexose to 14 C-hexose-6-P, and rapid separation of the two labelled compounds on anion-exchange paper. This enzyme did not appear to be under tight regulation by feed-back inhibition or activation, nor to be severely inhibited by glucose-6-P or activated by citrate. ADP-glucose pyrophosphorylase and other pyrophosphorylases were assayed radiochemically with 14 C-glucose-1-P (forward direction) or 32-PPsub(i) (reverse direction). They showed that the maize endosperm enzyme was activated by the glycolytic intermediates fructose-6-P and 3-phosphoglycerate, and that low levels of the enzyme were present in the high sucrose-low starch mutant named shrunken-2. Under optimal in-vitro assay conditions, the pollen enzyme reacted four times faster than the observed in-vivo rate of starch accumulation. Biogenesis of plant cell wall polysaccharides requires the conversion of hexose phosphates to various sugar nucleotides and utilization of the latter by the appropriate polysaccharide synthetases. Lily pollen possesses a β-1,3-glucan synthetase which is activated up to six-fold by β-linked oligosaccharides. Hence, the in-vivo activity of this enzyme may be modulated by such effector molecules

  7. Soft X-ray induced chemical modification of polysaccharides in vascular plant cell walls

    International Nuclear Information System (INIS)

    Cody, George D.; Brandes, Jay; Jacobsen, Chris; Wirick, Susan

    2009-01-01

    Scanning transmission X-ray microscopy and micro carbon X-ray Absorption Near Edge Spectroscopy (C-XANES) can provide quantitative information regarding the distribution of the biopolymers cellulose, hemicellulose, and lignin in vascular plant cell walls. In the case of angiosperms, flowering plants, C-XANES may also be able to distinguish variations in lignin monomer distributions throughout the cell wall. Polysaccharides are susceptible to soft X-ray irradiation induced chemical transformations that may complicate spectral analysis. The stability of a model polysaccharide, cellulose acetate, to variable doses of soft X-rays under conditions optimized for high quality C-XANES spectroscopy was investigated. The primary chemical effect of soft X-ray irradiation on cellulose acetate involves mass loss coincident with de-acetylation. A lesser amount of vinyl ketone formation also occurs. Reduction in irradiation dose via defocusing does enable high quality pristine spectra to be obtained. Radiation induced chemical modification studies of oak cell wall reveals that cellulose and hemicellulose are less labile to chemical modification than cellulose acetate. Strategies for obtaining pristine C-XANES spectra of polysaccharides are presented.

  8. Understanding the relationship between cotton fiber properties and non-cellulosic cell wall polysaccharides

    DEFF Research Database (Denmark)

    Rajasundaram, Dhivyaa; Runavot, Jean-Luc; Guo, Xiaoyuan

    2014-01-01

    cotton fibers, which are of both biological and industrial importance. To this end, we attempted to study cotton fiber characteristics together with glycan arrays using regression based approaches. Taking advantage of the comprehensive microarray polymer profiling technique (CoMPP), 32 cotton lines from...... different cotton species were studied. The glycan array was generated by sequential extraction of cell wall polysaccharides from mature cotton fibers and screening samples against eleven extensively characterized cell wall probes. Also, phenotypic characteristics of cotton fibers such as length, strength...

  9. Identification of polysaccharide hydrolases involved in autolytic degradation of Zea cell walls

    International Nuclear Information System (INIS)

    Nock, L.P.; Smith, C.J.

    1987-01-01

    Cell walls of Zea mays (cv L.G.11) seedlings labeled with 14 C were treated with α-amylase from Bacillus subtilis to remove starch and mixed linkage glucans. These walls released arabinose, xylose, galactose, and galacturonic acid in addition to glucose when they were allowed to autolyze. Methylation analysis was performed on samples of wall which had been incubated autolytically and the results indicated that degradation of the major polymer of the wall, the glucoarabinoxylan, had occurred. A number of glycanases could be dissociated from the wall by use of 3 M LiCL. The proteins which were released were found to contain a number of exoglycosidase activities in addition to being effective in degrading the polysaccharide substrates, araban, xylan, galactan, laminarin, mannan, and polygalacturonic acid. The effects of these enzymes on the wall during autolysis appear to result from endo-activity in addition to exo-activity. The structural changes that occurred in the cell walls during autolysis were found to be related to the changes previously found to occur in cell walls during auxin induced extension

  10. Effects of exogenous salicylic acid on cell wall polysaccharides and aluminum tolerance of trichosanthes kirilowii

    International Nuclear Information System (INIS)

    Xu, G.; Liu, D.; Xio, Y.; Liu, P.; Gao, P. P.; Cao, L.; Wu, Y.

    2015-01-01

    A hydroponic experiment was conducted to study the effects of exogenous salicylic acid (SA) on root length, relative aluminum content in the apical cell wall, acid phosphatase (APA) and pectin methyl esterase (PME) activity, root pectin, hemicellulose 1(HC1), and hemicellulose 2 (HC2) contents of Anguo Trichosanthes kirilowii (Al-tolerant genotype) and Pujiang T. kirilowii (Al-sensitive genotype) under 800 micro mol/L of aluminum stress. The results showed that the growth of Al-tolerant Anguo T. kirilowii and Al-sensitive Pujiang T. kirilowii was inhibited when exposed to 800 micro mol/L of aluminum solution. APA and PME activities were also enhanced for both genotypes. The contents of relative aluminum, pectin, HC1, and HC2, as well as Al accumulation in the root tips were increased under aluminum toxicity. Pujiang T. kirilowii showed higher enzyme activity and cell wall polysaccharide contents than Anguo T. kirilowii. In addition, the root cell wall pectin, HC1, and HC2 contents of Pujiang T. kirilowii were increased by a large margin, showing its greater sensitivity to aluminum toxicity. Root length is an important indicator of aluminum toxicity, and has an important relationship with cell wall polysaccharide content. Aluminum toxicity led to the accumulation of pectin and high PME activity, and also increased the number of free carboxyl groups, which have more aluminum binding sites. Membrane skim increased extensively with the increase in APA activity, damaging membrane structure and function. Different SA concentrations can decrease enzyme activity and cell wall polysaccharide content to some extent. With the addition of different SA concentrations, the root relative aluminum content, cell wall polysaccharide content, APA and PME activities decreased. Aluminum toxicity to both genotypes of T. kirilowii was relieved in different degrees as exogenous SA concentration increased. Inter-simple sequence repeat (ISSR) marker was used to examine the genetic distance

  11. Xylose-rich polysaccharides from the primary walls of embryogenic cell line of Pinus caribaea.

    Science.gov (United States)

    Mollard, A; Domon, J M; David, H; Joseleau, J P

    1997-08-01

    Embryogenic cell lines of Pinus caribaea were isolated from somatic embryogenesis from zygotic embryos. Previous studies showed that the proteins and glycoproteins were characteristic of the embryogenic state. In the present work we were seeking typical feature in the polysaccharide from the cell walls of embryogenic calli at nine days of culture. Sequential extraction with water, ammonium oxalate, dimethyl sulfoxide, sodium borohydride and 4.3 M potassium hydroxide revealed that the extracted polysaccharides contained high proportions of arabinose and significant amounts of xylose. Fractionation of the hydrosoluble polymers on DEAE cellulose afforded a xylose-rich fraction (80% xylose, 24% glucose and lower properties of fucose and mannose). Methylation analysis and 13C-NMR spectra showed that the glycan backbone consisted of beta 1 --> 4 linked xylosyl residues Similar study of the fractions extracted respectively with DMSO and 4.3 M KOH showed the presence of polydisperse glycoxylans but excluded the presence of xyloglucan in significant amount. This could be a characteristic feature of embryogenic cells walls of Pinus caribaea or could be typical of cells grown as calluses. In the various fractions obtained from DEAE cellulose chromatography of the alkaline extract the infrequent occurrence of fucoxylans beside an arabinogalactan showed again the unusual nature of the cell wall polymers of this embryogenic lines, which seems to differ greatly from those found in the primary wall of cells from suspension cultures.

  12. [Monosaccharide composition analysis and its content determination of polysaccharides from Rhaponticum uniforum].

    Science.gov (United States)

    Li, Fa-Sheng; Xu, Heng-Gui; Yan, Xiao-Mei; Li, Ming-Yang; Liu, Hui

    2008-06-01

    To analyze the monosaccharide composition in the polysaccharides from Rhaponticum uniforum, determine the content of monosaccharide, and provide some references for further research. The monosaccharide composition was determined by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Phenol-sulfuric acid method was used for the determination of the content of polysaccharide. The monosaccharides composition in polysaccharides from R. uniforum are glucose, arabonose and fructose. Their molar ratios are 1 : 1.61 : 2.21. The content of polysaccharide is 95.78%, taking the mixture of monosaccharide compositions as reference substances. HPAEC-PAD can be used to analyze the monosaccharide composition in the polysaccharide with high precision, and the method of phenol-sulfuric acid is simple, convenient and reliable.

  13. Dissecting the polysaccharide-rich grape cell wall matrix using recombinant pectinases during winemaking

    DEFF Research Database (Denmark)

    Gao, Yu; Fangel, Jonatan Ulrik; Willats, William George Tycho

    2016-01-01

    different combinations of purified recombinant pectinases with cell wall profiling tools to follow the deconstruction process during winemaking. Multivariate data analysis of the glycan microarray (CoMPP) and gas chromatography (GC) results revealed that pectin lyase performed almost as effectively in de......The effectiveness of enzyme-mediated-maceration in red winemaking relies on the use of an optimum combination of specific enzymes. A lack of information on the relevant enzyme activities and the corresponding polysaccharide-rich berry cell wall structure is a major limitation. This study used......-pectination as certain commercial enzyme mixtures. Surprisingly the combination of endo-polygalacturonase and pectin-methyl-esterase only unraveled the cell walls without de-pectination. Datasets from the various combinations used confirmed pectin-rich and xyloglucan-rich layers within the grape pomace. These data...

  14. Cell wall polysaccharides hydrolysis of malting barley (Hordeum vulgare L.: a review

    Directory of Open Access Journals (Sweden)

    Jamar, C.

    2011-01-01

    Full Text Available Malting quality results from the different steps of the malting process. Malting uses internal changes of the seed occurring during germination, such as enzymes synthesis, to obtain a good hydrolysis process and the components required. Among the three main hydrolytic events observed, that are namely starch degradation, cell wall breakdown and protein hydrolysis, an efficient cell wall polysaccharides hydrolysis is an essential condition for a final product of quality. Indeed, because of the physical barrier of the cell wall, cell wall polysaccharides hydrolysis is one of the first steps expected from the process to gain access to the cell components. Moreover, viscosity problem and haze formation in malting industry are related to their presence during the process when inefficient degradation occurs, leading to increased production time and cost. Understanding the key elements in cell wall degradation is important for a better control. (1-3,1-4-β-glucans and arabinoxylans are the main constituents of cell wall. (1-3,1-4-β-glucans are unbranched chains of β-D-glucopyranose residues with β-(1,3 linkages and β-(1,4 linkages. Arabinoxylan consists in a backbone of D-xylanopyranosyl units linked by β-(1-4 bonds connected to single L-arabinofuranose by α-(1→2 or α-(1→3-linkages. Degradation of (1-3,1-4-β-glucans is processed by the (1-3,1-4-β-glucanases, the β-glucosidases and the β-glucane exohydrolases. It seems that the (1-3-β-glucanases are also involved. Arabinoxylans are mainly decomposed by (1-4-β-xylan endohydrolase, arabinofuranosidase and β-xylosidase.

  15. Effects of Gamma irradiation on uronic acid sugars as cell wall polysaccharide model systems

    International Nuclear Information System (INIS)

    Irawati, Zubaidah; Pilnik, W.

    2001-01-01

    Irradiation is an alternative preservation method with can be utilized to extend the self-life of agricultural products by eliminating number of insects, and decreasing microbial growth effectively. Cell wall polysaccharides which mainly consist of pectic substances, hemicelluloses and cellulose play a major role on the immediate fruits. their degradation mechanism can be elucidates by studying their degradation products resulting from the irradiated cell wall or cell wall components. Isolated apple pectin and alginates as different in solid state by gamma irradiation at 15-30 kGy under two different humidities. The parameters observed were viscosity, β-elimination in the ester groups of pectin, and distribution of molecular weight. Irradiation with the doses of 15-30 kGy could reduce the viscosity of pectin and alginates, while irradiation did not cause β-elimination in the ester groups of pectin as confirmed by titration and ion exchange chromatography methods. The formation of 4,5-unsaturated uronosyl residues as a product of cleavage of the pectin backbone via- β-elimination was not found in irradiated pectin as confirmed by thio barbiture acid (TBA) test. High Performance Size Exclusion Chromatography (HPSEC) analysis for the irradiated polysaccharide model systems revealed that the average number of molecular weight showed a decrease by increasing radiation dose. Storage condition in two different relative humidities affected significantly the degree of polymerization of pectin and alginates in solid state

  16. Temperature modulates the cell wall mechanical properties of rice coleoptiles by altering the molecular mass of hemicellulosic polysaccharides

    Science.gov (United States)

    Nakamura, Yukiko; Wakabayashi, Kazuyuki; Hoson, Takayuki

    2003-01-01

    The present study was conducted to investigate the mechanism inducing the difference in the cell wall extensibility of rice (Oryza sativa L. cv. Koshihikari) coleoptiles grown under various temperature (10-50 degrees C) conditions. The growth rate and the cell wall extensibility of rice coleoptiles exhibited the maximum value at 30-40 degrees C, and became smaller as the growth temperature rose or dropped from this temperature range. The amounts of cell wall polysaccharides per unit length of coleoptile increased in coleoptiles grown at 40 degrees C, but not at other temperature conditions. On the other hand, the molecular size of hemicellulosic polysaccharides was small at temperatures where the cell wall extensibility was high (30-40 degrees C). The autolytic activities of cell walls obtained from coleoptiles grown at 30 and 40 degrees C were substantially higher than those grown at 10, 20 and 50 degrees C. Furthermore, the activities of (1-->3),(1-->4)-beta-glucanases extracted from coleoptile cell walls showed a similar tendency. When oat (1-->3),(1-->4)-beta-glucans with high molecular mass were incubated with the cell wall enzyme preparations from coleoptiles grown at various temperature conditions, the extensive molecular mass downshifts were brought about only by the cell wall enzymes obtained from coleoptiles grown at 30-40 degrees C. There were close correlations between the cell wall extensibility and the molecular mass of hemicellulosic polysaccharides or the activity of beta -glucanases. These results suggest that the environmental temperature regulates the cell wall extensibility of rice coleoptiles by modifying mainly the molecular mass of hemicellulosic polysaccharides. Modulation of the activity of beta-glucanases under various temperature conditions may be involved in the alteration of the molecular size of hemicellulosic polysaccharides.

  17. Fast data preprocessing for chromatographic fingerprints of tomato cell wall polysaccharides using chemometric methods.

    Science.gov (United States)

    Quéméner, Bernard; Bertrand, Dominique; Marty, Isabelle; Causse, Mathilde; Lahaye, Marc

    2007-02-02

    The variability in the chemistry of cell wall polysaccharides in pericarp tissue of red-ripe tomato fruit (Solanum lycopersicon Mill.) was characterized by chemical methods and enzymatic degradations coupled to high performance anion exchange chromatography (HPAEC) and mass spectrometry analysis. Large fruited line, Levovil (LEV) carrying introgressed chromosome fragments from a cherry tomato line Cervil (CER) on chromosomes 4 (LC4), 9 (LC9), or on chromosomes 1, 2, 4 and 9 (LCX) and containing quantitative trait loci (QTLs) for texture traits, was studied. In order to differentiate cell wall polysaccharide modifications in the tomato fruit collection by multivariate analysis, chromatograms were corrected for baseline drift and shift of the component elution time using an approach derived from image analysis and mathematical morphology. The baseline was first corrected by using a "moving window" approach while the peak-matching method developed was based upon location of peaks as local maxima within a window of a definite size. The fast chromatographic data preprocessing proposed was a prerequisite for the different chemometric treatments, such as variance and principal component analysis applied herein to the analysis. Applied to the tomato collection, the combined enzymatic degradations and HPAEC analyses revealed that the firm LCX and CER genotypes showed a higher proportion of glucuronoxylans and pectic arabinan side chains while the mealy LC9 genotype demonstrated the highest content of pectic galactan side chains. QTLs on tomato chromosomes 1, 2, 4 and 9 contain important genes controlling glucuronoxylan and pectic neutral side chains biosynthesis and/or metabolism.

  18. Dissecting the polysaccharide-rich grape cell wall matrix using recombinant pectinases during winemaking.

    Science.gov (United States)

    Gao, Yu; Fangel, Jonatan U; Willats, William G T; Vivier, Melané A; Moore, John P

    2016-11-05

    The effectiveness of enzyme-mediated-maceration in red winemaking relies on the use of an optimum combination of specific enzymes. A lack of information on the relevant enzyme activities and the corresponding polysaccharide-rich berry cell wall structure is a major limitation. This study used different combinations of purified recombinant pectinases with cell wall profiling tools to follow the deconstruction process during winemaking. Multivariate data analysis of the glycan microarray (CoMPP) and gas chromatography (GC) results revealed that pectin lyase performed almost as effectively in de-pectination as certain commercial enzyme mixtures. Surprisingly the combination of endo-polygalacturonase and pectin-methyl-esterase only unraveled the cell walls without de-pectination. Datasets from the various combinations used confirmed pectin-rich and xyloglucan-rich layers within the grape pomace. These data support a proposed grape cell wall model which can serve as a foundation to evaluate testable hypotheses in future studies aimed at developing tailor-made enzymes for winemaking scenarios. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Modification of Cell Wall Polysaccharides during Drying Process Affects Texture Properties of Apple Chips

    Directory of Open Access Journals (Sweden)

    Min Xiao

    2018-01-01

    Full Text Available The influences of hot air drying (AD, medium- and short-wave infrared drying (IR, instant controlled pressure drop drying (DIC, and vacuum freeze drying (FD on cell wall polysaccharide modification were studied, and the relationship between the modifications and texture properties was analyzed. The results showed that the DIC treated apple chips exhibited the highest crispness (92 and excellent honeycomb-like structure among all the dried samples, whereas the FD dried apple chips had low crispness (10, the minimum hardness (17.4 N, and the highest volume ratio (0.76 and rehydration ratio (7.55. Remarkable decreases in the contents of total galacturonic acid and the amounts of water extractable pectin (WEP were found in all the dried apple chips as compared with the fresh materials. The highest retention of WEP fraction (102.7 mg/g AIR was observed in the FD dried apple chips, which may lead to a low structural rigidity and may be partially responsible for the lower hardness of the FD apple chips. In addition, the crispness of the apple chips obtained by DIC treatment, as well as AD and IR at 90°C, was higher than that of the samples obtained from the other drying processes, which might be due to the severe degradation of pectic polysaccharides, considering the results of the amounts of pectic fractions, the molar mass distribution, and concentrations of the WEP fractions. Overall, the data suggested that the modifications of pectic polysaccharides of apple chips, including the amount of the pectic fractions and their structural characteristics and the extent of degradation, significantly affect the texture of apple chips.

  20. Polyphenolic, polysaccharide and oligosaccharide composition of Tempranillo red wines and their relationship with the perceived astringency.

    Science.gov (United States)

    Quijada-Morín, Natalia; Williams, Pascale; Rivas-Gonzalo, Julián C; Doco, Thierry; Escribano-Bailón, M Teresa

    2014-07-01

    The influence of the proanthocyanidic, polysaccharide and oligosaccharide composition on astringency perception of Tempranillo wines has been evaluated. Statistical analyses revealed the existence of relationships between chemical composition and perceived astringency. Proanthocyanidic subunit distribution had the strongest contribution to the multiple linear regression (MLR) model. Polysaccharide families showed clear opposition to astringency perception according to principal component analysis (PCA) results, being stronger for mannoproteins and rhamnogalacturonan-II (RG-II), but only Polysaccharides Rich in Arabinose and Galactose (PRAGs) were considered in the final fitted MLR model, which explained 96.8% of the variability observed in the data. Oligosaccharides did not show a clear opposition, revealing that structure and size of carbohydrates are important for astringency perception. Mannose and galactose residues in the oligosaccharide fraction are positively related to astringency perception, probably because its presence is consequence of the degradation of polysaccharides. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. [Purification and composition analysis of polysaccharide RCPS from Rhodiola crenulata].

    Science.gov (United States)

    Song, Xue-Wei; Ren, Lei; Han, Yong-Ping; Cui, Zhi-Bin; Huang, Jia-Kun

    2008-03-01

    Hot water extracting and ethanol precipitating method was employed to isolate polysaccharides. RCP (Rhodiola crenulata polysaccharide) was fractionally precipitated with EtOH. RCP3 (Rhodiola crenulata polysaccharide 3) was one of the three fractions. RCPS was obtained after RCP3 was purified by deproteination; decolourization and gel chromatography on Sephadex G-100. The homogeneity and molecular masses of RCPS were proved by HLGPC. The amount of total carbohydrates of RCPS was measured with phenol-sulfuric acid method. IR spectrometry and UV-spectrophotometer were used to determine the characteristic absorption of RCPS. The monosaccharides contained in the RCPS were analyzed by GC. The amount of total carbohydrates in RCPS is 99.11%. The molecular weight was 27 876. IR spectrometry analysis indicated that RCPS showed typical signals of acid polysaccharide, including signals at 3 424.83, 2 934.10, 1 742.11, 1 438.96, 1 261.40, 1 103.54 and 832.86 cm(-1); UV-spectrophotometer analysis indicated that RCPS showed a signal of polysaccharide at 195 nm and no signals of protein, nucleic acid at 260 and 280 nm. The monosaccharide constituents of RCPS were Rha, Ara, Xyl, Man, Glu, Gal and GalA, and their molar proportions were 1 : 2.96 : 0.21 : 0.26 : 0.08 : 0.58 and 0.15, respectively.

  2. Extractability and digestibility of plant cell wall polysaccharides during hydrothermal and enzymatic degradation of wheat straw (Triticum aestivum L.)

    DEFF Research Database (Denmark)

    Hansen, Mads A.T.; Ahl, Louise I.; Pedersen, Henriette L.

    2014-01-01

    to about 20, but mostly around 3-8, and notably more acetylated in stems. Arabinoxylan (AX) and mixed-linkage glucan (MLG) became water-extractable while xylan, xyloglucan (XG), mannan and glucan remained only alkali-extractable. All polysaccharides became partly digestible after pretreatment however......, regardless their extractability in water or only alkali. Based on the results, AX and MLG appear to be loosely bound in the cell wall matrix while the other polysaccharides are bound more tightly and shielded from enzymatic attack by AX and MLG until pretreatment. The gradual solubilisation and digestion...

  3. Anatomy and cell wall polysaccharides of almond (Prunus dulcis D. A. Webb) seeds.

    Science.gov (United States)

    Dourado, Fernando; Barros, António; Mota, Manuel; Coimbra, Manuel A; Gama, Francisco M

    2004-03-10

    The anatomy of Prunus dulcis was analyzed by applying several differential staining techniques and light microscopy. Prunus dulcis seed has a thin and structurally complex seed coat, with lignified cellulosic tissue. The embryo has two voluminous cotyledons. Cotyledon cells have a high number of protein and lipid bodies, some of which have phytin. The provascular tissue, located in the cotyledons, is oriented in small bundles perpendicular to the transverse embryonic axis. Prunus dulcis cell wall material is very rich in arabinose (45 mol %). Glucose (23%), uronic acids (12%), and xylose (12%) are also major sugar components. The polymers obtained from the imidazole and Na(2)CO(3) extracts contain mainly pectic substances rich in arabinose, but the sugar content of these extracts was very low. The majority of the pectic substances (also rich in arabinose) was recovered with the KOH extracts. These extracts, with high sugar content, yielded also xyloglucans and acidic xylans. The 4 M KOH + H(3)BO(3) extracts yielded polysaccharides rich in uronic acids and xylose and very rich in arabinose, accounting for 27% of the cell wall material.

  4. Molecular mapping of the cell wall polysaccharides of the human pathogen Streptococcus agalactiae

    Science.gov (United States)

    Beaussart, Audrey; Péchoux, Christine; Trieu-Cuot, Patrick; Hols, Pascal; Mistou, Michel-Yves; Dufrêne, Yves F.

    2014-11-01

    The surface of many bacterial pathogens is covered with polysaccharides that play important roles in mediating pathogen-host interactions. In Streptococcus agalactiae, the capsular polysaccharide (CPS) is recognized as a major virulence factor while the group B carbohydrate (GBC) is crucial for peptidoglycan biosynthesis and cell division. Despite the important roles of CPS and GBC, there is little information available on the molecular organization of these glycopolymers on the cell surface. Here, we use atomic force microscopy (AFM) and transmission electron microscopy (TEM) to analyze the nanoscale distribution of CPS and GBC in wild-type (WT) and mutant strains of S. agalactiae. TEM analyses reveal that in WT bacteria, peptidoglycan is covered with a very thin (few nm) layer of GBC (the ``pellicle'') overlaid by a 15-45 nm thick layer of CPS (the ``capsule''). AFM-based single-molecule mapping with specific antibody probes shows that CPS is exposed on WT cells, while it is hardly detected on mutant cells impaired in CPS production (ΔcpsE mutant). By contrast, both TEM and AFM show that CPS is over-expressed in mutant cells altered in GBC expression (ΔgbcO mutant), indicating that the production of the two surface glycopolymers is coordinated in WT cells. In addition, AFM topographic imaging and molecular mapping with specific lectin probes demonstrate that removal of CPS (ΔcpsE), but not of GBC (ΔgbcO), leads to the exposure of peptidoglycan, organized into 25 nm wide bands running parallel to the septum. These results indicate that CPS forms a homogeneous barrier protecting the underlying peptidoglycan from environmental exposure, while the presence of GBC does not prevent peptidoglycan detection. This work shows that single-molecule AFM, combined with high-resolution TEM, represents a powerful platform for analysing the molecular arrangement of the cell wall polymers of bacterial pathogens.

  5. Chemical Composition and Antioxidant Activities of Three Polysaccharide Fractions from Pine Cones

    Directory of Open Access Journals (Sweden)

    Pu Wang

    2012-11-01

    Full Text Available The traditional method of gas chromatography-mass spectrometry for monosaccharide component analysis with pretreatment of acetylation is described with slight modifications and verified in detail in this paper. It was then successfully applied to the quantitative analysis of component monosaccharides in polysaccharides extracted from the pine cones. The results demonstrated that the three pine cone polysaccharides all consisted of ribose, rhamnose, arabinose, xylose, mannose, glucose and galactose in different molar ratios. According to the recovery experiment, the described method was proved accurate and practical for the analysis of pine cone polysaccharides, meeting the need in the field of chemical analysis of Pinus plants. Furthermore; the chemical characteristics, such as neutral sugar, uronic acids, amino acids, molecular weights, and antioxidant activities of the polysaccharides were investigated by chemical and instrumental methods. The results showed that the chemical compositions of the polysaccharides differed from each other, especially in the content of neutral sugar and uronic acid. In the antioxidant assays, the polysaccharide fractions exhibited effective scavenging activities on ABTS radical and hydroxyl radical, with their antioxidant capabilities decreasing in the order of PKP > PAP > PSP. Therefore, although the polysaccharide fractions had little effect on superoxide radical scavenging, they still have potential to be developed as natural antioxidant agents in functional foods or medicine.

  6. Composition and antioxidant activities of four polysaccharides extracted from Herba Lophatheri.

    Science.gov (United States)

    Ge, Qing; Mao, Jian-wei; Guo, Xiao-qing; Zhou, Yi-feng; Gong, Jing-yan; Mao, Shuang-rong

    2013-09-01

    Four polysaccharides (BLF80-A, BLF80-B, BLF80-C and BLF80-D) were isolated by hot-water extraction and purified from the leaves of Herba Lophatheri by DEAE-Sepharose fast flow. Their chemical and physical characteristics were determined and antioxidant activities were investigated on the basis of DPPH radical assay, hydroxyl radical assay and superoxide radical assay. The results showed that four polysaccharides exhibited antioxidant activities in a concentration-dependent manner, and the higher molecular weight, the stronger antioxidant activities of polysaccharides. Besides, the monosaccharide compositions of polysaccharides also influence their antioxidant activities. BLP80-D showed the strongest scavenging ability, followed by BLP80-C, BLP80-B and BLP80-A. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Cell Wall Composition and Candidate Biosynthesis Gene Expression During Rice Development

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Fan; Manisseri, Chithra; Fagerström, Alexandra; Peck, Matthew L.; Vega-Sánchez, Miguel E.; Williams, Brian; Chiniquy, Dawn M.; Saha, Prasenjit; Pattathil, Sivakumar; Conlin, Brian; Zhu, Lan; Hahn, Michael G.; Willats, William G. T.; Scheller, Henrik V.; Ronald, Pamela C.; Bartley, Laura E.

    2016-08-01

    Cell walls of grasses, including cereal crops and biofuel grasses, comprise the majority of plant biomass and intimately influence plant growth, development and physiology. However, the functions of many cell wall synthesis genes, and the relationships among and the functions of cell wall components remain obscure. To better understand the patterns of cell wall accumulation and identify genes that act in grass cell wall biosynthesis, we characterized 30 samples from aerial organs of rice (Oryza sativa cv. Kitaake) at 10 developmental time points, 3-100 d post-germination. Within these samples, we measured 15 cell wall chemical components, enzymatic digestibility and 18 cell wall polysaccharide epitopes/ligands. We also used quantitative reverse transcription-PCR to measure expression of 50 glycosyltransferases, 15 acyltransferases and eight phenylpropanoid genes, many of which had previously been identified as being highly expressed in rice. Most cell wall components vary significantly during development, and correlations among them support current understanding of cell walls. We identified 92 significant correlations between cell wall components and gene expression and establish nine strong hypotheses for genes that synthesize xylans, mixed linkage glucan and pectin components. This work provides an extensive analysis of cell wall composition throughout rice development, identifies genes likely to synthesize grass cell walls, and provides a framework for development of genetically improved grasses for use in lignocellulosic biofuel production and agriculture.

  8. Genetic and environmental factors contribute to variation in cell wall composition in mature desi chickpea (Cicer arietinum L.) cotyledons.

    Science.gov (United States)

    Wood, Jennifer A; Tan, Hwei-Ting; Collins, Helen M; Yap, Kuok; Khor, Shi Fang; Lim, Wai Li; Xing, Xiaohui; Bulone, Vincent; Burton, Rachel A; Fincher, Geoffrey B; Tucker, Matthew R

    2018-03-13

    Chickpea (Cicer arietinum L.) is an important nutritionally rich legume crop that is consumed worldwide. Prior to cooking, desi chickpea seeds are most often dehulled and cleaved to release the split cotyledons, referred to as dhal. Compositional variation between desi genotypes has a significant impact on nutritional quality and downstream processing, and this has been investigated mainly in terms of starch and protein content. Studies in pulses such as bean and lupin have also implicated cell wall polysaccharides in cooking time variation, but the underlying relationship between desi chickpea cotyledon composition and cooking performance remains unclear. Here, we utilized a variety of chemical and immunohistological assays to examine details of polysaccharide composition, structure, abundance, and location within the desi chickpea cotyledon. Pectic polysaccharides were the most abundant cell wall components, and differences in monosaccharide and glycosidic linkage content suggest both environmental and genetic factors contribute to cotyledon composition. Genotype-specific differences were identified in arabinan structure, pectin methylesterification, and calcium-mediated pectin dimerization. These differences were replicated in distinct field sites and suggest a potentially important role for cell wall polysaccharides and their underlying regulatory machinery in the control of cooking time in chickpea. © 2018 The Authors. Plant, Cell & Environment Published by John Wiley & Sons Ltd.

  9. Effect of okra cell wall and polysaccharide on physical properties and stability of ice cream.

    Science.gov (United States)

    Yuennan, Pilapa; Sajjaanantakul, Tanaboon; Goff, H Douglas

    2014-08-01

    Stabilizers are used in ice cream to increase mix viscosity, promote smooth texture, and improve frozen stability. In this study, the effects of varying concentrations (0.00%, 0.15%, 0.30%, and 0.45%) of okra cell wall (OKW) and its corresponding water-soluble polysaccharide (OKP) on the physical characteristics of ice cream were determined. Ice cream mix viscosity was measured as well as overrun, meltdown, and consumer acceptability. Ice recrystallization was determined after ice cream was subjected to temperature cycling in the range of -10 to -20 °C for 10 cycles. Mix viscosity increased significantly as the concentrations of OKW and OKP increased. The addition of either OKW or OKP at 0.15% to 0.45% significantly improved the melting resistance of ice cream. OKW and OKP at 0.15% did not affect sensory perception score for flavor, texture, and overall liking of the ice cream. OKW and OKP (0.15%) reduced ice crystal growth to 107% and 87%, respectively, as compared to 132% for the control (0.00%). Thus, our results suggested the potential use of OKW and OKP at 0.15% as a stabilizer to control ice cream quality and retard ice recrystallization. OKP, however, at 0.15% exhibited greater effect on viscosity increase and on ice recrystallization inhibition than OKW. © 2014 Institute of Food Technologists®

  10. The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens.

    Directory of Open Access Journals (Sweden)

    Isabel E Moller

    Full Text Available The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus degrades cellulose have hampered our understanding of the selection forces that induced large scale herbivory and of the ensuing ecological footprint of these ants. Here we use a recently established technique, based on polysaccharide microarrays probed with antibodies and carbohydrate binding modules, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste material that the ants remove from their fungus garden. These results demonstrate that biomass entering leaf-cutting ant fungus gardens is only partially utilized and explain why disproportionally large amounts of plant material are needed to sustain colony growth. They also explain why substantial communities of microbial and invertebrate symbionts have evolved associations with the dump material from leaf-cutting ant nests, to exploit decomposition niches that the ant garden-fungus does not utilize. Our approach thus provides detailed insight into the nutritional benefits and shortcomings associated with fungus-farming in ants.

  11. Engineering temporal accumulation of a low recalcitrance polysaccharide leads to increased C6 sugar content in plant cell walls

    Energy Technology Data Exchange (ETDEWEB)

    Vega-Sánchez, Miguel E. [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Loqué, Dominique [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Lao, Jeemeng [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Catena, Michela [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Verhertbruggen, Yves [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Herter, Thomas [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Yang, Fan [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Harholt, Jesper [Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C Denmark; Ebert, Berit [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C Denmark; Baidoo, Edward E. K. [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Keasling, Jay D. [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Department of Chemical and Biomolecular Engineering, and Department of Bioengineering, University of California, Berkeley CA USA; Scheller, Henrik V. [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Department of Plant and Microbial Biology, University of California, Berkeley CA USA; Heazlewood, Joshua L. [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Ronald, Pamela C. [Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA USA; Department of Plant Pathology and the Genome Center, University of California, Davis CA USA

    2015-01-14

    Reduced cell wall recalcitrance and increased C6 monosaccharide content are desirable traits for future biofuel crops, as long as these biomass modifications do not significantly alter normal growth and development. Mixed-linkage glucan (MLG), a cell wall polysaccharide only present in grasses and related species among flowering plants, is comprised of glucose monomers linked by both β-1,3 and β-1,4 bonds. Previous data have shown that constitutive production of MLG in barley (Hordeum vulgare) severely compromises growth and development. Here, we used spatio-temporal strategies to engineer Arabidopsis thaliana plants to accumulate significant amounts of MLG in the cell wall by expressing the rice CslF6 MLG synthase using secondary cell wall and senescence-associated promoters. Results using secondary wall promoters were suboptimal. When the rice MLG synthase was expressed under the control of a senescence-associated promoter, we obtained up to four times more glucose in the matrix cell wall fraction and up to a 42% increase in saccharification compared to control lines. Importantly, these plants grew and developed normally. The induction of MLG deposition at senescence correlated with an increase of gluconic acid in cell wall extracts of transgenic plants in contrast to the other approaches presented in this study. MLG produced in Arabidopsis has an altered structure compared to the grass glucan, which likely affects its solubility, while its molecular size is unaffected. The induction of cell wall polysaccharide biosynthesis in senescing tissues offers a novel engineering alternative to enhance cell wall properties of lignocellulosic biofuel crops.

  12. Composite asymptotic expansions and scaling wall turbulence.

    Science.gov (United States)

    Panton, Ronald L

    2007-03-15

    In this article, the assumptions and reasoning that yield composite asymptotic expansions for wall turbulence are discussed. Particular attention is paid to the scaling quantities that are used to render the variables non-dimensional and of order one. An asymptotic expansion is proposed for the streamwise Reynolds stress that accounts for the active and inactive turbulence by using different scalings. The idea is tested with the data from the channel flows and appears to have merit.

  13. Genetics and physiology of cell wall polysaccharides in the model C4 grass, Setaria viridis spp.

    Science.gov (United States)

    Ermawar, Riksfardini A; Collins, Helen M; Byrt, Caitlin S; Henderson, Marilyn; O'Donovan, Lisa A; Shirley, Neil J; Schwerdt, Julian G; Lahnstein, Jelle; Fincher, Geoffrey B; Burton, Rachel A

    2015-10-02

    Setaria viridis has emerged as a model species for the larger C4 grasses. Here the cellulose synthase (CesA) superfamily has been defined, with an emphasis on the amounts and distribution of (1,3;1,4)-β-glucan, a cell wall polysaccharide that is characteristic of the grasses and is of considerable value for human health. Orthologous relationship of the CesA and Poales-specific cellulose synthase-like (Csl) genes among Setaria italica (Si), Sorghum bicolor (Sb), Oryza sativa (Os), Brachypodium distachyon (Bradi) and Hordeum vulgare (Hv) were compared using bioinformatics analysis. Transcription profiling of Csl gene families, which are involved in (1,3;1,4)-β-glucan synthesis, was performed using real-time quantitative PCR (Q-PCR). The amount of (1,3;1,4)-β-glucan was measured using a modified Megazyme assay. The fine structures of the (1,3;1,4)-β-glucan, as denoted by the ratio of cellotriosyl to cellotetraosyl residues (DP3:DP4 ratio) was assessed by chromatography (HPLC and HPAEC-PAD). The distribution and deposition of the MLG was examined using the specific antibody BG-1 and captured using fluorescence and transmission electron microscopy (TEM). The cellulose synthase gene superfamily contains 13 CesA and 35 Csl genes in Setaria. Transcript profiling of CslF, CslH and CslJ gene families across a vegetative tissue series indicated that SvCslF6 transcripts were the most abundant relative to all other Csl transcripts. The amounts of (1,3;1,4)-β-glucan in Setaria vegetative tissues ranged from 0.2% to 2.9% w/w with much smaller amounts in developing grain (0.003% to 0.013% w/w). In general, the amount of (1,3;1,4)-β-glucan was greater in younger than in older tissues. The DP3:DP4 ratios varied between tissue types and across developmental stages, and ranged from 2.4 to 3.0:1. The DP3:DP4 ratios in developing grain ranged from 2.5 to 2.8:1. Micrographs revealing the distribution of (1,3;1,4)-β-glucan in walls of different cell types and the data were

  14. Plant-based foods containing cell wall polysaccharides rich in specific active monosaccharides protect against myocardial injury in rat myocardial infarction models.

    Science.gov (United States)

    Lim, Sun Ha; Kim, Yaesil; Yun, Ki Na; Kim, Jin Young; Jang, Jung-Hee; Han, Mee-Jung; Lee, Jongwon

    2016-12-08

    Many cohort studies have shown that consumption of diets containing a higher composition of foods derived from plants reduces mortality from coronary heart disease (CHD). Here, we examined the active components of a plant-based diet and the underlying mechanisms that reduce the risk of CHD using three rat models and a quantitative proteomics approach. In a short-term myocardial infarction (MI) model, intake of wheat extract (WE), the representative cardioprotectant identified by screening approximately 4,000 samples, reduced myocardial injury by inhibiting apoptosis, enhancing ATP production, and maintaining protein homeostasis. In long-term post-MI models, this myocardial protection resulted in ameliorating adverse left-ventricular remodelling, which is a predictor of heart failure. Among the wheat components, arabinose and xylose were identified as active components responsible for the observed efficacy of WE, which was administered via ingestion and tail-vein injections. Finally, the food components of plant-based diets that contained cell wall polysaccharides rich in arabinose, xylose, and possibly fucose were found to confer protection against myocardial injury. These results show for the first time that specific monosaccharides found in the cell wall polysaccharides in plant-based diets can act as active ingredients that reduce CHD by inhibiting postocclusion steps, including MI and heart failure.

  15. Synthesis, Structural, and Adsorption Properties and Thermal Stability of Nanohydroxyapatite/Polysaccharide Composites.

    Science.gov (United States)

    Skwarek, Ewa; Goncharuk, Olena; Sternik, Dariusz; Janusz, Wladyslaw; Gdula, Karolina; Gun'ko, Vladimir M

    2017-12-01

    A series of composites based on nanohydroxyapatite (nHAp) and natural polysaccharides (PS) (nHAp/agar, nHAp/chitosan, nHAp/pectin FB300, nHAp/pectin APA103, nHAp/sodium alginate) was synthesized by liquid-phase two-step method and characterized using nitrogen adsorption-desorption, DSC, TG, FTIR spectroscopy, and SEM. The analysis of nitrogen adsorption-desorption data shows that composites with a nHAp: PS ratio of 4:1 exhibit a sufficiently high specific surface area from 49 to 82 m 2 /g. The incremental pore size distributions indicate mainly mesoporosity. The composites with the component ratio 1:1 preferably form a film-like structure, and the value of S BET varies from 0.3 to 43 m 2 /g depending on the nature of a polysaccharide. Adsorption of Sr(II) on the composites from the aqueous solutions has been studied. The thermal properties of polysaccharides alone and in nHAp/PS show the influence of nHAp, since there is a shift of characteristic DSC and DTG peaks. FTIR spectroscopy data confirm the presence of functional groups typical for nHAp as well as polysaccharides in composites. Structure and morphological characteristics of the composites are strongly dependent on the ratio of components, since nHAp/PS at 4:1 have relatively large S BET values and a good ability to adsorb metal ions. The comparison of the adsorption capacity with respect to Sr(II) of nHAp, polysaccharides, and composites shows that it of the latter is higher than that of nHAp (per 1 m 2 of surface).

  16. Chemical characterisation and analysis of the cell wall polysaccharides of duckweed (Lemna minor).

    Science.gov (United States)

    Zhao, X; Moates, G K; Wellner, N; Collins, S R A; Coleman, M J; Waldron, K W

    2014-10-13

    Duckweed is potentially an ideal biofuel feedstock due to its high proportion of cellulose and starch and low lignin content. However, there is little detailed information on the composition and structure of duckweed cell walls relevant to optimising the conversion of duckweed biomass to ethanol and other biorefinery products. This study reports that, for the variety and batch evaluated, carbohydrates constitute 51.2% (w/w) of dry matter while starch accounts for 19.9%. This study, for the first time, analyses duckweed cell wall composition through a detailed sequential extraction. The cell wall is rich in cellulose and also contains 20.3% pectin comprising galacturonan, xylogalacturonan, rhamnogalacturonan; 3.5% hemicellulose comprising xyloglucan and xylan, and 0.03% phenolics. In addition, essential fatty acids (0.6%, α-linolenic and linoleic/linoelaidic acid) and p-coumaric acid (0.015%) respectively are the most abundant fatty acids and phenolics in whole duckweed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Immuno and affinity cytochemical analysis of cell wall composition in the moss Physcomitrella patens

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Berry

    2016-03-01

    Full Text Available In contrast to homeohydric vascular plants, mosses employ a poikilohydric strategy for surviving in the dry aerial environment. A detailed understanding of the structure, composition, and development of moss cell walls can contribute to our understanding of not only the evolution of overall cell wall complexity, but also the differences that have evolved in response to selection for different survival strategies. The model moss species Physcomitrella patens has a predominantly haploid lifecycle consisting of protonemal filaments that regenerate from protoplasts and enlarge by tip growth, and leafy gametophores composed of cells that enlarge by diffuse growth and differentiate into several different types. Advantages for genetic studies include methods for efficient targeted gene modification and extensive genomic resources. Immuno and affinity cytochemical labeling were used to examine the distribution of polysaccharides and proteins in regenerated protoplasts, protonemal filaments, rhizoids, and sectioned gametophores of P. patens. The cell wall composition of regenerated protoplasts was also characterized by flow cytometry. Crystalline cellulose was abundant in the cell walls of regenerating protoplasts and protonemal cells that developed on media of high osmolarity, whereas homogalacturonan was detected in the walls of protonemal cells that developed on low osmolarity media and not in regenerating protoplasts. Mannan was the major hemicellulose detected in all tissues tested. Arabinogalactan proteins were detected in different cell types by different probes, consistent with structural heterogeneity. The results reveal developmental and cell type specific differences in cell wall composition and provide a basis for analyzing cell wall phenotypes in knockout mutants.

  18. Haze in Apple-Based Beverages: Detailed Polyphenol, Polysaccharide, Protein, and Mineral Compositions.

    Science.gov (United States)

    Millet, Melanie; Poupard, Pascal; Le Quéré, Jean-Michel; Bauduin, Remi; Guyot, Sylvain

    2017-08-09

    Producers of apple-based beverages are confronted with colloidal instability. Haze is caused by interactions between molecules that lead to the formation of aggregates. Haze composition in three apple-based beverages, namely, French sparkling cider, apple juice, and pommeau, was studied. Phenolic compounds, proteins, polysaccharides, and minerals were analyzed using global and detailed analytical methods. The results explained apple juice hazes, where they were the main constituents (18 and 24%). Polysaccharides accounted for 0-30% of haze. Potassium and calcium were the main minerals.

  19. A Clostridium difficile Cell Wall Glycopolymer Locus Influences Bacterial Shape, Polysaccharide Production and Virulence.

    Directory of Open Access Journals (Sweden)

    Michele Chu

    2016-10-01

    Full Text Available Clostridium difficile is a diarrheagenic pathogen associated with significant mortality and morbidity. While its glucosylating toxins are primary virulence determinants, there is increasing appreciation of important roles for non-toxin factors in C. difficile pathogenesis. Cell wall glycopolymers (CWGs influence the virulence of various pathogens. Five C. difficile CWGs, including PSII, have been structurally characterized, but their biosynthesis and significance in C. difficile infection is unknown. We explored the contribution of a conserved CWG locus to C. difficile cell-surface integrity and virulence. Attempts at disrupting multiple genes in the locus, including one encoding a predicted CWG exporter mviN, were unsuccessful, suggesting essentiality of the respective gene products. However, antisense RNA-mediated mviN downregulation resulted in slight morphology defects, retarded growth, and decreased surface PSII deposition. Two other genes, lcpA and lcpB, with putative roles in CWG anchoring, could be disrupted by insertional inactivation. lcpA- and lcpB- mutants had distinct phenotypes, implying non-redundant roles for the respective proteins. The lcpB- mutant was defective in surface PSII deposition and shedding, and exhibited a remodeled cell surface characterized by elongated and helical morphology, aberrantly-localized cell septae, and an altered surface-anchored protein profile. Both lcpA- and lcpB- strains also displayed heightened virulence in a hamster model of C. difficile disease. We propose that gene products of the C. difficile CWG locus are essential, that they direct the production/assembly of key antigenic surface polysaccharides, and thereby have complex roles in virulence.

  20. Compositional analysis of sulfated polysaccharides from sea cucumber (Stichopus japonicus) released by autolysis reaction.

    Science.gov (United States)

    Song, Shuang; Wu, Sufeng; Ai, Chunqing; Xu, Xin; Zhu, Zhenjun; Cao, Chunyang; Yang, Jingfeng; Wen, Chengrong

    2018-07-15

    Autolysis is not only a major reason for postharvest quality deterioration of sea cucumber, but also a promising alternative for exogenous protease to produce peptides or polysaccharides. However, little has been known about the effects of autolysis on bioactive polysaccharides of sea cucumber. Concerning the quality and safety of sea cucumber products involved autolysis reaction, the present study focused on the chemical composition of sulfated polysaccharides (SPs) released by autolysis reaction. Chemical analysis indicated that after 3-day autolysis 63% of sulfated polysaccharides were liberated but with protein chains at their reducing ends. Then the composition of SP obtained by autolysis (A-SP) was compared with that of total SPs (T-SP) via a series of analysis techniques, including FTIR, 1 H NMR, HPLC and mass spectroscopy. As indicated by the results, fucan to fucosylated chondroitin sulfate ratio was found high in A-SP compared to T-SP, fucan with a lower molecular weight was the major fraction in A-SP, and the di-sulfated Fuc residue observed in T-SP was absent in A-SP. To conclude, A-SP differed greatly from T-SP in the chemical composition, suggesting possible changes on their bioactivities. Copyright © 2018. Published by Elsevier B.V.

  1. Identification and characterization of glycosyltransferases involved in the synthesis of the side chains of the cell wall pectic polysaccharide rhamnogalacturonan II

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, Malcolm [Univ. of Georgia, Athens, GA (United States)

    2015-08-31

    Our goal was to gain insight into the genes and proteins involved in the biosynthesis of rhamnogalacturonan II (RG-II), a borate cross-linked and structurally conserved pectic polysaccharide present in the primary cell walls of all vascular plants. The research conducted during the funding period established that (i) Avascular plants have the ability to synthesize UDP-apiose but lack the glycosyltransferase machinery required to synthesize RG-II or other apiose-containing cell wall glycans. (ii) RG-II structure is highly conserved in the Lemnaceae (duckweeds and relatives). However, the structures of other wall pectins and hemicellulose have changed substantial during the diversification of the Lemnaceae. This supports the notion that a precise structure of RG-II must be maintained to allow borate cross-linking to occur in a controlled manner. (iii) Enzymes involved in the conversion of UDP-GlcA to UDP-Api, UDP-Xyl, and UDP-Ara may have an important role in controlling the composition of duckweed cell walls. (iv) RG-II exists as the borate ester cross-linked dimer in the cell walls of soybean root hairs and roots. Thus, RG-II is present in the walls of plants cells that grow by tip or by expansive growth. (v) A reduction in RG-II cross-linking in the maize tls1 mutant, which lacks a borate channel protein, suggests that the growth defects observed in the mutant are, at least in part, due to defects in the cell wall.

  2. Sticking to cellulose: exploiting Arabidopsis seed coat mucilage to understand cellulose biosynthesis and cell wall polysaccharide interactions.

    Science.gov (United States)

    Griffiths, Jonathan S; North, Helen M

    2017-05-01

    The cell wall defines the shape of cells and ultimately plant architecture. It provides mechanical resistance to osmotic pressure while still being malleable and allowing cells to grow and divide. These properties are determined by the different components of the wall and the interactions between them. The major components of the cell wall are the polysaccharides cellulose, hemicellulose and pectin. Cellulose biosynthesis has been extensively studied in Arabidopsis hypocotyls, and more recently in the mucilage-producing epidermal cells of the seed coat. The latter has emerged as an excellent system to study cellulose biosynthesis and the interactions between cellulose and other cell wall polymers. Here we review some of the major advances in our understanding of cellulose biosynthesis in the seed coat, and how mucilage has aided our understanding of the interactions between cellulose and other cell wall components required for wall cohesion. Recently, 10 genes involved in cellulose or hemicellulose biosynthesis in mucilage have been identified. These discoveries have helped to demonstrate that xylan side-chains on rhamnogalacturonan I act to link this pectin directly to cellulose. We also examine other factors that, either directly or indirectly, influence cellulose organization or crystallization in mucilage. © 2017 INRA. New Phytologist © 2017 New Phytologist Trust.

  3. Alfalfa stem tissues: Cell wall deposition, composition, and degradability

    NARCIS (Netherlands)

    Jung, H.G.; Engels, F.M.

    2002-01-01

    Declining cell wall degradability of alfalfa (Medicago sativa L.) stems with maturation limits the nutritional value of alfalfa for ruminants. This study characterized changes in cell wall concentration, composition, and degradability by rumen microbes resulting from alfalfa stem tissue

  4. Composite steel panels for tornado missile barrier walls. Topical report

    International Nuclear Information System (INIS)

    1975-10-01

    A composite steel panel wall system is defined as a wall system with concrete fill sandwiched between two steel layers such that no concrete surface is exposed on the interior or the exterior wall surface. Three full scale missile tests were conducted on two specific composite wall systems. The results of the full scale tests were in good agreement with the finalized theory. The theory is presented, and the acceptance of the theory for design calculations is discussed

  5. Bioactive Mushroom Polysaccharides: A Review on Monosaccharide Composition, Biosynthesis and Regulation.

    Science.gov (United States)

    Wang, Qiong; Wang, Feng; Xu, Zhenghong; Ding, Zhongyang

    2017-06-13

    Mushrooms are widely distributed around the world and are heavily consumed because of their nutritional value and medicinal properties. Polysaccharides (PSs) are an important component of mushrooms, a major factor in their bioactive properties, and have been intensively studied during the past two decades. Monosaccharide composition/combinations are important determinants of PS bioactivities. This review summarizes: (i) monosaccharide composition/combinations in various mushroom PSs, and their relationships with PS bioactivities; (ii) possible biosynthetic pathways of mushroom PSs and effects of key enzymes on monosaccharide composition; (iii) regulation strategies in PS biosynthesis, and prospects for controllable biosynthesis of PSs with enhanced bioactivities.

  6. Analysis of compositional monosaccharides in fungus polysaccharides by capillary zone electrophoresis.

    Science.gov (United States)

    Hu, Yuanyuan; Wang, Tong; Yang, Xingbin; Zhao, Yan

    2014-02-15

    A rapid analytical method of capillary zone electrophoresis (CZE) was established for the simultaneous separation and determination of 10 monosaccharides (aldoses and uronic acids). The monosaccharides were labeled with 1-phenyl-3-methyl-5-pyrazolone (PMP), and subsequently separated using an uncoated capillary (50 μm i.d. × 58.5 cm) and detected by UV at 245 nm with pH 11.0, 175 mM borate buffer at voltage 20 kV and capillary temperature 25 °C by CZE. The 10 PMP-labeled monosaccharides were rapidly baseline separated within 20 min. The optimized CZE method was successfully applied to the simultaneous separation and identification of the monosaccharide composition in Termitomyces albuminosus polysaccharides (TAPs) and Panus giganteus polysaccharides (PGPs). The quantitative recovery of the component monosaccharides in the fungus polysaccharides was in the range of 92.0-101.0% and the CV value was lower than 3.5%. The results demonstrate that the proposed CZE method is precise and practical for the monosaccharide analysis of fungus polysaccharides. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Cell wall matrix polysaccharide distribution and cortical microtubule organization: two factors controlling mesophyll cell morphogenesis in land plants.

    Science.gov (United States)

    Sotiriou, P; Giannoutsou, E; Panteris, E; Apostolakos, P; Galatis, B

    2016-03-01

    This work investigates the involvement of local differentiation of cell wall matrix polysaccharides and the role of microtubules in the morphogenesis of mesophyll cells (MCs) of three types (lobed, branched and palisade) in the dicotyledon Vigna sinensis and the fern Asplenium nidus. Homogalacturonan (HGA) epitopes recognized by the 2F4, JIM5 and JIM7 antibodies and callose were immunolocalized in hand-made leaf sections. Callose was also stained with aniline blue. We studied microtubule organization by tubulin immunofluorescence and transmission electron microscopy. In both plants, the matrix cell wall polysaccharide distribution underwent definite changes during MC differentiation. Callose constantly defined the sites of MC contacts. The 2F4 HGA epitope in V. sinensis first appeared in MC contacts but gradually moved towards the cell wall regions facing the intercellular spaces, while in A. nidus it was initially localized at the cell walls delimiting the intercellular spaces, but finally shifted to MC contacts. In V. sinensis, the JIM5 and JIM7 HGA epitopes initially marked the cell walls delimiting the intercellular spaces and gradually shifted in MC contacts, while in A. nidus they constantly enriched MC contacts. In all MC types examined, the cortical microtubules played a crucial role in their morphogenesis. In particular, in palisade MCs, cortical microtubule helices, by controlling cellulose microfibril orientation, forced these MCs to acquire a truncated cone-like shape. Unexpectedly in V. sinensis, the differentiation of colchicine-affected MCs deviated completely, since they developed a cell wall ingrowth labyrinth, becoming transfer-like cells. The results of this work and previous studies on Zea mays (Giannoutsou et al., Annals of Botany 2013; 112: : 1067-1081) revealed highly controlled local cell wall matrix differentiation in MCs of species belonging to different plant groups. This, in coordination with microtubule-dependent cellulose microfibril

  8. Structural characteristics of polysaccharides from olive fruit cell walls in relation to ripening and processing

    NARCIS (Netherlands)

    Vierhuis, E.

    2002-01-01

    Key words: Olive fruit; olive oil; pectic polysaccharides; xyloglucans; xylans;

    enzyme preparations; phenolic compounds; processing; ripening

    Technical enzyme preparations can be used as processing aids in the olive oil industry to obtain a higher yield

  9. Impact of 4 Lactobacillus plantarum capsular polysaccharide clusters on surface glycan composition and host cell signaling

    Directory of Open Access Journals (Sweden)

    Remus Daniela M

    2012-11-01

    Full Text Available Abstract Background Bacterial cell surface-associated polysaccharides are involved in the interactions of bacteria with their environment and play an important role in the communication between pathogenic bacteria and their host organisms. Cell surface polysaccharides of probiotic species are far less well described. Therefore, improved knowledge on these molecules is potentially of great importance to understand the strain-specific and proposed beneficial modes of probiotic action. Results The Lactobacillus plantarum WCFS1 genome encodes 4 clusters of genes that are associated with surface polysaccharide production. Two of these clusters appear to encode all functions required for capsular polysaccharide formation (cps2A-J and cps4A-J, while the remaining clusters are predicted to lack genes encoding chain-length control functions and a priming glycosyl-transferase (cps1A-I and cps3A-J. We constructed L. plantarum WCFS1 gene deletion mutants that lack individual (Δcps1A-I, Δcps2A-J, Δcps3A-J and Δcps4A-J or combinations of cps clusters (Δcps1A-3J and Δcps1A-3I, Δcps4A-J and assessed the genome wide impact of these mutations by transcriptome analysis. The cps cluster deletions influenced the expression of variable gene sets in the individual cps cluster mutants, but also considerable numbers of up- and down-regulated genes were shared between mutants in cps cluster 1 and 2, as well as between mutant in cps clusters 3 and 4. Additionally, the composition of overall cell surface polysaccharide fractions was altered in each mutant strain, implying that despite the apparent incompleteness of cps1A-I and cps3A-J, all clusters are active and functional in L. plantarum. The Δcps1A-I strain produced surface polysaccharides in equal amounts as compared to the wild-type strain, while the polysaccharides were characterized by a reduced molar mass and the lack of rhamnose. The mutants that lacked functional copies of cps2A-J, cps3A-J or cps4A

  10. Soya beans and maize : the effect of chemical and physical structure of cell wall polysaccharides on fermentation kinetics

    NARCIS (Netherlands)

    Laar, van H.

    2000-01-01

    The analysis of the relationship between cell wall composition and fermentation of endosperm cell walls of soya beans and maize was approached from three different angles. Firstly, the fermentation (rate and extent of fermentation, the sugar degradation pattern, and volatile fatty acid

  11. Auxin-induced modifications of cell wall polysaccharides in cat coleoptile segments. Effect of galactose

    International Nuclear Information System (INIS)

    Yamamoto, R.; Masuda, Y.

    1984-01-01

    Galactose inhibits auxin-induced cell elongation in oat coleoptile segments. Cell elongation induced by exogenously applied auxin is controlled by factors such as auxin uptake, cell wall loosening, osmotic concentration of sap and hydraulic conductivity. However, galactose does not have any effect on these factors. The results discussed in this paper led to the conclusion that galactose does not affect cell wall loosening which controls rapid growth, but inhibits cell wall synthesis which is required to maintain long-term growth

  12. Investigation of the Relationship between Lactococcal Host Cell Wall Polysaccharide Genotype and 936 Phage Receptor Binding Protein Phylogeny

    DEFF Research Database (Denmark)

    Mahony, Jennifer; Kot, Witold Piotr; Murphy, James

    2013-01-01

    Comparative genomics of 11 lactococcal 936-type phages combined with host range analysis allowed subgrouping of these phage genomes, particularly with respect to their encoded receptor binding proteins. The so-called pellicle or cell wall polysaccharide of Lactococcus lactis, which has been...... implicated as a host receptor of (certain) 936-type phages, is specified by a large gene cluster, which, among different lactococcal strains, contains highly conserved regions as well as regions of diversity. The regions of diversity within this cluster on the genomes of lactococcal strains MG1363, SK11, IL......1403, KF147, CV56, and UC509.9 were used for the development of a multiplex PCR system to identify the pellicle genotype of lactococcal strains used in this study. The resulting comparative analysis revealed an apparent correlation between the pellicle genotype of a given host strain and the host range...

  13. Synthesis of branched–backbone oligosaccharides of the pectic RG-I plant cell wall polysaccharide

    DEFF Research Database (Denmark)

    Awan, Shahid Iqbal; Clausen, Mads Hartvig

    with numerous branches of galactan, arabinan, or arabinogalactan positioned at C-4 of the rhamnose residues. The use of defined oligosaccharides rather than isolated polysaccharides can aid in obtaining detailedinformation about biosynthetic pathways, plant evolution, and agronomical properties. Furthermore......,biological testing can provide new insight into plant biology; important for plant preservation, engineering,and utilization of plants as a source of bioenergy. Present work towards defined RG-I substructures involvesa [4+3]-coupling to furnish a heptasaccharide backbone unit (see Figure 1). Moreover, installation...

  14. Strengthening masonry walls made of brick blocks with FRCM composites

    Directory of Open Access Journals (Sweden)

    Radovanović Željka

    2015-01-01

    Full Text Available Results of testing more types of masonry walls made of brick blocks with the aim to define their mechanical characteristics and possibilities of external strengthening of walls with FRCM composites are presented in this paper. The characteristic compressive strengths, elasticity modulus and shear strengths of the various types of the walls were obtained on the basis of these testing results. Comparison between experimental results and values obtained by analytical approach in accordance with the current standard, European standards EN 1996 and the American standard ACI 530 is presented in this paper. After testing walls with application of compressive forces on the walls diagonal the cracked walls samples have been strengthened with selected types of FRCM composites. It was determined that the shear resistance of the walls after strengthening has increased significantly.

  15. Fermentation characteristics of polysaccharide fractions extracted from the cell walls of soya bean cotyledons

    NARCIS (Netherlands)

    Laar, van H.; Tamminga, S.; Williams, B.A.; Verstegen, M.W.A.; Schols, H.A.

    2000-01-01

    Full-fat soya beans were separated into hulls and cotyledons. After separation the cell wall fraction was extracted from the cotyledons. These purified cell walls were sequentially extracted with 0.05 M cyclohexane-trans-1,2-diamine-N,N,N ,N -tetraacetate (CDTA) 0.05 M NH4 oxalate (extract 1), 0.05

  16. N-acetylglucosamine affects Cryptococcus neoformans cell-wall composition and melanin architecture.

    Science.gov (United States)

    Camacho, Emma; Chrissian, Christine; Cordero, Radames J B; Liporagi-Lopes, Livia; Stark, Ruth E; Casadevall, Arturo

    2017-11-01

    Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis. Recent studies have suggested additional roles for GlcNAc as an activator and mediator of cellular signalling in fungal and plant cells. Furthermore, chitin and chitosan polysaccharides interact with melanin pigments in the cell wall and have been found to be essential for melanization. Despite the importance of melanin, its molecular structure remains unresolved; however, we previously obtained critical insights using advanced nuclear magnetic resonance (NMR) and imaging techniques. In this study, we investigated the effect of GlcNAc supplementation on cryptococcal cell-wall composition and melanization. C. neoformans was able to metabolize GlcNAc as a sole source of carbon and nitrogen, indicating a capacity to use a component of a highly abundant polymer in the biospherenutritionally. C. neoformans cells grown with GlcNAc manifested changes in the chitosan cell-wall content, cell-wall thickness and capsule size. Supplementing cultures with isotopically 15 N-labelled GlcNAc demonstrated that the exogenous monomer serves as a building block for chitin/chitosan and is incorporated into the cell wall. The altered chitin-to-chitosan ratio had no negative effects on the mother-daughter cell separation; growth with GlcNAc affected the fungal cell-wall scaffold, resulting in increased melanin deposition and assembly. In

  17. Identification of Bacillus anthracis by Using Monoclonal Antibody to Cell Wall Galactose-N-Acetylglucosamine Polysaccharide

    Science.gov (United States)

    1990-02-01

    Bacillus circulans ATCC 4513 b - - NR NT NT NT NT Bacillus coagulans ATCC 7050 b - - NR NT NT NT NT Bacillus eugilitis B-61 f - - NR NT NT NT NT...American Society for Microbiology W Identification of Bacillus anthracis by-U-sing Monoclonal Antibody CC to Cell Wall Galactose-N-Acetylglucosamine...Received 22 June 1989/Accepted 31 October 1989 ’ Guanidine extracts of crude Bacillus anthracis cell wall were used to vaccinate BALB/c mice and to

  18. Neutral monosaccharide composition analysis of plant-derived oligo- and polysaccharides by high performance liquid chromatography.

    Science.gov (United States)

    Yan, Jun; Shi, Songshan; Wang, Hongwei; Liu, Ruimin; Li, Ning; Chen, Yonglin; Wang, Shunchun

    2016-01-20

    A novel analytical method for neutral monosaccharide composition analysis of plant-derived oligo- and polysaccharides was developed using hydrophilic interaction liquid chromatography coupled to a charged aerosol detector. The effects of column type, additives, pH and column temperature on retention and separation were evaluated. Additionally, the method could distinguish potential impurities in samples, including chloride, sulfate and sodium, from sugars. The results of validation demonstrated that this method had good linearity (R(2) ≥ 0.9981), high precision (relative standard deviation ≤ 4.43%), and adequate accuracy (94.02-103.37% recovery) and sensitivity (detection limit: 15-40 ng). Finally, the monosaccharide compositions of the polysaccharide from Eclipta prostrasta L. and stachyose were successfully profiled through this method. This report represents the first time that all of these common monosaccharides could be well-separated and determined simultaneously by high performance liquid chromatography without additional derivatization. This newly developed method is convenient, efficient and reliable for monosaccharide analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Effect of commercial mannoprotein addition on polysaccharide, polyphenolic, and color composition in red wines.

    Science.gov (United States)

    Guadalupe, Zenaida; Ayestarán, Belén

    2008-10-08

    Commercially available mannoprotein preparations were tested in Tempranillo winemaking to determine their influence on polysaccharide, polyphenolic, and color composition. No effect was found in the content of grape arabinogalactans, homogalacturonans, and type II rhamnogalacturonans. In contrast, mannoprotein-treated samples showed considerably higher values of high-molecular-weight mannoproteins (bMP) than controls from the beginning of alcoholic fermentation, although these differences diminished as vinification progressed. The bMP decrease observed in the mannoprotein-treated samples coincided with a substantial reduction in their proanthocyanidin content and wine stable color, suggesting a precipitation of the coaggregates mannoprotein-tannin and mannoprotein-pigment. Contrary to what is widely described, these results revealed that at the studied conditions, mannoproteins did not act as stabilizing colloids. Mannoprotein addition did not modify the content and composition of either monomeric anthocyanins or other monomeric phenolics, and it did not affect monomeric anthocyanin color.

  20. Titanium dioxide, single-walled carbon nanotube composites

    Science.gov (United States)

    Yao, Yuan; Li, Gonghu; Gray, Kimberly; Lueptow, Richard M.

    2015-07-14

    The present invention provides titanium dioxide/single-walled carbon nanotube composites (TiO.sub.2/SWCNTs), articles of manufacture, and methods of making and using such composites. In certain embodiments, the present invention provides membrane filters and ceramic articles that are coated with TiO.sub.2/SWCNT composite material. In other embodiments, the present invention provides methods of using TiO.sub.2/SWCNT composite material to purify a sample, such as a water or air sample.

  1. Optimization for ultrasound-assisted extraction of polysaccharides with chemical composition and antioxidant activity from the Artemisia sphaerocephala Krasch seeds.

    Science.gov (United States)

    Zheng, Quan; Ren, Daoyuan; Yang, Nana; Yang, Xingbin

    2016-10-01

    Artemisia sphaerocephala Krasch seeds polysaccharides have been reported to have a variety of important biological activities. However, effective extraction of Artemisia sphaerocephala Krasch seeds polysaccharides is still an unsolved issue. In this study, the orthogonal rotatable central composite design was employed to optimize ultrasound-assisted extraction conditions of Artemisia sphaerocephala Krasch seeds polysaccharides. Based on a single-factor analysis method, ultrasonic power, extraction time, solid-liquid ratio and extraction temperature were shown to significantly affect the yield of polysaccharides extracted from the A. sphaerocephala Krasch seeds. The optimal conditions for extraction of Artemisia sphaerocephala Krasch seeds polysaccharides were determined as following: ultrasonic power 243W, extraction time 125min, solid-liquid ratio 64:1 and extraction temperature 64°C, where the experimental yield was 14.78%, which was well matched with the predicted value of 14.81%. Furthermore, ASKP was identified as a typical heteropolysaccharide with d-galacturonic acid (38.8%) d-galactose (20.2%) and d-xylose (15.5%) being the main constitutive monosaccharides. Moreover, Artemisia sphaerocephala Krasch seeds polysaccharides exhibited high total reducing power and considerable scavenging activities on DPPH, hydroxyl and superoxide radicals, in a concentration-dependent manner in vitro. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Development of SPE for recovery of polysaccharides and its application to the determination of monosaccharides composition of the polysaccharide sample of a lactobacillus KLB 58.

    Science.gov (United States)

    Baik, Yoon Suk; Cheong, Won Jo

    2007-07-01

    A new SPE cartridge has been prepared in this study to purify polysaccharides of high molecular weights. A porous nonpolar styrene-divinylbenzene copolymer phase (Hamilton PRP-1) was used to make the new cartridge. The cartridge was conditioned with methanol, water, and ACN in sequence, and the sample dissolved in a small amount of water was loaded. Impurities of low molecular weights were removed first by elution of 80:20 or 90:10 v/v% ACN/water, and polysaccharides were quantitatively recovered by elution of 50:50 v/v% ACN/water or pure water. The recovery of pure dextran 10000 was 90-95%. The SPE method was applied to purification of the polysaccharide sample of KLB58, a new lactobacillus discovered in Korea. The purified KLB 58 sample (weight recovery after SPE purification; 60%) was hydrolyzed for analysis of composition of monosaccharides. The hydrolysate was found to be composed primarily of fructose, glucose, galactose, rhamnose, mannose with small amounts of fucose and ribose.

  3. Structural investigation of cell wall polysaccharides of Lactobacillus delbrueckii subsp. bulgaricus 17.

    Science.gov (United States)

    Vinogradov, E; Sadovskaya, I; Cornelissen, A; van Sinderen, D

    2015-09-02

    Lactobacilli are valuable strains for commercial (functional) food fermentations. Their cell surface-associated polysaccharides (sPSs) possess important functional properties, such as acting as receptors for bacteriophages (bacterial viruses), influencing autolytic characteristics and providing protection against antimicrobial peptides. The current report provides an elaborate molecular description of several surface carbohydrates of Lactobacillus delbrueckii subsp. bulgaricus strain 17. The cell surface of this strain was shown to contain short chain poly(glycerophosphate) teichoic acids and at least two different sPSs, designated here as sPS1 and sPS2, whose chemical structures were examined by 2D nuclear magnetic resonance spectroscopy and methylation analysis. Neutral branched sPS1, extracted with n-butanol, was shown to be composed of hexasaccharide repeating units (-[α-d-Glcp-(1-3)-]-4-β-l-Rhap2OAc-4-β-d-Glcp-[α-d-Galp-(1-3)]-4-α-Rhap-3-α-d-Galp-), while the major component of the TCA-extracted sPS2 was demonstrated to be a linear d-galactan with the repeating unit structure being (-[Gro-3P-(1-6)-]-3-β-Galf-3-α-Galp-2-β-Galf-6-β-Galf-3-β-Galp-). Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Absence of arabinan in the side chains of the pectic polysaccharides strongly associated with cell walls of Nicotiana plumbaginifolia non-organogenic callus with loosely attached constituent cells.

    Science.gov (United States)

    Iwai, H; Ishii, T; Satoh, S

    2001-10-01

    When leaf disks from haploid plants of Nicotiana plumbaginifolia Viv. were transformed with T-DNA and cultured on shoot-inducing medium, nonorganogenic callus. designated nolac (for non-organogenic callus with loosely attached cells), appeared on approximately 7% of leaf disks. In contrast, normal callus was generated on T-DNA-transformed leaf disks from diploid plants and on non-transformed leaf disks from haploid and diploid plants. Transmission electron microscopy revealed that the middle lamellae and the cell walls of one line of mutant callus (nolac-H14) were barely stained by ruthenium red. even after demethylesterification with NaOH, whereas the entire cell wall and the middle lamella were strongly stained in normal callus. In cultures of nolac-H14 callus, the level of sugar components of pectic polysaccharides in the hemicellulose fraction was reduced and that in the culture medium was elevated, as compared with cultures of normal callus. These results indicate that pectic polysaccharides are not retained in the cell walls and middle lamellae of nolac-H14 callus. In nolac-H14, the ratio of arabinose to galactose was low in the pectic polysaccharides purified from all cell wall fractions and from the medium, in particular, in the hemicellulose fractions. The low levels of arabinofuranosyl (T-Araf, 5-Araf, 2,5-Araf, and 3,5-Araf) residues in the pectic polysaccharides of the hemicellulosic fraction of nolac-H,14 indicated that no neutral-sugar side chains, composed mainly of linear arabinan. were present in nolac-H14. Arabinose-rich pectins. which are strongly associated with cellulose-hemicellulose complexes, might play an important role in intercellular attachment in the architecture of the cell wall.

  5. Arabidopsis leucine-rich repeat extensin (LRX) proteins modify cell wall composition and influence plant growth.

    Science.gov (United States)

    Draeger, Christian; Ndinyanka Fabrice, Tohnyui; Gineau, Emilie; Mouille, Grégory; Kuhn, Benjamin M; Moller, Isabel; Abdou, Marie-Therese; Frey, Beat; Pauly, Markus; Bacic, Antony; Ringli, Christoph

    2015-06-24

    Leucine-rich repeat extensins (LRXs) are extracellular proteins consisting of an N-terminal leucine-rich repeat (LRR) domain and a C-terminal extensin domain containing the typical features of this class of structural hydroxyproline-rich glycoproteins (HRGPs). The LRR domain is likely to bind an interaction partner, whereas the extensin domain has an anchoring function to insolubilize the protein in the cell wall. Based on the analysis of the root hair-expressed LRX1 and LRX2 of Arabidopsis thaliana, LRX proteins are important for cell wall development. The importance of LRX proteins in non-root hair cells and on the structural changes induced by mutations in LRX genes remains elusive. The LRX gene family of Arabidopsis consists of eleven members, of which LRX3, LRX4, and LRX5 are expressed in aerial organs, such as leaves and stem. The importance of these LRX genes for plant development and particularly cell wall formation was investigated. Synergistic effects of mutations with gradually more severe growth retardation phenotypes in double and triple mutants suggest a similar function of the three genes. Analysis of cell wall composition revealed a number of changes to cell wall polysaccharides in the mutants. LRX3, LRX4, and LRX5, and most likely LRX proteins in general, are important for cell wall development. Due to the complexity of changes in cell wall structures in the lrx mutants, the exact function of LRX proteins remains to be determined. The increasingly strong growth-defect phenotypes in double and triple mutants suggests that the LRX proteins have similar functions and that they are important for proper plant development.

  6. Evaluation of composite shear walls behavior (parametric study

    Directory of Open Access Journals (Sweden)

    Ali Nikkhoo

    2017-11-01

    Full Text Available Composite shear walls which are made of a layer of steel plate with a concrete cover in one or both sides of the steel plate, are counted as the third generation of the shear walls. Nowadays, composite shear walls are widely utilized in building new resisting structures as well as rehabilitating of the existing structures in earthquake-prone countries. Despite of its advantages, use of the composite shear walls is not yet prevalent as it demands more detailed appropriate investigation. Serving higher strength, flexibility and better energy absorption, while being more economical are the main advantages of this system which has paved its path to be used in high-rise buildings, structural retrofit and reservoir tanks. In this research, channel shear connectors are utilized to connect the concrete cover to the steel plate. As a key parameter, variation in the distance of shear connectors and their arrangement on the behavior of composite shear walls has been scrutinized. In addition, the shear stiffness, flexibility, out of plane displacement and the energy absorption of the structural system has been explored. For this purpose, several structural models with different shear distances and arrangements have been investigated. The obtained results reveal that with increase in shear connectors’ distance, the wall stiffness would reduce while its lateral displacement increases up to eighty percent While the out of plane displacement of the steel plate will reduce up to three times.

  7. New composites of polyaniline and polysaccharides with applications as biomaterials: one review

    Directory of Open Access Journals (Sweden)

    Eliana França

    2007-03-01

    Full Text Available In this revision we will show some results involving composites made with polyaniline and polysaccharides and their properties as promising biomaterials. Studies about the biomedical application of conducting polymers have being considered due the electric stimulation, decrease citotoxicity, good biocompatibility, and others. Polyaniline and polymers derived from the aniline has received attention in the last years by chemical stability in environmental conditions, processibility, facility of polymerization and doping, short cost and particular properties. The botryospheran is an exopolysaccharide (EPS classified in the group of the beta-(1 -3 glucans, produced by the fungus botryosphaeria sp.. EPS has being investigated in parallel about the variability of biological answers of defense. The potential of interaction between conducting polymers with biological environment has been considered, once the application possibilities like development of artificial muscles, nerves regeneration stimulation and medicines delivery control.

  8. Determination of Sugar Composition of Polysaccharides in Caesalpinia pulcherrima Galactomannan Solution Using HPTLC

    Directory of Open Access Journals (Sweden)

    Nilima A. THOMBRE

    2015-04-01

    Full Text Available Galactomannans (GM, a group of neutral nontoxic polysaccharides naturally occurring in the seeds of some legumes, are used in the textile, pharmaceutical, biomedical, cosmetics and food industries. As to date there are no documented reports on determination of the sugar composition in polysaccharides by HPTLC and the following study is an attempt in this direction. GM from seeds of Caesalpinia pulcherrima L. (CP was isolated and purified by precipitation method using alcohol. A new, simple, sensitive, selective, precise, and robust HPTLC method for analysis of monosaccharides such as galactose, mannose, xylose and glucose in isolated CP GM has been developed and validated. Chromatograms were developed using a mobile phase of acetone: water (9:1 v/v on pre-coated plate of silica gel GF aluminium TLC plate and quantified by UV spectrophotometer at 254nm. The Rf values were 0.45, 0.34, 0.40 and 0.60 for mannose, galactose, xylose and glucose, respectively. The linearity of method was found to be within the concentration range of 2000-10000 ng/spot for all above monosaccharides. The limit of detection for mannose, galactose, xylose and glucose was found to be 0.14986 ng/spot, 0.31973 ng/spot, 0.27569 ng/spot, and 0.36808 ng/spot, respectively. The limit of quantification for mannose, galactose, xylose and glucose was found to be 1.498 ng/spot, 3.197 ng/spot, 2.756 ng/spot, and 3.680 ng/spot, respectively. The method was also validated for precision, specificity and recovery. This developed method was used to analyze CP GM for monosaccharides compositions

  9. Relationship between molecular weight, monosaccharide composition and immunobiologic activity of Astragalus polysaccharides.

    Science.gov (United States)

    Jiang, Yiping; Qi, Xiaohui; Gao, Kai; Liu, Wenjun; Li, Na; Cheng, Ningbo; Ding, Gang; Huang, Wenzhe; Wang, Zhenzhong; Xiao, Wei

    2016-10-01

    Four Astragalus polysaccharides (APS1-APS4) were isolated from the water extract of Radix Astragali and purified through ethanol precipitation with 20 %, 40 %, 60 % and 80 % ethanol, respectively. The total sugar content was measured by sulfuric acid-phenol method. Their molecular weight was determined using high performance gel permeation chromatography (HPGPC) and their monosaccharide composition was analyzed by reversed-phase high performance liquid chromatography (HPLC) after pre-column derivatization. Then the immunobiologic activity of APS was evaluated by the experiment of spleen lymphocytes proliferation in vitro. The data suggested that precipitation by different concentration of ethanol will obtain different molecular weight APS, the higher concentration of ethanol the smaller molecular weight for APS. The molecular weights of four APS were 257.7 kDa, 40.1 kDa, 15.3 kDa and 3.2 kDa. Monosaccharide composition analysis indicated that APS1 consisted of glucose only, and APS2 all consisted of arabinose. APS3 consisted of rhamnose, glucose, galactose and arabinose and APS4 consisted of galactose and arabinose, in a molar ratio of 1:10.76:6.55:12 and 3.02:1. The result of immunobiologic activity assay showed that both APS2 and APS3 can effectively stimulate normal spleen lymphocyte proliferation in vitro. Apart from this, the effect of APS2 also showed dose dependent tendency from 6.25 μg/mL to 800 μg/mL. The result of this research indicated that Astragalus polysaccharides, which consist of arabinose and their molecular weight between 15.2 kDa to 40.1 kDa, neither too high nor too low, had significant immune activity.

  10. Histochemical effects of γ radiation on soft fruit cell walls

    International Nuclear Information System (INIS)

    Foa, E.; Jona, R.; Vallania, R.

    1980-01-01

    Irradiation effects in peaches, tomatoes, cherries and grapes on the composition of cell wall polysaccharides were investigated by histochemical techniques. Cell wall polysaccharides, separated by a modified Jensen's method were pectins, hemicellulose, non-cellulosic polysaccharides and cellulose. The extinction values of Periodic Acid Schiff stained tissues was measured by microscopical photometry. Irradiation induced highly significant changes in polysaccharide composition of mesocarp cell walls; these changes were found to be a function of time of irradiation after harvest and of the species tested. A general influence on polysaccharide molecules was not found. Variations produced by irradiation are postulated to be an interference with a regulatory system rather than a breakdown of a functional molecule (metabolic enzyme or polysaccharide. (author)

  11. The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens

    DEFF Research Database (Denmark)

    Moller, Isabel Eva; de Fine Licht, Henrik Hjarvard; Harholt, Jesper

    2011-01-01

    communities of microbial and invertebrate symbionts have evolved associations with the dump material from leaf-cutting ant nests, to exploit decomposition niches that the ant garden-fungus does not utilize. Our approach thus provides detailed insight into the nutritional benefits and shortcomings associated......The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus......, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste...

  12. Creep behaviour of thin walled composite tubes

    International Nuclear Information System (INIS)

    Thiebaud, F.; Muzic, B.; Perreux, D.; Varchon, D.; Oytana, C.; Lebras, J.

    1993-01-01

    Fiber reinforced composites are more and more employed in high performance structure for nuclear power plant, mainly as water piping tubes. The increase of the use of composites is due to the advantages that they give : high stiffness, large ultimate strength, corrosion resistance. This last advantage is sought for the pieces in contact with water, and it's one of the reason why the composite can be preferred to metal. However the mechanical behaviour of composite is actually poorly known. The high anisotropy is the main difficulty to obtain a realistic model of behaviour. This problem implies that the safety factor used in the design of structure is often too large. In this article a general overview of the mechanical behaviour of tube made in glass epoxy material is proposed. We discuss especially the creep behaviour under biaxial loadings. The form of the proposed model presently allows predicting a nonlinearity of the behaviour and provides a good correlation with the experimental data of several tests not described in this paper. It accounts for the change of the Poisson ratio during creep and cyclic tests. However the complete identification requires long time testings and consequently the model must be corrected to take into account the damage which occurs in these cases

  13. Airborne sound insulation of new composite wall structures

    Directory of Open Access Journals (Sweden)

    Ivanova Yonka

    2018-01-01

    Full Text Available Protection against noise is one of the essential requirements of the European Construction Product directive. In buildings, airborne sound insulation is used to define the acoustical quality between rooms. In order to develop wall structures with optimal sound insulation, an understanding of the physical origins of sound transmission is necessary. To develop a kind of knowledge that is applicable to the improvement of real walls and room barriers is the motive behind this study. The purpose of the work is to study the sound insulation of new composite wall structure.

  14. Digestion of polysaccharides, protein and lipids by adult cockerels fed on diets containing a pectic cell-wall material from white lupin (Lupinus albus L.) cotyledon.

    Science.gov (United States)

    Carré, B; Leclercq, B

    1985-11-01

    1. The cell-wall material of white lupin (Lupinus albus L.) cotyledon is characterized by low contents of cellulose (47 g/kg) and lignin (17 g/kg) and a high content of pectic substances (710 g/kg). The digestion of lupin cell-wall material by adult cockerels was estimated using gas-liquid chromatographic analyses of alditol acetates derived from polysaccharide sugars. The analyses were performed in the destarched water-insoluble fractions of feed and excreta. Digestibility measurements were carried out using a 3 d balance period including a 2 d feeding period and a 24 h final starvation period. 2. In the first experiment, six animals were given a diet containing 510 g white lupin cotyledon flour/kg which was the only source of protein and cell walls in the diet. The apparent digestibility of cell-wall components was near zero. 3. In the second experiment, three diets were prepared by diluting a fibre-free basal diet (diet A) by a semi-purified cell-wall preparation introduced at two different levels: 100 g/kg (diet B) and 200 g/kg (diet C). The semi-purified cell walls were prepared from the white lupin cotyledon flour used in the first experiment. The true digestibilities of polysaccharides measured in birds given diets B and C were near zero. It is suggested that the measurement of the neutral-detergent fibre (NDF) content according to Van Soest & Wine (1967) is not a suitable procedure for estimating the undigestible fibre content in poultry nutrition as the cell-wall pectic substances are not included in the NDF measurement. 4. Addition of the semi-purified cell-wall preparation (Expt 2) resulted in a slight decrease in the apparent protein digestibility. This decrease might be explained by the addition of undigestible cell-wall protein. 5. Addition of the semi-purified cell-wall preparation (Expt 2) had no effect on the apparent lipid digestibility. 6. The metabolizable energy values of the basal diet fraction of diets B and C were calculated assuming that

  15. Diurnal thermal analysis of microencapsulated PCM-concrete composite walls

    International Nuclear Information System (INIS)

    Thiele, Alexander M.; Sant, Gaurav; Pilon, Laurent

    2015-01-01

    Highlights: • Transient heat conduction across microencapsulated PCM-concrete walls was simulated. • Equivalent homogeneous wall with effective thermal properties was rigorously derived. • Adding PCM to the wall increases daily energy savings and delays peak thermal load. • Energy savings is maximum when PCM melting temperature equals indoor temperature. • Energy savings are limited in extreme climates but time delay can be large. - Abstract: This paper examines the benefits of adding microencapsulated phase change material (PCM) to concrete used in building envelopes to reduce energy consumption and costs. First, it establishes that the time-dependent thermal behavior of microencapsulated PCM-concrete composite walls can be accurately predicted by an equivalent homogeneous wall with appropriate effective thermal properties. The results demonstrate that adding microencapsulated PCM to concrete resulted in a reduction and a time-shift in the maximum heat flux through the composite wall subjected to diurnal sinusoidal outdoor temperature and solar radiation heat flux. The effects of the PCM volume fraction, latent heat of fusion, phase change temperature and temperature window, and outdoor temperature were evaluated. Several design rules were established including (i) increasing the PCM volume fraction and/or enthalpy of phase change increased the energy flux reduction and the time delay, (ii) the energy flux reduction was maximized when the PCM phase change temperature was close to the desired indoor temperature, (iii) the optimum phase change temperature to maximize the time delay increased with increasing average outdoor temperature, (iv) in extremely hot or cold climates, the thermal load could be delayed even though the reduction in daily energy flux was small, and (v) the choice of phase change temperature window had little effect on the energy flux reduction and on the time delay. This analysis can serve as a framework to design PCM composite walls

  16. Gap size and wall lesion development next to composite

    NARCIS (Netherlands)

    Kuper, N.K.; Opdam, N.J.M.; Ruben, J.L.; de Soet, J.J.; Cenci, M.S.; Bronkhorst, E.M.; Huysmans, M.C.D.N.J.M.

    2014-01-01

    This in situ study investigated whether there is a relationship between gap size and wall lesion development in dentin next to 2 composite materials, and whether a clinically relevant threshold for the gap size could be established. For 21 days, 14 volunteers wore a modified occlusal splint

  17. Chemical Compositions and Macrophage Activation of Polysaccharides from Leon's Mane Culinary-Medicinal Mushroom Hericium erinaceus (Higher Basidiomycetes) in Different Maturation Stages.

    Science.gov (United States)

    Li, Qiao-Zhen; Wu, Di; Chen, Xia; Zhou, Shuai; Liu, Yanfang; Yang, Yan; Cui, Fengjie

    2015-01-01

    We studied the effect of the maturation stage on the chemical compositions and macrophage activation activity of polysaccharides from the culinary-medicinal mushroom Hericium erinaceus. Results showed that total polysaccharides increased, whereas protein content decreased with the maturation stage development of fruiting body. Nine polysaccharide fractions, 3 from each of the maturity stages IV (small fungal spine stage), V (mid-fungal spine stage) and VI (mature), were prepared using the gradient ethanol precipitation method. The polysaccharide fraction HP4A isolated from the maturating-stage (stage IV) fruiting body had a significant difference from the fractions HP5A (stage V) and HP6A (stage VI) in the molecular weight distribution and monosaccharide compositions. Immunostimulating tests revealed that the polysaccharide fraction HP6 isolated from the mature stage (stage VI) fruiting body presented higher macrophage activation activity. Our findings provided important information for the harvest and use of H. erinaceus with higher qualities and functional benefits.

  18. Impact of 4 Lactobacillus plantarum capsular polysaccharide clusters on surface glycan composition and host cell signaling

    NARCIS (Netherlands)

    Remus, D.M.; Kranenburg, van R.; Swam, van I.I.; Taverne, N.; Bongers, R.S.; Wels, M.; Wells, J.; Bron, P.A.; Kleerebezem, M.

    2012-01-01

    Background - Bacterial cell surface-associated polysaccharides are involved in the interactions of bacteria with their environment and play an important role in the communication between pathogenic bacteria and their host organisms. Cell surface polysaccharides of probiotic species are far less well

  19. Seismic Behaviour of Composite Steel Fibre Reinforced Concrete Shear Walls

    Science.gov (United States)

    Boita, Ioana-Emanuela; Dan, Daniel; Stoian, Valeriu

    2017-10-01

    In this paper is presented an experimental study conducted at the “Politehnica” University of Timisoara, Romania. This study provides results from a comprehensive experimental investigation on the behaviour of composite steel fibre reinforced concrete shear walls (CSFRCW) with partially or totally encased profiles. Two experimental composite steel fibre reinforced concrete walls (CSFRCW) and, as a reference specimen, a typical reinforced concrete shear wall (RCW), (without structural reinforcement), were fabricated and tested under constant vertical load and quasi-static reversed cyclic lateral loads, in displacement control. The tests were performed until failure. The tested specimens were designed as 1:3 scale steel-concrete composite elements, representing a three storeys and one bay element from the base of a lateral resisting system made by shear walls. Configuration/arrangement of steel profiles in cross section were varied within the specimens. The main objective of this research consisted in identifying innovative solutions for composite steel-concrete shear walls with enhanced performance, as steel fibre reinforced concrete which was used in order to replace traditional reinforced concrete. A first conclusion was that replacing traditional reinforcement with steel fibre changes the failure mode of the elements, as from a flexural mode, in case of element RCW, to a shear failure mode for CSFRCW. The maximum lateral force had almost similar values but test results indicated an improvement in cracking response, and a decrease in ductility. The addition of steel fibres in the concrete mixture can lead to an increase of the initial cracking force, and can change the sudden opening of a crack in a more stable process.

  20. Effect of chemicals on production, composition and antioxidant activity of polysaccharides of Inonotus obliquus.

    Science.gov (United States)

    Xu, Xiangqun; Quan, Lili; Shen, Mengwei

    2015-01-01

    Polysaccharides are important secondary metabolites from the medicinal mushroom Inonotus obliquus. Various fatty acids, surfactants and organic solvents as cell membrane-reorganizing chemicals were investigated for their stimulatory effects on the growth of fungal mycelium and production of exopolysaccharides (EPS) and endopolysaccharides (IPS) by submerged fermentation of I. obliquus. After evaluation of 14 chemicals, oleic acid, Tween 80, and TritonX-100 were chosen for optimization of addition concentration and addition time. Among the three chemicals, 0.1% (v/v) Tween 80 gave maximum production of mycelial biomass, EPS, IPS1, and IPS2 with a increase of 16.6, 81.6, 37.7 and 18.1%, respectively, when supplemented at the early growth phase (24h after inoculation). These EPS, IPS1, and IPS2 had significantly (pmonosaccharide compositions than those from the control. The simultaneously enhanced accumulation of bioactive EPS and IPS of cultured I. obliquus supplemented with Tween 80 was evident. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Structural and biochemical changes induced by pulsed electric field treatments on Cabernet Sauvignon grape berry skins: impact on cell wall total tannins and polysaccharides.

    Science.gov (United States)

    Cholet, Céline; Delsart, Cristèle; Petrel, Mélina; Gontier, Etienne; Grimi, Nabil; L'hyvernay, Annie; Ghidossi, Remy; Vorobiev, Eugène; Mietton-Peuchot, Martine; Gény, Laurence

    2014-04-02

    Pulsed electric field (PEF) treatment is an emerging technology that is arousing increasing interest in vinification processes for its ability to enhance polyphenol extraction performance. The aim of this study was to investigate the effects of PEF treatment on grape skin histocytological structures and on the organization of skin cell wall polysaccharides and tannins, which, until now, have been little investigated. This study relates to the effects of two PEF treatments on harvested Cabernet Sauvignon berries: PEF1 (medium strength (4 kV/cm); short duration (1 ms)) and PEF2 (low intensity (0.7 kV/cm); longer duration (200 ms)). Histocytological observations and the study of levels of polysaccharidic fractions and total amounts of tannins allowed differentiation between the two treatments. Whereas PEF1 had little effect on the polyphenol structure and pectic fraction, PEF2 profoundly modified the organization of skin cell walls. Depending on the PEF parameters, cell wall structure was differently affected, providing variable performance in terms of polyphenol extraction and wine quality.

  2. Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

    Science.gov (United States)

    Zenoni, Sara; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Sanson, Andrea; de Groot, Peter; Sordo, Sara; Citterio, Sandra; Monti, Francesca; Pezzotti, Mario

    2011-08-01

    • Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  3. Functional duality of the cell wall.

    Science.gov (United States)

    Latgé, Jean-Paul; Beauvais, Anne

    2014-08-01

    The polysaccharide cell wall is the extracellular armour of the fungal cell. Although essential in the protection of the fungal cell against aggressive external stresses, the biosynthesis of the polysaccharide core is poorly understood. For a long time it was considered that this cell wall skeleton was a fixed structure whose role was only to be sensed as non-self by the host and consequently trigger the defence response. It is now known that the cell wall polysaccharide composition and localization continuously change to adapt to their environment and that these modifications help the fungus to escape from the immune system. Moreover, cell wall polysaccharides could function as true virulence factors. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Inplane shear capacity of reinforced composite masonry block walls

    International Nuclear Information System (INIS)

    White, W.H.; Tseng, W.S.

    1981-01-01

    The objective of this paper is to describe a test program performed to determine the inplane shear capacity, stiffness and ductility of composite masonry walls subjected to earthquake type loadings. Specimens were simultaneously subjected to a range of compressive loads to simulate dead load; and inplane shear loads with full load reversal to simulate the earthquake cycling load. The influence of horizontal and vertical reinforcing steel percentages on the inplane shear capacity, stiffness and ductility was also investigated. (orig./HP)

  5. Elastic torsional buckling of thin-walled composite cylinders

    Science.gov (United States)

    Marlowe, D. E.; Sushinsky, G. F.; Dexter, H. B.

    1974-01-01

    The elastic torsional buckling strength has been determined experimentally for thin-walled cylinders fabricated with glass/epoxy, boron/epoxy, and graphite/epoxy composite materials and composite-reinforced aluminum and titanium. Cylinders have been tested with several unidirectional-ply orientations and several cross-ply layups. Specimens were designed with diameter-to-thickness ratios of approximately 150 and 300 and in two lengths of 10 in. and 20 in. The results of these tests were compared with the buckling strengths predicted by the torsional buckling analysis of Chao.

  6. Cell wall composition and candidate biosynthesis gene expression during rice development

    DEFF Research Database (Denmark)

    Lin, Fan; Manisseri, Chithra; Fagerström, Alexandra

    2016-01-01

    Cell walls of grasses, including cereal crops and biofuel grasses, comprise the majority of plant biomass and intimately influence plant growth, development and physiology. However, the functions of many cell wall synthesis genes, and the relationships among and the functions of cell wall...... components remain obscure. To better understand the patterns of cell wall accumulation and identify genes that act in grass cell wall biosynthesis, we characterized 30 samples from aerial organs of rice (Oryza sativa cv. Kitaake) at 10 developmental time points, 3-100 d post-germination. Within these samples......, we measured 15 cell wall chemical components, enzymatic digestibility and 18 cell wall polysaccharide epitopes/ligands. We also used quantitative reverse transcription-PCR to measure expression of 50 glycosyltransferases, 15 acyltransferases and eight phenylpropanoid genes, many of which had...

  7. Single walled carbon nanotube composites for bone tissue engineering.

    Science.gov (United States)

    Gupta, Ashim; Woods, Mia D; Illingworth, Kenneth David; Niemeier, Ryan; Schafer, Isaac; Cady, Craig; Filip, Peter; El-Amin, Saadiq F

    2013-09-01

    The purpose of this study was to develop single walled carbon nanotubes (SWCNT) and poly lactic-co-glycolic acid (PLAGA) composites for orthopedic applications and to evaluate the interaction of human stem cells (hBMSCs) and osteoblasts (MC3T3-E1 cells) via cell growth, proliferation, gene expression, extracellular matrix production and mineralization. PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40, and 100 mg), characterized and degradation studies were performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Imaging studies revealed that MC3T3-E1 and hBMSCs cells exhibited normal, non-stressed morphology on the composites and all were biocompatible. Composites with 10 mg SWCNT resulted in highest rate of cell proliferation (p PLAGA composites imparted beneficial cellular growth capabilities and gene expression, and mineralization abilities were well established. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration and bone tissue engineering (BTE) and are promising for orthopedic applications. Copyright © 2013 Orthopaedic Research Society.

  8. Nonlinear analysis of composite thin-walled helicopter blades

    Science.gov (United States)

    Kalfon, J. P.; Rand, O.

    Nonlinear theoretical modeling of laminated thin-walled composite helicopter rotor blades is presented. The derivation is based on nonlinear geometry with a detailed treatment of the body loads in the axial direction which are induced by the rotation. While the in-plane warping is neglected, a three-dimensional generic out-of-plane warping distribution is included. The formulation may also handle varying thicknesses and mass distribution along the cross-sectional walls. The problem is solved by successive iterations in which a system of equations is constructed and solved for each cross-section. In this method, the differential equations in the spanwise directions are formulated and solved using a finite-differences scheme which allows simple adaptation of the spanwise discretization mesh during iterations.

  9. [The molecular composition and spectral properties of polysaccharide isolated from pu-erh tea and its material].

    Science.gov (United States)

    Gong, Jia-shun; Hu, Xiao-jing; Peng, Chun-xiu; Zhou, Hong-jie

    2010-07-01

    Pu-erh tea, a kind of well-known tea from the ancient time, is originally produced in the Yunnan Lanchan River basin through a special solid state fermentation by fungi. It uses sun-dried green tea as its starting materials. To investigate the variation of composition and spectral properties of polysaccharide during solid state fermentation of pu-erh tea by using Saccharomyces cerevisiae as preponderant starter and using sun-dried green tea as materials in the present study. The results showed that the content of water soluble polysaccharide was increased, and the activity of hydrolase such as cellulase, pectinase and glucomylase were also enhanced. The content of neutral sugar increased with the ferment time increasing and the M(w) of raw polysaccharide showed significant difference during fermentation. The main polysaccharide TPS2 and TPS1 were isolated and purified from pu-erh tea and its materials by DEAE-52 and Sephadex G-150 column chromatography. TPS2 contains the higher content of uronic acid, but TPS1 contains the higher contents of neutral sugar and protein. Monosaccharide analysis by GC-MS revealed that TPS1 and TPS2 were composed of arabinose, galactose, glucose, rhamnose, xylose and mannose with molar ratios of 24.2 : 23.6 : 5.9 : 3.2 : 1.8 : 1.1 and 19.3 : 26.9 : 3.2 : 2.7 : 1.3 : 5.5, respectively. The average molecular weight of TPS1 and TPS2 was 1.68 x 10(4) and 1.21 x 10(4) Daltons, respectively. UV scanning spectrum showed that TPS1 and TPS2 had no characteristic absorption between 200 and 400 nm wavelength, it suggested that they contain trace protein. IR spectrum of TPS1 and TPS2 demonstrated that pyranoid rings were contained in them. As shown in the image of atomic force microscope, the molecular appearance of TPS1 and TPS2 resembled islands and apparently consisted of conglomerations. The height of conglomerations of TPS2 was about 40 nm and the length or width was 0.5-0.8 microm, while the height of conglomerations of TPS1 was about 4nm and

  10. Effect of shear connectors on local buckling and composite action in steel concrete composite walls

    International Nuclear Information System (INIS)

    Zhang, Kai; Varma, Amit H.; Malushte, Sanjeev R.; Gallocher, Stewart

    2014-01-01

    Steel concrete composite (SC) walls are being used for the third generation nuclear power plants, and also being considered for small modular reactors. SC walls consist of thick concrete walls with exterior steel faceplates serving as reinforcement. These steel faceplates are anchored to the concrete infill using shear connectors, for example, headed steel studs. The steel faceplate thickness (t p ) and yield stress (F y ), and the shear connector spacing (s), stiffness (k s ), and strength (Q n ) determine: (a) the level of composite action between the steel plates and the concrete infill, (b) the development length of steel faceplates, and (c) the local buckling of the steel faceplates. Thus, the shear connectors have a significant influence on the behavior of composite SC walls, and should be designed accordingly. This paper presents the effects of shear connector design on the level of composite action and development length of steel faceplates in SC walls. The maximum steel plate slenderness, i.e., ratio of shear connector spacing-to-plate thickness (s/t p ) ratio to prevent local buckling before yielding is also developed based on the existing experimental database and additional numerical analysis

  11. Effect of shear connectors on local buckling and composite action in steel concrete composite walls

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai, E-mail: kai-zh@purdue.edu [School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Varma, Amit H., E-mail: ahvarma@purdue.edu [School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Malushte, Sanjeev R., E-mail: smalusht@bechtel.com [Bechtel Power Corporation, Frederick, MD (United States); Gallocher, Stewart, E-mail: stewart.gallocher@steelbricks.com [Modular Walling Systems Ltd., Glasgow (United Kingdom)

    2014-04-01

    Steel concrete composite (SC) walls are being used for the third generation nuclear power plants, and also being considered for small modular reactors. SC walls consist of thick concrete walls with exterior steel faceplates serving as reinforcement. These steel faceplates are anchored to the concrete infill using shear connectors, for example, headed steel studs. The steel faceplate thickness (t{sub p}) and yield stress (F{sub y}), and the shear connector spacing (s), stiffness (k{sub s}), and strength (Q{sub n}) determine: (a) the level of composite action between the steel plates and the concrete infill, (b) the development length of steel faceplates, and (c) the local buckling of the steel faceplates. Thus, the shear connectors have a significant influence on the behavior of composite SC walls, and should be designed accordingly. This paper presents the effects of shear connector design on the level of composite action and development length of steel faceplates in SC walls. The maximum steel plate slenderness, i.e., ratio of shear connector spacing-to-plate thickness (s/t{sub p}) ratio to prevent local buckling before yielding is also developed based on the existing experimental database and additional numerical analysis.

  12. Cell-wall polysaccharides play an important role in decay resistance of Sphagnum and actively depressed decomposition in vitro

    OpenAIRE

    Hajek, T.; Ballance, S.; Limpens, J.; Verhoeven, J.T.A.; Zijlstra, M.J.

    2011-01-01

    Sphagnum-dominated peatlands head the list of ecosystems with the largest known reservoirs of organic carbon (C). The bulk of this C is stored in decomposition-resistant litter of one bryophyte genus: Sphagnum. Understanding how Sphagnum litter chemistry controls C mineralization is essential for understanding potential interactions between environmental changes and C mineralization in peatlands. We aimed to separate the effects of phenolics from structural polysaccharides on decay of Sphagnu...

  13. Supercapacitance of Single-Walled Carbon Nanotubes-Polypyrrole Composites

    Directory of Open Access Journals (Sweden)

    Matei Raicopol

    2013-01-01

    Full Text Available The composites based on carbon nanotubes (CNTs and conducting polymers (CPs are promising materials for supercapacitor devices due to their unique nanostructure that combines the large pseudocapacitance of the CPs with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the CNTs. Here, we report a new electrochemical method to obtain polypyrrole (PPY/single-walled carbon nanotube (SWCNT composites. In the first step, the SWCNTs are covalently functionalized with monomeric units of pyrrole by esterification of acyl chloride functionalized SWCNTs and N-(6-hydroxyhexylpyrrole. In the second step, the PPY/SWCNTs composites are obtained by copolymerizing the pyrrole monomer with the pyrrole units grafted on SWCNTs surface using controlled potential electrolysis. The composites were further characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed good electrochemical charge storage properties for the synthesized composites based on PPY and SWCNTs covalently functionalized with pyrrole units making them promising electrode materials for high power supercapacitors.

  14. Fluorescent single walled nanotube/silica composite materials

    Science.gov (United States)

    Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

    2013-03-12

    Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

  15. Towards improved modeling of steel-concrete composite wall elements

    International Nuclear Information System (INIS)

    Vecchio, Frank J.; McQuade, Ian

    2011-01-01

    Highlights: → Improved analysis of double skinned steel concrete composite containment walls. → Smeared rotating crack concept applied in formulation of new analytical model. → Model implemented into finite element program; numerically stable and robust. → Models behavior of shear-critical elements with greater ease and improved accuracy. → Accurate assessments of strength, deformation and failure mode of test specimens. - Abstract: The Disturbed Stress Field Model, a smeared rotating crack model for reinforced concrete based on the Modified Compression Field Theory, is adapted to the analysis of double-skin steel-concrete wall elements. The computational model is then incorporated into a two-dimensional nonlinear finite element analysis algorithm. Verification studies are undertaken by modeling various test specimens, including panel elements subject to uniaxial compression, panel elements subjected to in-plane shear, and wall specimens subjected to reversed cyclic lateral displacements. In all cases, the analysis model is found to provide accurate calculations of structural load capacities, pre- and post-peak displacement responses, post-peak ductility, chronology of damage, and ultimate failure mode. Minor deficiencies are found in regards to the accurate portrayal of faceplate buckling and the effects of interfacial slip between the faceplates and the concrete. Other aspects of the modeling procedure that are in need of further research and development are also identified and discussed.

  16. The contribution of cell wall composition in the expansion of Camellia sinensis seedlings roots in response to aluminum.

    Science.gov (United States)

    Safari, Masoumeh; Ghanati, Faezeh; Safarnejad, Mohammad Reza; Chashmi, Najmeh Ahmadian

    2018-02-01

    Treatment with aluminum triggers a unique response in tea seedlings resulting in biochemical modification of the cell wall, regulation of the activity of the loosening agents, and elongation of root. Unlike most terrestrial plants, tea (Camellia sinensis L.) responds to aluminum (Al) through the promotion of its root elongation; but the real mechanism(s) behind this phenomenon is not well understood. A plausible relationship between the modifications of the cell wall and the promotion of root elongation was examined in tea seedlings treated for 8 days with 400 µM Al. The mechanical properties of the cell wall, the composition of its polysaccharides and their capacity to absorb Al, the expression of genes, and the activities of the wall-modifying proteins were studied. With 6 h of the treatment, about 40% of the absorbed Al was bound to the cell wall; however, the amount did not increase thereafter. Meanwhile, the activity of pectin methylesterase, the level of pectin demethylation, the amounts and the average molecular mass of xyloglucan in the root apices significantly decreased upon exposure to Al, resulting in the reduction of Al binding sites. On the other hand, the activity and the gene expression of peroxidase decreased, whereas the activity and gene expression of xyloglucan-degrading enzymes, the expression of expansin A and the H + -ATPase4 genes increased in the Al-treated plants. Interestingly, it was accompanied by the increase of elastic and viscous extensibility of the root apices. From the results, it can be suggested that the biochemical modification of the cell walls reduces sites of Al binding to roots and triggers the activity of the loosening agents, thereby increasing the length of tea roots.

  17. Effect of grape juice press fractioning on polysaccharide and oligosaccharide compositions of Pinot meunier and Chardonnay Champagne base wines.

    Science.gov (United States)

    Jégou, Sandrine; Hoang, Duc An; Salmon, Thomas; Williams, Pascale; Oluwa, Solomen; Vrigneau, Céline; Doco, Thierry; Marchal, Richard

    2017-10-01

    Press fractioning is an important step in the production of sparkling base wines to segregate the grape juices with different qualities. Grape juice fractions were collected during the pressing cycle at industrial and laboratory scales. The Pinot meunier and Chardonnay Champagne base wines obtained from the free-run juice and the squeezed juices exhibited strong differences from the beginning to the last step of pressing cycle for numerous enological parameters. Significant changes in polysaccharide (PS) and oligosaccharide (OS) base wine composition and concentration were found as the pressing cycle progressed. During the pressing cycle, the total PS concentration decreased by 31% (from 244 to 167mg/L) and 32% (from 201 to 136mg/L) in the Pinot meunier and Chardonnay wines respectively. The wine OS amounts varied between 97 and 139mg/L. The polysaccharide rich in arabinose and galactose (39-54%) and mannoproteins (38-55%) were the major PS in the base wines. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The comparative study on screening of pleurotus polysaccharide high-yield strains by use of ion beam implantation and composite mutagenesis

    International Nuclear Information System (INIS)

    Wang Lianfeng; Chen Henglei; Zhang Jun; Zeng Xianxian

    2009-01-01

    In order to screen pleurotus mycelium polysaccharide high-yield strains, the comparative study was made by use of ion beam implantation and composite mutagenesis before screening. The treating mycelium pellet of pleurotus ferulae tentatively with ion beam implantation was performed at the first. Two polysaccharide high-yield strains, PFPH-1and PFPH-2, were selected using fermentation quantitative screening after auxotrophy qualitative primary screening. It has been found that the polysaccharide yield of the mutants is 551.80mg/L and 659.46mg/L respectively,which increases by 46.55% and 75.14% respectively compared to that of initial strain. Then PFPH-1and PFPH-2, as the original strain, is exposed to ultraviolet light and is suffered by additive of LiCl respectively. The results indicate that the polysaccharide yield of strains 1,9 and 10 decreases by 27%, 38% and 37% respectively compared to that of PFPH-1 meanwhile the polysaccharide yield of strain 17 decreases by 28% compared to that of PFPH-2 after high-flux qualitative primary screening. In this study, composite mutagenesis with exposure of ultra-violet and additive of lithium chloride shows some negative effects. (authors)

  19. Local differentiation of cell wall matrix polysaccharides in sinuous pavement cells: its possible involvement in the flexibility of cell shape.

    Science.gov (United States)

    Sotiriou, P; Giannoutsou, E; Panteris, E; Galatis, B; Apostolakos, P

    2018-03-01

    The distribution of homogalacturonans (HGAs) displaying different degrees of esterification as well as of callose was examined in cell walls of mature pavement cells in two angiosperm and two fern species. We investigated whether local cell wall matrix differentiation may enable pavement cells to respond to mechanical tension forces by transiently altering their shape. HGA epitopes, identified with 2F4, JIM5 and JIM7 antibodies, and callose were immunolocalised in hand-made or semithin leaf sections. Callose was also stained with aniline blue. The structure of pavement cells was studied with light and transmission electron microscopy (TEM). In all species examined, pavement cells displayed wavy anticlinal cell walls, but the waviness pattern differed between angiosperms and ferns. The angiosperm pavement cells were tightly interconnected throughout their whole depth, while in ferns they were interconnected only close to the external periclinal cell wall and intercellular spaces were developed between them close to the mesophyll. Although the HGA epitopes examined were located along the whole cell wall surface, the 2F4- and JIM5- epitopes were especially localised at cell lobe tips. In fern pavement cells, the contact sites were impregnated with callose and JIM5-HGA epitopes. When tension forces were applied on leaf regions, the pavement cells elongated along the stretching axis, due to a decrease in waviness of anticlinal cell walls. After removal of tension forces, the original cell shape was resumed. The presented data support that HGA epitopes make the anticlinal pavement cell walls flexible, in order to reversibly alter their shape. Furthermore, callose seems to offer stability to cell contacts between pavement cells, as already suggested in photosynthetic mesophyll cells. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

  20. Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR

    Science.gov (United States)

    Romaniuk, Joseph A. H.; Cegelski, Lynette

    2015-01-01

    The ability to characterize bacterial cell-wall composition and structure is crucial to understanding the function of the bacterial cell wall, determining drug modes of action and developing new-generation therapeutics. Solid-state NMR has emerged as a powerful tool to quantify chemical composition and to map cell-wall architecture in bacteria and plants, even in the context of unperturbed intact whole cells. In this review, we discuss solid-state NMR approaches to define peptidoglycan composition and to characterize the modes of action of old and new antibiotics, focusing on examples in Staphylococcus aureus. We provide perspectives regarding the selected NMR strategies as we describe the exciting and still-developing cell-wall and whole-cell NMR toolkit. We also discuss specific discoveries regarding the modes of action of vancomycin analogues, including oritavancin, and briefly address the reconsideration of the killing action of β-lactam antibiotics. In such chemical genetics approaches, there is still much to be learned from perturbations enacted by cell-wall assembly inhibitors, and solid-state NMR approaches are poised to address questions of cell-wall composition and assembly in S. aureus and other organisms. PMID:26370936

  1. [Study on Monosaccharide Compositions of Polysaccharide in Dendrobium Stems of Different Resources by PMP-HPCE].

    Science.gov (United States)

    Chen, Nai-dong; Meng, Yun-fei; Yao, Hou-jun; Cao, Cai-yun; Chen, Chen; Li, Jun

    2015-08-01

    To establish a PMP-HPCE method for comparing the monosaccharides of polysaccharide in tissue-cultured and wild Dedrobium huoshanese and Dedrobium moniliforme as well as wild Dedrobium henanese, in order to investigate the similarities of their bioactive components. The PMP-monosaccharides of polysaccharide from the five investigated Dedrobium samples were separated by HPCE on a fused silica capillary column(100 cm x 50 µm) at 25 °C with 350 mmol/L BAS (adjusted to pH 10 with 1.0 mol/L NaOH) as running buffer for 34 min. The applied voltage was 20 kV and the detection wavelength was set at 250 nm. Total six monosaccharides including xylose, glucose, mannose, galactose, galacturonic acid and ribose were detected in the five Dendrobiurms samples and the similarity coefficients between the ten batches of the same Dendrobium species were all above 0. 98,while remarkable dissimilarity were exhibited among species and different resources. PMP-HPCE technique combined with chemometrics is simple, convenient, precise, reproducible and proved to be an effective strategy for identifying the species and origins, especially in the quality assessment of Dendrobium stems.

  2. MALDI-TOF MS and CE-LIF Fingerprinting of Plant Cell Wall Polysaccharide Digests as a Screening Tool for Arabidopsis Cell Wall Mutants

    NARCIS (Netherlands)

    Westphal, Y.; Schols, H.A.; Voragen, A.G.J.; Gruppen, H.

    2010-01-01

    Cell wall materials derived from leaves and hypocotyls of Arabidopsis mutant and wild type plants have been incubated with a mixture of pure and well-defined pectinases, hemicellulases, and cellulases. The resulting oligosaccharides have been subjected to MALDI-TOF MS and CE-LIF analysis. MALDI-TOF

  3. The Role of Pectin Acetylation in the Organization of Plant Cell Walls

    DEFF Research Database (Denmark)

    Fimognari, Lorenzo

    adopt defined 3D organization to allow their composition/interactions to be tweaked upon developmental need. Failure to build functional cell wall architecture will affect plant growth and resistance to stresses. In this PhD dissertation I explored the role of pectin acetylation in controlling...... wall organization, namely polysaccharides-to-polysaccharides interactions. These results suggest that cell wall acetylation is a mechanism that plants evolved to control cell wall organization. In Manuscript III, we report the characterization of Arabidopsis mutants trichome birefringence like (tbl) 10......All plant cells are surrounded by one or more cell wall layers. The cell wall serves as a stiff mechanical support while it allows cells to expand and provide a protective barrier to invading pathogens. Cell walls are dynamic structures composed of entangled cell wall polysaccharides that must...

  4. Composition and Antioxidant Activity of Water-Soluble Polysaccharides from Tuber indicum

    Science.gov (United States)

    Luo, Qiang; Zhang, Jie; Yan, Liang; Tang, Yuanlin; Ding, Xiang; Yang, Zhirong

    2011-01-01

    Abstract Crude water-soluble Chinese truffle Tuber indicum polysaccharide (TIP) was extracted from the fruiting bodies with water and then successively purified by DEAE–cellulose 52 and Sephadex G-100 column chromatography, yielding two major polysaccharide fractions: TIP1-1 and TIP2-1. High-performance gel permeation chromatography analysis showed that the average molecular sizes of TIP1-1 and TIP2-1 were approximately 1.75×104 Da and 5.73×103 Da, respectively. Monosaccharide component analysis by gas chromatography indicated that TIP1-1 was composed of mannose, glucose, galactose, and rhamannose in the respective molar ratio of 3.93:1.24:0.75:1.26 and that TIP2-1 contained mannose, glucose, and arabinose in the respective molar ratio of 5.27:1.44:0.43. The antioxidant activity analyses revealed that TIP1-1 and TIP2-1 possessed considerable antioxidant activity. Compared with TIP1-1, which has a higher molecular weight and contains no uronic acid, TIP2-1 exhibited a protective effect on PC12 cells injured by H2O2 and a higher scavenging activity against free radicals. The relative effects of the lower molecular size, the presence of uronic acid, and the antioxidant activity of TIP2-1 appear to be significant. Accordingly, the Chinese truffle T. indicum might serve as an effective antioxidative healthcare food and source of natural antioxidants. PMID:21877953

  5. Ultrasound enhances calcium absorption of jujube fruit by regulating the cellular calcium distribution and metabolism of cell wall polysaccharides.

    Science.gov (United States)

    Zhi, Huanhuan; Liu, Qiqi; Xu, Juan; Dong, Yu; Liu, Mengpei; Zong, Wei

    2017-12-01

    Ultrasound has been applied in fruit pre-washing processes. However, it is not sufficient to protect fruit from pathogenic infection throughout the entire storage period, and sometimes ultrasound causes tissue damage. The goal of this study was to investigate the effects of calcium chloride (CaCl 2 , 10 g L -1 ) and ultrasound (350 W at 40 kHz), separately and in combination, on jujube fruit quality, antioxidant status, tissue Ca 2+ content and distribution along with cell wall metabolism at 20 °C for 6 days. All three treatments significantly maintained fruit firmness and peel color, reduced respiration rate, decay incidence, superoxide anion, hydrogen peroxide and malondialdehyde and preserved higher enzymatic (superoxide dismutase, catalase and peroxidase) and non-enzymatic (ascorbic acid and glutathione) antioxidants compared with the control. Moreover, the combined treatment was more effective in increasing tissue Ca 2+ content and distribution, inhibiting the generation of water-soluble and CDTA-soluble pectin fractions, delaying the solubilization of Na 2 CO 3 -soluble pectin and having lower activities of cell wall-modifying enzymes (polygalacturonase and pectate lyase) during storage. These results demonstrated that the combination of CaCl 2 and ultrasound has potential commercial application to extend the shelf life of jujube fruit by facilitating Ca 2+ absorption and stabilizing the cell wall structure. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  6. Flow rates through earthen, geomembrane ampersand composite cut-off walls

    International Nuclear Information System (INIS)

    Tachavises, C.; Benson, C.H.

    1997-01-01

    Flow rates through soil-bentonite (SIB), geomembrane (GM), and composite geomembrane-soil (CGS) cut-off walls were determined using a numerical model of ground water flow. Various geological and wall conditions were simulated. Results of the simulations show that flow rates past all wall types are affected by hydraulic conductivities of the aquifer and underlying confining layer. Flow rates past GM walls with perfect joints are very low, provided the confining layer has low hydraulic conductivity. However, if a small fraction of the joints are defective, GM walls can be ineffective in blocking flow. CGS walls with a low hydraulic conductivity shell are less sensitive to joint defects. CGS walls with good shells typically have lower flow rates than SB and GM walls, even if the CGS wall contains defective joints

  7. Oocyst wall formation and composition in coccidian parasites

    Directory of Open Access Journals (Sweden)

    Kelly Mai

    2009-03-01

    Full Text Available The oocyst wall of coccidian parasites is a robust structure that is resistant to a variety of environmental and chemical insults. This resilience allows oocysts to survive for long periods, facilitating transmission from host to host. The wall is bilayered and is formed by the sequential release of the contents of two specialized organelles - wall forming body 1 and wall forming body 2 - found in the macrogametocyte stage of Coccidia. The oocyst wall is over 90% protein but few of these proteins have been studied. One group is cysteine-rich and may be presumed to crosslink via disulphide bridges, though this is yet to be investigated. Another group of wall proteins is rich in tyrosine. These proteins, which range in size from 8-31 kDa, are derived from larger precursors of 56 and 82 kDa found in the wall forming bodies. Proteases may catalyze processing of the precursors into tyrosine-rich peptides, which are then oxidatively crosslinked in a reaction catalyzed by peroxidases. In support of this hypothesis, the oocyst wall has high levels of dityrosine bonds. These dityrosine crosslinked proteins may provide a structural matrix for assembly of the oocyst wall and contribute to its resilience.

  8. Differences between easy- and difficult-to-mill chickpea (Cicer arietinum L.) genotypes. Part III: free sugar and non-starch polysaccharide composition.

    Science.gov (United States)

    Wood, Jennifer A; Knights, Edmund J; Campbell, Grant M; Choct, Mingan

    2014-05-01

    Parts I and II of this series of papers identified several associations between the ease of milling and the chemical compositions of different chickpea seed fractions. Non-starch polysaccharides were implicated; hence, this study examines the free sugars and sugar residues. Difficult milling is associated with: (1) lower glucose and xylose residues (less cellulose and xyloglucans) and more arabinose, rhamnose and uronic acid in the seed coat, suggesting a more flexible seed coat that resists cracking and decortication; (2) a higher content of soluble and insoluble non-starch polysaccharide fractions in the cotyledon periphery, supporting a pectic polysaccharide mechanism comprising arabinogalacturonan, homogalacturonan, rhamnogalalcturonan, and glucuronan backbone structures; (3) higher glucose and mannose residues in the cotyledon periphery, supporting a lectin-mediated mechanism of adhesion; and (4) higher arabinose and glucose residues in the cotyledon periphery, supporting a mechanism involving arabinogalactan-proteins. This series has shown that the chemical composition of chickpea does vary in ways that are consistent with physical explanations of how seed structure and properties relate to milling behaviour. Seed coat strength and flexibility, pectic polysaccharide binding, lectins and arabinogalactan-proteins have been implicated. Increased understanding in these mechanisms will allow breeding programmes to optimise milling performance in new cultivars. © 2013 Society of Chemical Industry.

  9. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2016-03-01

    Full Text Available The seismic performance of recycled aggregate concrete (RAC composite shear walls with different expandable polystyrene (EPS configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC protective layer (EPS modules as the external insulation layer, and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

  10. Role of the Group B antigen of Streptococcus agalactiae: a peptidoglycan-anchored polysaccharide involved in cell wall biogenesis.

    Directory of Open Access Journals (Sweden)

    Élise Caliot

    Full Text Available Streptococcus agalactiae (Group B streptococcus, GBS is a leading cause of infections in neonates and an emerging pathogen in adults. The Lancefield Group B carbohydrate (GBC is a peptidoglycan-anchored antigen that defines this species as a Group B Streptococcus. Despite earlier immunological and biochemical characterizations, the function of this abundant glycopolymer has never been addressed experimentally. Here, we inactivated the gene gbcO encoding a putative UDP-N-acetylglucosamine-1-phosphate:lipid phosphate transferase thought to catalyze the first step of GBC synthesis. Indeed, the gbcO mutant was unable to synthesize the GBC polymer, and displayed an important growth defect in vitro. Electron microscopy study of the GBC-depleted strain of S. agalactiae revealed a series of growth-related abnormalities: random placement of septa, defective cell division and separation processes, and aberrant cell morphology. Furthermore, vancomycin labeling and peptidoglycan structure analysis demonstrated that, in the absence of GBC, cells failed to initiate normal PG synthesis and cannot complete polymerization of the murein sacculus. Finally, the subcellular localization of the PG hydrolase PcsB, which has a critical role in cell division of streptococci, was altered in the gbcO mutant. Collectively, these findings show that GBC is an essential component of the cell wall of S. agalactiae whose function is reminiscent of that of conventional wall teichoic acids found in Staphylococcus aureus or Bacillus subtilis. Furthermore, our findings raise the possibility that GBC-like molecules play a major role in the growth of most if not all beta-hemolytic streptococci.

  11. Analyses of Aloe polysaccharides using carbohydrate microarray profiling

    DEFF Research Database (Denmark)

    Isager Ahl, Louise; Grace, Olwen M; Pedersen, Henriette Lodberg

    2018-01-01

    As the popularity of Aloe vera extracts continues to rise, a desire to fully understand the individual polymer components of the leaf mesophyll, their relation to one another and the effects they have on the human body are increasing. Polysaccharides present in the leaf mesophyll have been...... identified as the components responsible for the biological activities of Aloe vera, and they have been widely studied in the past decades. However, the commonly used methods do not provide the desired platform to conduct large comparative studies of polysaccharide compositions as most of them require...... a complete or near-complete fractionation of the polymers. The objective for this study was to assess whether carbohydrate microarrays could be used for the high-throughput analysis of cell wall polysaccharides in Aloe leaf mesophyll. The method we chose is known as Comprehensive Microarray Polymer Profiling...

  12. Alteration of cell wall polysaccharides through transgenic expression of UDP-Glc 4-epimerase-encoding genes in potato tubers.

    Science.gov (United States)

    Huang, Jie-Hong; Kortstee, Anne; Dees, Dianka C T; Trindade, Luisa M; Schols, Henk A; Gruppen, Harry

    2016-08-01

    Uridine diphosphate (UDP)-glucose 4-epimerase (UGE) catalyzes the conversion of UDP-glucose to UDP-galactose. Cell wall materials from the cv. Kardal (wild-type, background) and two UGE transgenic lines (UGE 45-1 and UGE 51-16) were isolated and fractionated. The galactose (Gal) content (mg/100g tuber) from UGE 45-1 transgenic line was 38% higher than that of wild-type, and resulted in longer pectin side chains. The Gal content present in UGE 51-16 was 17% lower than that of wild-type, although most pectin populations maintained the same level of Gal. Both UGE transgenic lines showed unexpectedly a decrease in acetylation and an increase in methyl-esterification of pectin. Both UGE transgenic lines showed similar proportions of homogalacturonan and rhamnogalacturonan I within pectin backbone as the wild-type, except for the calcium-bound pectin fraction exhibiting relatively less rhamnogalacturonan I. Next to pectin modification, xyloglucan populations from both transgenic lines were altered resulting in different XSGG and XXGG proportion in comparison to wild-type. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Study on Shear Performance of Cold-formed Steel Composite Wall with New Type of stud

    Science.gov (United States)

    Wang, Chungang; Yue, Sizhe; Liu, Hong; Zhang, Zhuangnan

    2018-03-01

    The shear resistance of single oriented-strand board wall and single gypsum board wall can be improved in different degrees by increasing strength of steel. The experimental data of literatures were used, and the test specimens had been simulated and validated by ABAQUS finite element analysis. According to the research, it showed that the compressive bearing capacity of the new stud composite wall was much better than the common stud composite wall, so the establishment and research of all models had been based on the new section stud. The analysis results show that when using new type of stud the shear resistance of the single oriented-strand board wall can be improved efficiently by increasing strength of steel, but the shear resistance of the single gypsum wall can be increased little.

  14. Cell Wall Composition, Biosynthesis and Remodeling during Pollen Tube Growth

    Directory of Open Access Journals (Sweden)

    Jean-Claude Mollet

    2013-03-01

    Full Text Available The pollen tube is a fast tip-growing cell carrying the two sperm cells to the ovule allowing the double fertilization process and seed setting. To succeed in this process, the spatial and temporal controls of pollen tube growth within the female organ are critical. It requires a massive cell wall deposition to promote fast pollen tube elongation and a tight control of the cell wall remodeling to modify the mechanical properties. In addition, during its journey, the pollen tube interacts with the pistil, which plays key roles in pollen tube nutrition, guidance and in the rejection of the self-incompatible pollen. This review focuses on our current knowledge in the biochemistry and localization of the main cell wall polymers including pectin, hemicellulose, cellulose and callose from several pollen tube species. Moreover, based on transcriptomic data and functional genomic studies, the possible enzymes involved in the cell wall remodeling during pollen tube growth and their impact on the cell wall mechanics are also described. Finally, mutant analyses have permitted to gain insight in the function of several genes involved in the pollen tube cell wall biosynthesis and their roles in pollen tube growth are further discussed.

  15. UV-radiation induced changes in antibiotic markers, chemical composition of water soluble polysaccharides and nodulation ability of Rhizobium trifolic 11B

    International Nuclear Information System (INIS)

    Ghai, Jyotsna; Ghai, S.K.; Kalra, M.S.

    1983-01-01

    Rhizobium trifolii 11B, which formed effective nodules on its host. Trifolium alexanderinum L. was UV-irradiated to isolate mutants. Out of the 9 variants isolated only 1 strain, viz. 21M11B produced more water soluble polysaccharide [752 mg (100 ml -1 )] than the parent 15 different antibiotics was similar only in two (22M11B and 26M11B) of the 9 UV-mutants. Compositional studies revealed that the water soluble polysaccharides from all strains contained glucose and galactose in the molar ratio of 7:1. Glucuronic acid which was present (2.33 per cent) in the water soluble polysaccharide from strain 11B was absent in all but 2UV-mutants (4.22per cent in 6M11B and 4.04per cent in26M11B). Five of the UB-mutants (1M11B, 17M11B, 20N11B, 22M11B and 26M11B) were Nod - . The organisms which produced more water soluble polysaccharide upon infection of the plants induced the formation of more number of nodules. (author)

  16. Electrophoretic deposition of organic/inorganic composite coatings on metallic substrates for bone replacement applications: mechanisms and development of new bioactive materials based on polysaccharides

    OpenAIRE

    Cordero Arias, Luis Eduardo

    2015-01-01

    Regarding the need to improve the usually encountered osteointegration of metallic implants with the surrounding body tissue in bone replacement applications, bioactive organic/inorganic composite coatings on metallic substrates were developed in this work using electrophoretic deposition (EPD) as coating technology. In the present work three polysaccharides, namely alginate, chondroitin sulfate and chitosan were used as the organic part, acting as the matrix of the coating and enabling the c...

  17. Soluble polysaccharide composition and myo-inositol content help differentiate the antioxidative and hypolipidemic capacity of peeled apples.

    Science.gov (United States)

    Ker, Yaw-Bee; Peng, Chiung-Huei; Chyau, Charng-Cherng; Peng, Robert Y

    2010-04-28

    Many people prefer to eat peeled apples. The present study investigated the composition of soluble polysaccharides (SP) in peeled apples and its antioxidative and hypolipidemic activity. The yield of SP ranged 0.43-0.88%, having MW ranging 223-848 kDa. All belonged to peptidoglycans. Among the fourteen amino acids found, seven were essential amino acids. In addition, sugar analysis indicated that 50% of apple samples consisted of glucoarabinan, 37.5% comprising taloarabinan and the remaining 12.5% containing alloglucan. Moreover, SP consisted of a huge amount of myo-inositol (>5.61%) and uronic acid (>11.7%), which may play a synergistic role in the hypolipidemic effect. Worth noting, we are the first who reported the presence of talose, allose and fucose in the apple SP. Conclusively, the biological value of SP is attributable to the differential effect of SP and the synergistic effect exerted by its unique SP pattern, high myo-inositol and uronic acid contents.

  18. Strengthening of Unreinforced Masonry Walls with Composite Materials

    Directory of Open Access Journals (Sweden)

    Ioana-Sorina Enţuc

    2004-01-01

    Full Text Available Unreinforced masonry (URM is considered one of the oldest construction materials being until the end of XIXth century, the basic material for: foundations, walls, columns, volts, staircases, floor joints, roofs, retaining walls, drainage channels, barrages, etc. Construction with URM elements posses a series of advantages such as: fire resistance, thermal an acoustic insulations between interior and outside spaces, humidity resistance. However the URM elements have some significant inconveniences such as: large self weight (heaviness causes cracks in the other elements of structures, reduced mechanical strengths in comparison with other traditional materials (steel and concrete, low tenacity, great manual labor consumptions, and vulnerability to earthquakes. Various factors cause deteriorations which must be overcome by strengthening solutions. Some strengthening solutions based on fiber reinforced polymers (FRP products applied directly on URM brick walls are presented in the paper.

  19. The composition and metabolism of faecal microbiota is specifically modulated by different dietary polysaccharides and mucin: an isothermal microcalorimetry study.

    Science.gov (United States)

    Adamberg, K; Kolk, K; Jaagura, M; Vilu, R; Adamberg, S

    2018-01-29

    The metabolic activity of colon microbiota is specifically affected by fibres with various monomer compositions, degree of polymerisation and branching. The supply of a variety of dietary fibres assures the diversity of gut microbial communities considered important for the well-being of the host. The aim of this study was to compare the impact of different oligo- and polysaccharides (galacto- and fructooligosaccharides, resistant starch, levan, inulin, arabinogalactan, xylan, pectin and chitin), and a glycoprotein mucin on the growth and metabolism of faecal microbiota in vitro by using isothermal microcalorimetry (IMC). Faecal samples from healthy donors were incubated in a phosphate-buffered defined medium with or without supplementation of a single substrate. The generation of heat was followed on-line, microbiota composition (V3-V4 region of the 16S rRNA using Illumina MiSeq v2) and concentrations of metabolites (HPLC) were determined at the end of growth. The multiauxic power-time curves obtained were substrate-specific. More than 70% of all substrates except chitin were fermented by faecal microbiota with total heat generation of up to 8 J/ml. The final metabolite patterns were in accordance with the microbiota changes. For arabinogalactan, xylan and levan, the fibre-affected distribution of bacterial taxa showed clear similarities (e.g. increase of Bacteroides ovatus and decrease of Bifidobacterium adolescentis). The formation of propionic acid, an important colon metabolite, was enhanced by arabinogalactan, xylan and mucin but not by galacto- and fructooligosaccharides or inulin. Mucin fermentation resulted in acetate, propionate and butyrate production in ratios previously observed for faecal samples, indicating that mucins may serve as major substrates for colon microbial population. IMC combined with analytical methods was shown to be an effective method for screening the impact of specific dietary fibres on functional changes in faecal microbiota.

  20. Compressive behavior of energy-saving fired facing brick composite wall

    Science.gov (United States)

    Guo, Kai; Wu, Cai

    2018-03-01

    The energy-saving fired facing brick composite wall has a broad development prospects due to its merits of thermal insulation, energy conservation, beautiful, and natural. The construction and characteristics of this wall are introduced and analyzed in this paper. Experimental studies of samples are also conducted to investigate its compressive performance. The results show that the energy-saving fired facing brick composite wall has high compressive capacity. It has considerable application prospect, the study in this paper provides foundation to further studies.

  1. Suppression of CCR impacts metabolite profile and cell wall composition in Pinus radiata tracheary elements.

    Science.gov (United States)

    Wagner, Armin; Tobimatsu, Yuki; Goeminne, Geert; Phillips, Lorelle; Flint, Heather; Steward, Diane; Torr, Kirk; Donaldson, Lloyd; Boerjan, Wout; Ralph, John

    2013-01-01

    Suppression of the lignin-related gene cinnamoyl-CoA reductase (CCR) in the Pinus radiata tracheary element (TE) system impacted both the metabolite profile and the cell wall matrix in CCR-RNAi lines. UPLC-MS/MS-based metabolite profiling identified elevated levels of p-coumaroyl hexose, caffeic acid hexoside and ferulic acid hexoside in CCR-RNAi lines, indicating a redirection of metabolite flow within phenylpropanoid metabolism. Dilignols derived from coniferyl alcohol such as G(8-5)G, G(8-O-4)G and isodihydrodehydrodiconiferyl alcohol (IDDDC) were substantially depleted, providing evidence for CCR's involvement in coniferyl alcohol biosynthesis. Severe CCR suppression almost halved lignin content in TEs based on a depletion of both H-type and G-type lignin, providing evidence for CCR's involvement in the biosynthesis of both lignin types. 2D-NMR studies revealed minor changes in the H:G-ratio and consequently a largely unchanged interunit linkage distribution in the lignin polymer. However, unusual cell wall components including ferulate and unsaturated fatty acids were identified in TEs by thioacidolysis, pyrolysis-GC/MS and/or 2D-NMR in CCR-RNAi lines, providing new insights into the consequences of CCR suppression in pine. Interestingly, CCR suppression substantially promoted pyrolytic breakdown of cell wall polysaccharides, a phenotype most likely caused by the incorporation of acidic compounds into the cell wall matrix in CCR-RNAi lines.

  2. Effect of nutrient calcium on the cell wall composition and ...

    African Journals Online (AJOL)

    The effect of calcium in the nutrient medium on kikuyu grass (Pennisetum clandestinum Hochst), grown in a solution culture, was investigated. Calcium had no effect on the lignin content of leaf material, but decreased the lignin content per unit stem cell wall. Calcium appeared to have no significant effect on either the ...

  3. Genome-Wide Association Mapping for Cell Wall Composition and Properties in Temperate Grasses

    DEFF Research Database (Denmark)

    Bellucci, Andrea

    with a wide range of chemical bounds. At present the interest in plant cell wall is growing due to the possibility to convert ligno-cellulosic biomass (e.g. agricultural residues) into bioethanol but also for the benefits to human health of some cell wall constituents found in cereals, in particular beta......-glucans. Plant cell wall biosynthesis is regulated by a large number of genes and regulatory factors but very few of these are known and characterized. This PhD project aimed to the identification of putative candidate genes involved in plant cell wall composition and properties using a genome wide (GWAS......) approach. The species investigate were wheat, barley and B. distachyon, considered a model plant for temperate cereals. Agronomical traits as yield and plant height were also included in the analysis along with cell wall composition and saccharification properties. Several marker-trait associations were...

  4. Utilization of poor quality roughages III. Effect of gamma irradiation on chemical composition and structural polysaccharides utilization of straws

    International Nuclear Information System (INIS)

    Rai, S.N.; Mudgal, V.D.

    1985-01-01

    The wheat and paddy straws were irradiated with 60 Co gamma source in doses of 10 5 and 10 6 rad, respectively. The data indicated that these doses applied to straws were not sufficient to bring the appreciable changes in the chemical composition in wheat straw. However, the cell wall constituents, acid detergent fiber, hemicellulose, cellulose, lignin : cellulose ratio and acid insoluble ash decreased (P < 0.05), while cell contents increased (P < 0.01) in irradiated samples of paddy straw. The findings further revealed that small changes in chemical composition due to irradiation could not bring any significant changes in the in vitro digestibility values for any of the fibre components in both the straws, except in paddy straw, where the in vitro acid detergent fibre digestibility was reduced (P < 0.05), while availability index increased (P < 0.05) due to irradiation. (author)

  5. Isolation of the Cell Wall.

    Science.gov (United States)

    Canut, Hervé; Albenne, Cécile; Jamet, Elisabeth

    2017-01-01

    This chapter describes a method allowing the purification of the cell wall for studying both polysaccharides and proteins. The plant primary cell wall is mainly composed of polysaccharides (90-95 % in mass) and of proteins (5-10 %). At the end of growth, specialized cells may synthesize a lignified secondary wall composed of polysaccharides (about 65 %) and lignin (about 35 %). Due to its composition, the cell wall is the cellular compartment having the highest density and this property is used for its purification. It plays critical roles during plant development and in response to environmental constraints. It is largely used in the food and textile industries as well as for the production of bioenergy. All these characteristics and uses explain why its study as a true cell compartment is of high interest. The proposed method of purification can be used for large amount of material but can also be downscaled to 500 mg of fresh material. Tools for checking the quality of the cell wall preparation, such as protein analysis and microscopy observation, are also provided.

  6. Macroporous silica–alumina composites with mesoporous walls

    Indian Academy of Sciences (India)

    Macroporous silica–alumina composites with mesopores have been prepared by employing polymethylmethacrylate beads as templates in the presence of the cationic surfactant, N-cetyl-N,N,N-trimethylammonium bromide. The Si/Al ratio in the composites has been varied between 4.5 and 48 and the occurrence of ...

  7. Inactivation of the Ecs ABC transporter of Staphylococcus aureus attenuates virulence by altering composition and function of bacterial wall.

    Directory of Open Access Journals (Sweden)

    Ing-Marie Jonsson

    2010-12-01

    Full Text Available Ecs is an ATP-binding cassette (ABC transporter present in aerobic and facultative anaerobic gram-positive Firmicutes. Inactivation of Bacillus subtilis Ecs causes pleiotropic changes in the bacterial phenotype including inhibition of intramembrane proteolysis. The molecule(s transported by Ecs is (are still unknown.In this study we mutated the ecsAB operon in two Staphylococcus aureus strains, Newman and LS-1. Phenotypic and functional characterization of these Ecs deficient mutants revealed a defect in growth, increased autolysis and lysostaphin sensitivity, altered composition of cell wall proteins including the precursor form of staphylokinase and an altered bacterial surface texture. DNA microarray analysis indicated that the Ecs deficiency changed expression of the virulence factor regulator protein Rot accompanied by differential expression of membrane transport proteins, particularly ABC transporters and phosphate-specific transport systems, protein A, adhesins and capsular polysaccharide biosynthesis proteins. Virulence of the ecs mutants was studied in a mouse model of hematogenous S. aureus infection. Mice inoculated with the ecs mutant strains developed markedly milder infections than those inoculated with the wild-type strains and had consequently lower mortality, less weight loss, milder arthritis and decreased persistence of staphylococci in the kidneys. The ecs mutants had higher susceptibility to ribosomal antibiotics and plant alkaloids chelerythrine and sanguinarine.Our results show that Ecs is essential for staphylococcal virulence and antimicrobial resistance probably since the transport function of Ecs is essential for the normal structure and function of the cell wall. Thus targeting Ecs may be a new approach in combating staphylococcal infection.

  8. Inactivation of the Ecs ABC transporter of Staphylococcus aureus attenuates virulence by altering composition and function of bacterial wall.

    Science.gov (United States)

    Jonsson, Ing-Marie; Juuti, Jarmo T; François, Patrice; AlMajidi, Rana; Pietiäinen, Milla; Girard, Myriam; Lindholm, Catharina; Saller, Manfred J; Driessen, Arnold J M; Kuusela, Pentti; Bokarewa, Maria; Schrenzel, Jacques; Kontinen, Vesa P

    2010-12-02

    Ecs is an ATP-binding cassette (ABC) transporter present in aerobic and facultative anaerobic gram-positive Firmicutes. Inactivation of Bacillus subtilis Ecs causes pleiotropic changes in the bacterial phenotype including inhibition of intramembrane proteolysis. The molecule(s) transported by Ecs is (are) still unknown. In this study we mutated the ecsAB operon in two Staphylococcus aureus strains, Newman and LS-1. Phenotypic and functional characterization of these Ecs deficient mutants revealed a defect in growth, increased autolysis and lysostaphin sensitivity, altered composition of cell wall proteins including the precursor form of staphylokinase and an altered bacterial surface texture. DNA microarray analysis indicated that the Ecs deficiency changed expression of the virulence factor regulator protein Rot accompanied by differential expression of membrane transport proteins, particularly ABC transporters and phosphate-specific transport systems, protein A, adhesins and capsular polysaccharide biosynthesis proteins. Virulence of the ecs mutants was studied in a mouse model of hematogenous S. aureus infection. Mice inoculated with the ecs mutant strains developed markedly milder infections than those inoculated with the wild-type strains and had consequently lower mortality, less weight loss, milder arthritis and decreased persistence of staphylococci in the kidneys. The ecs mutants had higher susceptibility to ribosomal antibiotics and plant alkaloids chelerythrine and sanguinarine. Our results show that Ecs is essential for staphylococcal virulence and antimicrobial resistance probably since the transport function of Ecs is essential for the normal structure and function of the cell wall. Thus targeting Ecs may be a new approach in combating staphylococcal infection.

  9. Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Zhang, Jianwei; Xu, Fangfang

    2013-12-01

    A composite shear wall concept based on concrete filled steel tube (CFST) columns and steel plate (SP) deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements: CFST columns; SP deep beams; and reinforced concrete (RC) strips. The RC strips are intended to allow the core structural elements — the CFST columns and SP deep beams — to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

  10. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

    2017-04-01

    Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

  11. Carbohydrate composition and in vitro digestibility of dry matter and non-starch polysaccharides in corn, sorghum, and wheat, and co-products from these grains

    DEFF Research Database (Denmark)

    Jaworski, N. A.; Lærke, Helle Nygaard; Knudsen, Knud Erik Bach

    2015-01-01

    The objectives of this work were to determine carbohydrate composition and in vitro digestibility of DM and nonstarch polysaccharides (NSP) in corn, wheat, and sorghum and coproducts from these grains. In the initial part of this work, the carbohydrate composition of 12 feed ingredients was deter......The objectives of this work were to determine carbohydrate composition and in vitro digestibility of DM and nonstarch polysaccharides (NSP) in corn, wheat, and sorghum and coproducts from these grains. In the initial part of this work, the carbohydrate composition of 12 feed ingredients...... was determined. The 12 ingredients included 3 grains (corn, sorghum, and wheat), 3 coproducts from the dry grind industry (corn distillers dried grains with solubles [DDGS] and 2 sources of sorghum DDGS), 4 coproducts from the wet milling industry (corn gluten meal, corn gluten feed, corn germ meal, and corn...... up approximately 22, 49, and 29% (DM basis), respectively, of the NSP in corn and corn coproducts and approximately 25, 43, and 32% (DM basis), respectively, of the NSP in sorghum and sorghum DDGS. Cellulose, arabinoxylans, and other hemicelluloses made up approximately 16, 64, and 20% (DM basis...

  12. Influence of grape maturity and maceration length on color, polyphenolic composition, and polysaccharide content of Cabernet Sauvignon and Tempranillo wines.

    Science.gov (United States)

    Gil, Mariona; Kontoudakis, Nikolaos; González, Elena; Esteruelas, Mireia; Fort, Francesca; Canals, Joan Miquel; Zamora, Fernando

    2012-08-15

    The aim of this paper was to study how maturity and maceration length affect color, phenolic compounds, polysaccharides, and sensorial quality of Cabernet Sauvignon and Tempranillo wines at three stages of grape ripening. Ripeness increased color extractability, phenolic compounds, and polysaccharide concentrations. Moreover, the proanthocyanidin mean degree of polymerization (mDP) and the percentage of prodelphinidins also increased with maturity, whereas the percentage of galloylation decreased. In general, wines from riper grapes contain higher proportions of skin proanthocyanidins. Color and anthocyanin concentration decreased when the maceration was longer, whereas polysaccharide and proanthocyanidin concentrations did the opposite. It was also detected that the mDP and the percentage of prodelphinidins decreased when the maceration was extended, whereas the percentage of galloylation increased. These data seem to indicate that proanthocyanidin extraction from seeds is clearly increased throughout the maceration time.

  13. Regulation and diversity of plant polysaccharide utilisation in fungi

    NARCIS (Netherlands)

    Battaglia, E.

    2011-01-01

    Filamentous fungi obtain their nutrients by degrading dead or living plant material. Plant material consists of different cell wall and storage polysaccharides. Due to the complex structure and the variety of plant polysaccharides, filamentous fungi secrete a wide range of plant polysaccharide

  14. Direct displacement-based design of special composite RC shear walls with steel boundary elements

    Directory of Open Access Journals (Sweden)

    H. Kazemi

    2016-06-01

    Full Text Available Special composite RC shear wall (CRCSW with steel boundary elements is a kind of lateral force resisting structural system which is used in earthquake-prone regions. Due to their high ductility and energy dissipation, CRCSWs have been widely used in recent years by structural engineers. However, there are few studies in the literature on the seismic design of such walls. Although there are many studies in the literature on the Direct Displacement-Based Design (DDBD of RC structures, however, no study can be found on DDBD of CRCSWs. Therefore, the aim of present study is to evaluate the ability of DDBD method for designing CRCSWs. In this study, four special composite reinforced concrete shear walls with steel boundary elements of 4, 8, 12 and 16 story numbers were designed using the DDBD method for target drift of 2%. The seismic behavior of the four CRCSWs was studied using nonlinear time-history dynamic analyses. Dynamic analyses were performed for the mentioned walls using 7 selected earthquake records. The seismic design parameters considered in this study includes: lateral displacement profile, inelastic dynamic inter-story drift demand, failure pattern and the composite RC shear walls overstrength factor. For each shear wall, the overall overstrength factor was calculated by dividing the ultimate dynamic base shear demand (Vu by the base shear demand (Vd as per the Direct Displacement Based-Design (DDBD method. The results show that the DDBD method can be used to design CRCSWs safely in seismic regions with predicted behavior.

  15. Characterization of Cell Wall Components and Their Modifications during Postharvest Storage of Asparagus officinalis L.: Storage-Related Changes in Dietary Fiber Composition.

    Science.gov (United States)

    Schäfer, Judith; Wagner, Steffen; Trierweiler, Bernhard; Bunzel, Mirko

    2016-01-20

    Changes in cell wall composition during storage of plant foods potentially alter the physiological effects of dietary fiber components. To investigate postharvest cell wall modifications of asparagus and their consequences in terms of insoluble dietary fiber structures, asparagus was stored at 20 and 1 °C for different periods of time. Structural analyses demonstrated postharvest changes in the polysaccharide profile, dominated by decreased portions of galactans. Increasing lignin contents correlated with compositional changes (monolignol ratios and linkage types) of the lignin polymer as demonstrated by chemical and two-dimensional nuclear magnetic resonance (2D-NMR) methods. Depending on the storage time and temperature, syringyl units were preferentially incorporated into the lignin polymer. Furthermore, a drastic increase in the level of ester-linked phenolic monomers (i.e., p-coumaric acid and ferulic acid) and polymer cross-links (di- and triferulic acids) was detected. The attachment of p-coumaric acid to lignin was demonstrated by 2D-NMR experiments. Potential consequences of postharvest modifications on physiological effects of asparagus dietary fiber are discussed.

  16. Analysis of the monosaccharide composition of water-soluble polysaccharides from Sargassum fusiforme by high performance liquid chromatography/electrospray ionisation mass spectrometry.

    Science.gov (United States)

    Wu, Xiaodan; Jiang, Wei; Lu, Jiajia; Yu, Ying; Wu, Bin

    2014-02-15

    Sargassum fusiforme (hijiki) is the well-known edible algae, whose polysaccharides have been proved to possess interesting bioactivities like antitumor, antioxidant, antimicrobial and immunomodulatory activities. A facile and sensitive method based on high-performance liquid chromatography method of pre-column derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) coupled with electrospray ionisation mass spectrometry (HPLC/ESI-MS) has been established for the analysis of the monosaccharide composition of polysaccharides in S. fusiforme. Monosaccharides have been converted into PMP-labelled derivatives with aqueous ammonia as a catalyst at 70 °C for 30 min. The optimisation of the pre-column derivatization process was studied. The LODs of the monosaccharides were in the range from 0.01 to 0.02 nmol. PMP-labelled mixture of monosaccharides has been well separated by a reverse-phase HPLC and detected by on-line ESI-MS method under optimised conditions. The mobile phase of elution system was chosen as acetonitrile (solvent A) and 20mM aqueous ammonium acetate (solvent B) (pH 3.0) with Zorbax XDB-C18 column at 30 °C for the separation of the monosaccharide derivatives. Identification of the monosaccharides composition was carried out by analysis with mass spectral behaviour and chromatography characteristics of 1-phenyl-3-methyl-5-pyrazolone (PMP) labelled monosaccharides. All PMP-labelled derivatives display high chemical stabilities, whose regular MS fragmentation is specific for reducing labelled sugars. The result showed that the S. fusiforme polysaccharide consisted of mannose, glucose, galactose, xylose, fucose and glucuronic acid or galacturonic acid, or both uronic acids. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Directory of Open Access Journals (Sweden)

    Ying Luo

    Full Text Available The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  18. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Science.gov (United States)

    Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

    2015-01-01

    The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  19. The composition of cell walls from grape skin in Vitis vinifera intraspecific hybrids.

    Science.gov (United States)

    Apolinar-Valiente, Rafael; Gómez-Plaza, Encarna; Terrier, Nancy; Doco, Thierry; Ros-García, José María

    2017-09-01

    Monastrell is a red grape cultivar adapted to the dry environmental conditions of Murcia, SE Spain. Its berries seem to be characterized by a rigid cell wall structure, which could make difficult the winemaking process. Cabernet Sauvignon cultivar is used to complement Monastrell wines in this region owing to its high phenolic content with high extractability. This study explores the skin cell wall composition of grapes from plants resulting from intraspecific crosses of Vitis vinifera cultivars Monastrell × Cabernet Sauvignon. Moreover, the morphology of the cell wall material (CWM) from some representative samples was visualized by transmission optical microscopy. The total sugar content of CWM from nine out of ten genotypes of the progeny was lower than that from Monastrell. Seven out of ten genotypes showed lower phenolic content than Cabernet Sauvignon. The CWM from nine out of ten hybrids presented lower protein content than that from Monastrell. This study confirms that skin cell walls from Monastrell × Cabernet Sauvignon hybrid grapes presented major differences in composition compared with their parents. These data could help in the development of new cultivars adapted to the dry conditions of SE Spain and with a cell wall composition favouring extractability. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  20. Bayesian decision and mixture models for AE monitoring of steel-concrete composite shear walls

    Science.gov (United States)

    Farhidzadeh, Alireza; Epackachi, Siamak; Salamone, Salvatore; Whittaker, Andrew S.

    2015-11-01

    This paper presents an approach based on an acoustic emission technique for the health monitoring of steel-concrete (SC) composite shear walls. SC composite walls consist of plain (unreinforced) concrete sandwiched between steel faceplates. Although the use of SC system construction has been studied extensively for nearly 20 years, little-to-no attention has been devoted to the development of structural health monitoring techniques for the inspection of damage of the concrete behind the steel plates. In this work an unsupervised pattern recognition algorithm based on probability theory is proposed to assess the soundness of the concrete infill, and eventually provide a diagnosis of the SC wall’s health. The approach is validated through an experimental study on a large-scale SC shear wall subjected to a displacement controlled reversed cyclic loading.

  1. Stability of cell wall composition and saccharification efficiency in Miscanthus across diverse environments

    NARCIS (Netherlands)

    Weijde, van der Tim; Dolstra, Oene; Visser, Richard G.F.; Trindade, Luisa M.

    2017-01-01

    To investigate the potential effects of differences between growth locations on the cell wall composition and saccharification efficiency of the bioenergy crop miscanthus, a diverse set of 15 accessions were evaluated in six locations across Europe for the first 3 years following establishment.

  2. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    NARCIS (Netherlands)

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De

    2006-01-01

    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  3. Cell wall composition throughout development for the model grass Brachypodium distanchyon

    Directory of Open Access Journals (Sweden)

    David eRancour

    2012-12-01

    Full Text Available Temperate perennial grasses are important worldwide as a livestock nutritive energy source and a potential feedstock for lignocellulosic biofuel production. The annual temperate grass Brachypodium distanchyon has been championed as a useful model system to facilitate biological research in agriculturally important temperate forage grasses based on phylogenetic relationships. To physically corroborate genetic predictions, we determined the chemical composition profiles of organ-specific cell walls throughout the development of two common diploid accessions of Brachypodium distanchyon, Bd21-3 and Bd21. Chemical analysis was performed on cell walls isolated from distinct organs (i.e. leaves, sheaths, stems and roots at three developmental stages of 1 12-day seedling, 2 vegetative-to-reproductive transition, and 3 mature seed-fill. In addition, we have included cell wall analysis of embryonic callus used for genetic transformations. Composition of cell walls based on components lignin, hydroxycinnamates, uronosyls, neutral sugars, and protein suggests that Brachypodium distanchyon is similar chemically to agriculturally important forage grasses. There were modest compositional differences in hydroxycinnamate profiles between accessions Bd21-3 and Bd21. In addition, when compared to agronomical important C3 grasses, more mature Brachypodium stem cell walls have a relative increase in glucose of 48% and a decrease in lignin of 36%. Though differences exists between Brachypodium and agronomical important C3 grasses, Brachypodium distanchyon should be still a useful model system for genetic manipulation of cell wall composition to determine the impact upon functional characteristics such as rumen digestibility or energy conversion efficiency for bioenergy production.

  4. Cell wall composition throughout development for the model grass Brachypodium distachyon

    Science.gov (United States)

    Rancour, David M.; Marita, Jane M.; Hatfield, Ronald D.

    2012-01-01

    Temperate perennial grasses are important worldwide as a livestock nutritive energy source and a potential feedstock for lignocellulosic biofuel production. The annual temperate grass Brachypodium distachyon has been championed as a useful model system to facilitate biological research in agriculturally important temperate forage grasses based on phylogenetic relationships. To physically corroborate genetic predictions, we determined the chemical composition profiles of organ-specific cell walls throughout the development of two common diploid accessions of Brachypodium distachyon, Bd21-3 and Bd21. Chemical analysis was performed on cell walls isolated from distinct organs (i.e., leaves, sheaths, stems, and roots) at three developmental stages of (1) 12-day seedling, (2) vegetative-to-reproductive transition, and (3) mature seed fill. In addition, we have included cell wall analysis of embryonic callus used for genetic transformations. Composition of cell walls based on components lignin, hydroxycinnamates, uronosyls, neutral sugars, and protein suggests that Brachypodium distachyon is similar chemically to agriculturally important forage grasses. There were modest compositional differences in hydroxycinnamate profiles between accessions Bd21-3 and Bd21. In addition, when compared to agronomical important C3 grasses, more mature Brachypodium stem cell walls have a relative increase in glucose of 48% and a decrease in lignin of 36%. Though differences exist between Brachypodium and agronomical important C3 grasses, Brachypodium distachyon should be still a useful model system for genetic manipulation of cell wall composition to determine the impact upon functional characteristics such as rumen digestibility or energy conversion efficiency for bioenergy production. PMID:23227028

  5. Preparation of graphene oxide/polypyrrole/multi-walled carbon nanotube composite and its application in supercapacitors

    International Nuclear Information System (INIS)

    Wang, Bin; Qiu, Jianhui; Feng, Huixia; Sakai, Eiichi

    2015-01-01

    Highlights: • A novel method for synthesizing graphene oxide/polypyrrole/multi-walled nanotube composites. • Investigation of the effects of the mass ratio of GO, CM and Py on the capacitance of prepared composites. • Excellent electrochemical performance of PCMG composites. - Abstract: We report a novel method for preparing graphene oxide/polypyrrole/multi-walled carbon nanotubes (MWCNTs) composites (PCMG). The MWCNTs are treated by sulfuric acid, nitric acid and thionyl chloride, and then composite with graphene oxide and PPy by in suit polymerization. Transition electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results show that in 3-D structure of PCMG composites, PPy chains act as the “bridge” between graphene oxide and chlorinated-MWCNTs. Electrochemical tests reveal that the PCMG1-1 composite has high capacitance of 406.7 F g −1 at current density of 0.5 A g −1 , and the capacitance retention of PCMG1-1 composite is 92% after 1000 cycles

  6. Competitive adsorption of Reactive Orange 16 and Reactive Brilliant Blue R on polyaniline/bacterial extracellular polysaccharides composite-A novel eco-friendly polymer

    Energy Technology Data Exchange (ETDEWEB)

    Janaki, V. [Department of Chemistry, Periyar University, Salem 636011, Tamil Nadu (India); Vijayaraghavan, K. [Singapore-Delft Water Alliance, National University of Singapore, 117577 (Singapore); Ramasamy, A.K. [Department of Chemistry, Periyar University, Salem 636011, Tamil Nadu (India); Lee, Kui-Jae [Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan 570752 (Korea, Republic of); Oh, Byung-Taek, E-mail: btoh@jbnu.ac.kr [Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan 570752 (Korea, Republic of); Kamala-Kannan, Seralathan, E-mail: kannan@jbnu.ac.kr [Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan 570752 (Korea, Republic of)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Competitive adsorption of reactive dyes onto polyaniline/bacterial extracellular polysaccharides composite. Black-Right-Pointing-Pointer The composite have functional groups of both polyaniline and bacterial extracellular polysaccharides. Black-Right-Pointing-Pointer The presence of Reactive Brilliant Blue R diminished the uptake of Reactive Orange 16. Black-Right-Pointing-Pointer Electrostatic interaction was identified as a major mechanism in adsorption process. Black-Right-Pointing-Pointer Reactive Brilliant Blue R and Reactive Orange 16 adsorption was endothermic process. - Abstract: The performance of polyaniline/extracellular polymeric substances (Pn/EPS) composite as an adsorbent to remove the anionic reactive dyes, Reactive Brilliant Blue R (RBBR) and Reactive Orange 16 (RO), was investigated in single and binary systems. The pH{sub pzc} of Pn/EPS composite was calculated as 3.7 through potentiometric mass titration method. Electrostatic interaction between the dye anion and the nitrogen present in the polymer was identified as a major mechanism in adsorption process. Single component isotherms followed the Langmuir model with the maximum adsorption capacity of 0.5775 mmol g{sup -1} for RBBR and 0.4748 mmol g{sup -1} for RO. In binary system, both the reactive dye anions compete with each other and resulted in lower uptake. Binary adsorption data were interpreted well by the Sheindorf-Rehbun-Sheintuch equation as compared to extended Langmuir model with constant interaction factor. Kinetic analysis of single solute followed pseudo-first order model. Thermodynamic studies computed that RBBR and RO adsorption was endothermic, spontaneous, and feasible process.

  7. Influence of the microstructure on the supercapacitive behavior of polyaniline/single-wall carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vinay; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Environment and Energy, KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2006-06-19

    Polyaniline/single-wall carbon nanotube (PANI/SWCNT) composites were prepared by in situ potentiostatic deposition of PANI onto SWCNTs at the potential of 0.75V versus SCE, with the aim to investigate the influence of microstructure on the specific capacitance of PANI/SWCNT composites. It was found that the specific capacitance of the PANI/SWCNT composites is strongly influenced by their microstructure, which is correlated to the wt.% of the PANI deposited onto the SWCNTs. The optimum condition, corresponding to the highest specific capacitance, 463Fg{sup -1} (at 10mAcm{sup -2}), was obtained for 73wt.% PANI deposited onto SWCNTs. The specific capacitance of the PANI/SWCNT composite electrode was highly stable, with a capacitive decrease of 5% during the first 500 cycles and just 1% during the next 1000 cycles, indicative of the excellent cyclic stability of the composite for supercapacitor applications. (author)

  8. Static resistance function for steel-plate composite (SC) walls subject to impactive loading

    Energy Technology Data Exchange (ETDEWEB)

    Bruhl, Jakob C., E-mail: jbruhl@purdue.edu; Varma, Amit H., E-mail: ahvarma@purdue.edu; Kim, Joo Min, E-mail: kim1493@purdue.edu

    2015-12-15

    Highlights: • An idealized static resistance function for SC walls is proposed. • The influence of design parameters on static resistance is explained. • SDOF models can accurately estimate global response of SC walls to missile impact. - Abstract: Steel-plate composite (SC) walls consist of a plain concrete core reinforced with two steel faceplates on the surfaces. Modules (consisting of steel faceplates, shear connectors and tie-bars) can be shop-fabricated and shipped to the site for erection and concrete casting, which expedites construction schedule and thus economy. SC structures have recently been used in nuclear power plant designs and are being considered for the next generation of small modular reactors. Design for impactive and impulsive loading is an important consideration for SC walls in safety-related nuclear facilities. The authors have previously developed design methods to prevent local failure (perforation) of SC walls due to missile impact. This paper presents the development of static resistance functions for use in single-degree-of-freedom (SDOF) analyses to predict the maximum displacement response of SC walls subjected to missile impact and designed to resist local failure (perforation). The static resistance function for SC walls is developed using results of numerical analyses and parametric studies conducted using benchmarked 3D finite element (FE) models. The influence of various design parameters are discussed and used to develop idealized bilinear resistance functions for SC walls with fixed edges and simply supported edges. Results from dynamic non-linear FE analysis of SC panels subjected to rigid missile impact are compared with the maximum displacements predicted by SDOF analyses using the bilinear resistance function.

  9. Static resistance function for steel-plate composite (SC) walls subject to impactive loading

    International Nuclear Information System (INIS)

    Bruhl, Jakob C.; Varma, Amit H.; Kim, Joo Min

    2015-01-01

    Highlights: • An idealized static resistance function for SC walls is proposed. • The influence of design parameters on static resistance is explained. • SDOF models can accurately estimate global response of SC walls to missile impact. - Abstract: Steel-plate composite (SC) walls consist of a plain concrete core reinforced with two steel faceplates on the surfaces. Modules (consisting of steel faceplates, shear connectors and tie-bars) can be shop-fabricated and shipped to the site for erection and concrete casting, which expedites construction schedule and thus economy. SC structures have recently been used in nuclear power plant designs and are being considered for the next generation of small modular reactors. Design for impactive and impulsive loading is an important consideration for SC walls in safety-related nuclear facilities. The authors have previously developed design methods to prevent local failure (perforation) of SC walls due to missile impact. This paper presents the development of static resistance functions for use in single-degree-of-freedom (SDOF) analyses to predict the maximum displacement response of SC walls subjected to missile impact and designed to resist local failure (perforation). The static resistance function for SC walls is developed using results of numerical analyses and parametric studies conducted using benchmarked 3D finite element (FE) models. The influence of various design parameters are discussed and used to develop idealized bilinear resistance functions for SC walls with fixed edges and simply supported edges. Results from dynamic non-linear FE analysis of SC panels subjected to rigid missile impact are compared with the maximum displacements predicted by SDOF analyses using the bilinear resistance function.

  10. Quantitative CT: Associations between Emphysema, Airway Wall Thickness and Body Composition in COPD

    DEFF Research Database (Denmark)

    Rutten, Erica P A; Grydeland, Thomas B; Pillai, Sreekumar G

    2011-01-01

    The objective of the present study was to determine the association between CT phenotypes-emphysema by low attenuation area and bronchitis by airway wall thickness-and body composition parameters in a large cohort of subjects with and without COPD. In 452 COPD subjects and 459 subjects without COPD......, CT scans were performed to determine emphysema (%LAA), airway wall thickness (AWT-Pi10), and lung mass. Muscle wasting based on FFMI was assessed by bioelectrical impedance. In both the men and women with COPD, FFMI was negatively associated with %LAA. FMI was positively associated with AWT-Pi10...... in both subjects with and without COPD. Among the subjects with muscle wasting, the percentage emphysema was high, but the predictive value was moderate. In conclusion, the present study strengthens the hypothesis that the subgroup of COPD cases with muscle wasting have emphysema. Airway wall thickness...

  11. Quantitative CT: Associations between Emphysema, Airway Wall Thickness and Body Composition in COPD

    DEFF Research Database (Denmark)

    Rutten, Erica P A; Grydeland, Thomas B; Pillai, Sreekumar G

    2011-01-01

    , CT scans were performed to determine emphysema (%LAA), airway wall thickness (AWT-Pi10), and lung mass. Muscle wasting based on FFMI was assessed by bioelectrical impedance. In both the men and women with COPD, FFMI was negatively associated with %LAA. FMI was positively associated with AWT-Pi10......The objective of the present study was to determine the association between CT phenotypes-emphysema by low attenuation area and bronchitis by airway wall thickness-and body composition parameters in a large cohort of subjects with and without COPD. In 452 COPD subjects and 459 subjects without COPD...... in both subjects with and without COPD. Among the subjects with muscle wasting, the percentage emphysema was high, but the predictive value was moderate. In conclusion, the present study strengthens the hypothesis that the subgroup of COPD cases with muscle wasting have emphysema. Airway wall thickness...

  12. Compositional analysis of Chinese water chestnut (Eleocharis dulcis) cell-wall material from parenchyma, epidermis, and subepidermal tissues.

    Science.gov (United States)

    Grassby, Terri; Jay, Andrew J; Merali, Zara; Parker, Mary L; Parr, Adrian J; Faulds, Craig B; Waldron, Keith W

    2013-10-09

    Chinese water chestnut (Eleocharis dulcis (Burman f.) Trin ex Henschel) is a corm consumed globally in Oriental-style cuisine. The corm consists of three main tissues, the epidermis, subepidermis, and parenchyma; the cell walls of which were analyzed for sugar, phenolic, and lignin content. Sugar content, measured by gas chromatography, was higher in the parenchyma cell walls (931 μg/mg) than in the subepidermis (775 μg/mg) or epidermis (685 μg/mg). The alkali-extractable phenolic content, measured by high-performance liquid chromatography, was greater in the epidermal (32.4 μg/mg) and subepidermal cell walls (21.7 μg/mg) than in the cell walls of the parenchyma (12.3 μg/mg). The proportion of diferulic acids was higher in the parenchyma. The Klason lignin content of epidermal and subepidermal cell walls was ~15%. Methylation analysis of Chinese water chestnut cell-wall polysaccharides identified xyloglucan as the predominant hemicellulose in the parenchyma for the first time, and also a significant pectin component, similar to other nongraminaceous monocots.

  13. Implication of multi-walled carbon nanotubes on polymer/graphene composites

    International Nuclear Information System (INIS)

    Araby, Sherif; Saber, Nasser; Ma, Xing; Kawashima, Nobuyuki; Kang, Hailan; Shen, Heng; Zhang, Liqun; Xu, Jian; Majewski, Peter; Ma, Jun

    2015-01-01

    Highlights: • Influence of adding carbon nanotubes (CNTs) into elastomer/graphene composites. • Multi-walled CNTs work supplementally to GnPs by forming conductive networks. • The findings illuminate marked synergistic effect between MWCNTs and graphene sheets. - Abstract: Graphene sheets stack in polymer matrices while multi-walled carbon nanotubes (MWCNTs) entangle themselves, forming two daunting challenges in the design and fabrication of polymer composites. Both challenges have been simultaneously addressed in this study by hybridizing the two nanomaterials through melt compounding to develop elastomer/graphene platelet/MWCNT (3-phase) composites, where MWCNTs were fixed at 2.8 vol% (5 wt%) for all fractions. We investigated the composites’ structure and properties, and compared the 3-phase composites with elastomer/graphene platelet (2-phase) composites. MWCNTs may bridge graphene platelets (GnPs) and promote their dispersion in the matrix, which would provide more interface area between the matrix and the fillers. MWCNTs worked supplementally to GnPs by forming conductive networks, where MWCNTs acted as long nanocables to transport electrons and stress while GnPs served as interconnection sites between the tubes forming local conductive paths. This produced a percolation threshold of electrical conductivity at 2.3 vol% for 3-phase composites, 88% lower than that of 2-phase composites. At 26.7 vol% of total filler content (MWCNTs + GnPs), tensile strength, Young’s modulus and tear strength showed respectively 303%, 115%, 155% further improvements over those of 2-phase composites. These improvements are originated from the synergistic effect between GnPs and MWCNTs. The conducting elastomeric composites developed would potentially open the door for applications in automotive and aerospace industries

  14. Single walled carbon nanotube network—Tetrahedral amorphous carbon composite film

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, Ajai, E-mail: ajai.iyer@aalto.fi; Liu, Xuwen; Koskinen, Jari [Department of Materials Science and Engineering, School of Chemical Technology, Aalto University, POB 16200, 00076 Espoo (Finland); Kaskela, Antti; Kauppinen, Esko I. [NanoMaterials Group, Department of Applied Physics, School of Science, Aalto University, POB 15100, 00076 Espoo (Finland); Johansson, Leena-Sisko [Department of Forest Products Technology, School of Chemical Technology, Aalto University, POB 16400, 00076 Espoo (Finland)

    2015-06-14

    Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measurements prove the presence of high quality sp{sup 3} bonded ta-C coating on the SWCNTN. Raman spectroscopy suggests that the single wall carbon nanotubes (SWCNTs) forming the network survived encapsulation in the ta-C coating. Nano-mechanical testing suggests that the ta-C coated SWCNTN has superior wear performance compared to uncoated SWCNTN.

  15. Microwave absorbing properties of polyaniline/multi-walled carbon nanotube composites with various polyaniline contents

    International Nuclear Information System (INIS)

    Ting, T.H.; Jau, Y.N.; Yu, R.P.

    2012-01-01

    Polyaniline/multi-walled carbon nanotube (PANI/MWNT) composites were synthesized using in situ polymerization at different aniline/multi-walled carbon nanotube weight ratios (Ani/MWNT = 1/2, 1/1, 2/1 and 3/1) and introduced into an epoxy resin to act as a microwave absorber. The spectroscopic characterization of the process of formation of PANI/MWNT composites were studied using Fourier transform infrared spectroscopy, an ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. The microwave absorbing properties were investigated by measuring complex permittivity, complex permeability and reflection loss in the 2-18 and 18-40 GHz microwave frequency range, using the free space method. The results showed that the addition of PANI was useful for achieving a large absorption over a wide frequency range, especially for higher frequency values.

  16. Experimental Study of Multi-Walled Composite Shell Fragments under Thermal Force Effects

    Directory of Open Access Journals (Sweden)

    L. P. Tairova

    2015-01-01

    Full Text Available Multi-walled composite shells are a relatively new prospective type of load carrying structures for rocket and space engineering. These CFRP structures are produced by injection and infusion methods and have several advantages in comparison with common structures such as stringer-frame, grid and sandwich structures with a light core. In particular, those have more structural parameters, which enable one to control mechanical properties of the structure, and this is important in designing the load carrying structures of different purpose.Presently, there are few national and foreign publications on experimental investigations of mechanical properties of multi-walled shells. That is why the objective of the paper is to conduct the experimental study of deformation and failure processes of a multi-walled panel both under steady-state heating and under unsteady-state one.The paper presents the results of two tests: (1 the study of deformation and failure modes under compression and complete heating up to a specified temperature and (2 validation of working capability of multi-walled samples under single-side heating and compression simulating a start and flight version of the “ Proton” launch vehicle.Experimental results have shown that average elastic properties of multi-walled samples slightly depend on temperature for the studied range (from room temperature up to 195C while strength properties considerably decrease with increasing temperature, and this is typical for CFRP structures under compression. However, under unsteady-state short-term heating the structure has a strength that exceeds the minimal necessary strength of load carrying structures of the “Proton” launch vehicle (the samples satisfy simulated start conditions of the “Proton” launch vehicle. This is because of a low heat conductivity of the multi-walled core: an unheated sheet holds a low temperature and high load carrying capacity.Obtained results can be used in

  17. Effect of annealing temperature on electrochemical characteristics of ruthenium oxide/multi-walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Min-Kang [Department of Chemistry, Inha University, 253, Incheon 402-751 (Korea, Republic of); Saouab, Abdelghani [Department of Mechanical Engineering, University of Le Havre, Place Robert Schuman, BP 4006, 76610 Le Havre (France); Park, Soo-Jin, E-mail: sjpark@inha.ac.k [Department of Chemistry, Inha University, 253, Incheon 402-751 (Korea, Republic of)

    2010-02-25

    The preparation and characterization of high-surface-area ruthenium oxide (RuO{sub 2})/multi-walled carbon nanotubes (MWCNTs) composite electrodes for use in supercapacitors is reported in this work. The RuO{sub 2}/MWCNTs composites were prepared by the polyol process of RuO{sub 2} into MWCNTs and by Ru annealing in air before mixed with MWCNTs. The chemically oxidized and annealed Ru nanoparticles contribute a pseudocapacitance to the electrodes and dramatically improve the energy storage characteristics of the MWCNTs. These composites annealed at 200 deg. C demonstrate specific capacitances in excess of 130 F/g in comparison to 80 F/g for pristine MWCNTs. The annealing temperature is found to play an important role, as it affects the electrochemical performance of annealed RuO{sub 2}/MWCNTs composites critically due to its influence on the diffusion of protons into the structure.

  18. Sugar composition of the pectic polysaccharides of charophytes, the closest algal relatives of land-plants: presence of 3-O-methyl-D-galactose residues.

    Science.gov (United States)

    O'Rourke, Christina; Gregson, Timothy; Murray, Lorna; Sadler, Ian H; Fry, Stephen C

    2015-08-01

    During evolution, plants have acquired and/or lost diverse sugar residues as cell-wall constituents. Of particular interest are primordial cell-wall features that existed, and in some cases abruptly changed, during the momentous step whereby land-plants arose from charophytic algal ancestors. Polysaccharides were extracted from four charophyte orders [Chlorokybales (Chlorokybus atmophyticus), Klebsormidiales (Klebsormidium fluitans, K. subtile), Charales (Chara vulgaris, Nitella flexilis), Coleochaetales (Coleochaete scutata)] and an early-diverging land-plant (Anthoceros agrestis). 'Pectins' and 'hemicelluloses', operationally defined as extractable in oxalate (100 °C) and 6 m NaOH (37 °C), respectively, were acid- or Driselase-hydrolysed, and the monosaccharides analysed chromatographically. One unusual monosaccharide, 'U', was characterized by (1)H/(13)C-nuclear magnetic resonance spectroscopy and also enzymically. 'U' was identified as 3-O-methyl-D-galactose (3-MeGal). All pectins, except in Klebsormidium, contained acid- and Driselase-releasable galacturonate, suggesting homogalacturonan. All pectins, without exception, released rhamnose and galactose on acid hydrolysis; however, only in 'higher' charophytes (Charales, Coleochaetales) and Anthoceros were these sugars also efficiently released by Driselase, suggesting rhamnogalacturonan-I. Pectins of 'higher' charophytes, especially Chara, contained little arabinose, instead possessing 3-MeGal. Anthoceros hemicelluloses were rich in glucose, xylose, galactose and arabinose (suggesting xyloglucan and arabinoxylan), none of which was consistently present in charophyte hemicelluloses. Homogalacturonan is an ancient streptophyte feature, albeit secondarily lost in Klebsormidium. When conquering the land, the first embryophytes already possessed rhamnogalacturonan-I. In contrast, charophyte and land-plant hemicelluloses differ substantially, indicating major changes during terrestrialization. The presence of 3

  19. Seasonal biochemical changes in composition of body wall tissues of sea cucumber Apostichopus japonicus

    Science.gov (United States)

    Gao, Fei; Xu, Qiang; Yang, Hongsheng

    2011-03-01

    Seasonal Variation in proximate, amino acid and fatty acid composition of the body wall of sea cucumber Apostichopus japonicus was evaluated. The proximate composition, except for ash content, changed significantly among seasons ( P<0.05). Alanine, glycine, glutamic acid and asparagic acid were the most abundant amino acids. Total amino acid and essential amino acid Contents both varied clearly with seasons ( P<0.05). 16:0 and 16:ln7 were the primary saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) respectively for all months. EPA (20:5n-3), AA (20:4n-6) and DHA (22:6n-3) were the major polyunsaturated fatty acids (PUFA). The proportions of SFA and PUFA yielded significant seasonal variations ( P<0.001), but MUFA did not changed significantly. The results indicated that the biochemical compositions of the body wall in A. japonicus were significantly influenced by seasons and that the body wall tissue is an excellent source of protein, MUFA and n-3 PUFA for humans.

  20. The Cell Wall of the Human Fungal Pathogen Aspergillus fumigatus: Biosynthesis, Organization, Immune Response, and Virulence.

    Science.gov (United States)

    Latgé, Jean-Paul; Beauvais, Anne; Chamilos, Georgios

    2017-09-08

    More than 90% of the cell wall of the filamentous fungus Aspergillus fumigatus comprises polysaccharides. Biosynthesis of the cell wall polysaccharides is under the control of three types of enzymes: transmembrane synthases, which are anchored to the plasma membrane and use nucleotide sugars as substrates, and cell wall-associated transglycosidases and glycosyl hydrolases, which are responsible for remodeling the de novo synthesized polysaccharides and establishing the three-dimensional structure of the cell wall. For years, the cell wall was considered an inert exoskeleton of the fungal cell. The cell wall is now recognized as a living organelle, since the composition and cellular localization of the different constitutive cell wall components (especially of the outer layers) vary when the fungus senses changes in the external environment. The cell wall plays a major role during infection. The recognition of the fungal cell wall by the host is essential in the initiation of the immune response. The interactions between the different pattern-recognition receptors (PRRs) and cell wall pathogen-associated molecular patterns (PAMPs) orientate the host response toward either fungal death or growth, which would then lead to disease development. Understanding the molecular determinants of the interplay between the cell wall and host immunity is fundamental to combatting Aspergillus diseases.

  1. Chemical composition and antioxidant activities in immumosuppressed mice of polysaccharides isolated from Mosla chinensis Maxim cv. jiangxiangru.

    Science.gov (United States)

    Li, Jing-En; Nie, Shao-Ping; Xie, Ming-Yong; Huang, Dan-Fei; Wang, Yu-Ting; Li, Chang

    2013-10-01

    Polysaccharide MP was isolated from Mosla chinensis Maxim cv. jiangxiangru. It was composed of rhamnose, arabinose, xylose, mannose, glucose and galactose in a molar ratio of 5.364:12.260:3.448:12.260:32.567:30.651, with 11.00%±0.24% uronic acid and 9.046%±0.04% protein. Its antioxidant activity on the cyclophosphamide-induced immunosuppressed mice was investigated. The spleen and the thymus indices were investigated, and the biochemical parameters were evaluated in three organs (liver, heart and kidney). MP was able to overcome the cyclophosphamide-induced immunosuppression and can significantly raise the T-AOC, CAT, SOD and GSH-PX level. It also raised the spleen and thymus indices and decreased the MDA level in mice. MP could play an important role during the prevention process of oxidative damage in immunological system. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. In vitro prebiotic effects of seaweed polysaccharides

    Science.gov (United States)

    Chen, Xiaolin; Sun, Yuhao; Hu, Linfeng; Liu, Song; Yu, Huahua; Xing, Rong'e.; Li, Rongfeng; Wang, Xueqin; Li, Pengcheng

    2017-09-01

    Although prebiotic activities of alginate and agar oligosaccharides isolated from seaweeds have been reported, it remains unknown whether seaweed polysaccharides have prebiotic activity. In this study, we isolated polysaccharides from four species of seaweeds, such as Grateloupia filicina (GFP), Eucheuma spinosum (ESP), Ulva pertusa (UPP), and Ascophyllum nodosum (ANP), and characterized their structures and prebiotic effects in vitro. The results showed that these polysaccharides were different in total sugar and sulfate contents as well as monosaccharide composition. GFP and ESP significantly promoted bifidobacterium proliferation and 0.1% ESP and 0.4% GFP resulted in the highest proliferation rates of beneficial bacteria, whereas UPP and ANP inhibited the growth of beneficial bacteria at all tested concentrations (0.1%-0.5%). The different behaviors of the four seaweed-originated polysaccharides might be reflected by differences in monosaccharide composition and structure. Therefore, polysaccharides isolated from GFP and ESP could be utilized as prebiotics. However, more studies must be carried out in vivo.

  3. Synthesis of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes composite for supercapacitance application

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Rajesh Kr., E-mail: r05bhu@gmail.com [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Xingjue, Wang [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Kumar, Vinod [Department of Zoology, Banaras Hindu University, Varanasi (India); Srivastava, Anchal [Department of Physics, Banaras Hindu University, Varanasi (India); Singh, Vidya Nand [CSIR-National Physical Laboratory, New Delhi (India)

    2014-11-05

    Highlights: • We are reporting supercapacitance performance of BI-GO/MWCNTs composite. • The specific capacitance of BI-GO/MWCNTs is 275 and 460 F/g at 200 and 5 mV/s scan rate. • This composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate. - Abstract: We are reporting the fabrication, characterizations and supercapacitance performance of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes (BI-GO/MWCNTs) composite. The synthesis of BI-GO materials involves cyclization reaction of carboxylic groups on GO among the hydroxyl and amino groups on o-phenylenediamine. The BI-GO/MWCNTs composite has been fabricated via in situ reduction of BI-GO using hydrazine in presence of MWCNTs. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize its surface and elemental composition. The uniform dispersion of MWCNTs with BI-GO helps to improve the charge transfer reaction during electrochemical process. The specific capacitance of BI-GO/MWCNTs composite is 275 and 460 F/g at 200 and 5 mV/s scan rate in 1 mol/L aqueous solution of H{sub 2}SO{sub 4}. This BI-GO/MWCNTs composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate, which represents its good electrochemical stability.

  4. Synthesis of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes composite for supercapacitance application

    International Nuclear Information System (INIS)

    Srivastava, Rajesh Kr.; Xingjue, Wang; Kumar, Vinod; Srivastava, Anchal; Singh, Vidya Nand

    2014-01-01

    Highlights: • We are reporting supercapacitance performance of BI-GO/MWCNTs composite. • The specific capacitance of BI-GO/MWCNTs is 275 and 460 F/g at 200 and 5 mV/s scan rate. • This composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate. - Abstract: We are reporting the fabrication, characterizations and supercapacitance performance of benzimidazole-grafted graphene oxide/multi-walled carbon nanotubes (BI-GO/MWCNTs) composite. The synthesis of BI-GO materials involves cyclization reaction of carboxylic groups on GO among the hydroxyl and amino groups on o-phenylenediamine. The BI-GO/MWCNTs composite has been fabricated via in situ reduction of BI-GO using hydrazine in presence of MWCNTs. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) have been used to characterize its surface and elemental composition. The uniform dispersion of MWCNTs with BI-GO helps to improve the charge transfer reaction during electrochemical process. The specific capacitance of BI-GO/MWCNTs composite is 275 and 460 F/g at 200 and 5 mV/s scan rate in 1 mol/L aqueous solution of H 2 SO 4 . This BI-GO/MWCNTs composite has shown 224 F/g capacitance after 1300 cycles at 200 mV/s scan rate, which represents its good electrochemical stability

  5. In-vitro and in-vivo design and validation of an injectable polysaccharide-hydroxyapatite composite material for sinus floor augmentation.

    Science.gov (United States)

    Fricain, J C; Aid, R; Lanouar, S; Maurel, D B; Le Nihouannen, D; Delmond, S; Letourneur, D; Amedee Vilamitjana, J; Catros, S

    2018-04-07

    Polysaccharide-based composite matrices consisting of natural polysaccharides, pullulan and dextran supplemented with hydroxyapatite (Matrix-HA) have recently been developed. The principal objective of this study was to evaluate the capacities of this composite material to promote new bone formation in a sinus lift model in the sheep. Secondary objectives were to evaluate in vitro properties of the material regarding cell adhesion and proliferation. In this report, once such composite matrix was prepared as injectable beads after dispersion in a physiological buffer, and evaluated using a large animal model (sheep) for a sinus lift procedure. In vitro studies revealed that these microbeads (250-550μm in diameter) allow vascular cell adhesion and proliferation of Endothelial Cells (EC) after 1 and 7 days of culture. In vivo studies were performed in 12 adult sheep, and newly formed tissue was analyzed by Cone Beam Computed Tomography (CBCT scanning electron microscopy (SEM) and by histology 3 and 6 months post-implantation. CBCT analyses at the implantation time revealed the radiolucent properties of these matrices. Quantitative analysis showed an increase of a dense mineralized tissue in the Matrix-HA group up to 3 months of implantation. The mineralized volume over total volume after 6 months reached comparable values to those obtained for Bio-Oss ® used as positive control. Histological examination confirmed that the Matrix-HA did not induce any long term inflammatory events, and promoted direct contact between the osteoid tissue and lamellar bone structures and beads. After 6 months, we observed a dense network of osteocytes surrounding both biomaterials as well as a newly vascularized formed tissue in close contact to the biomaterials. In conclusion, the absence of animal components in Matrix-HA, the osteoconductive property of Matrix-HA in sheep, resulting in a dense bone and vascularized tissue, and the initial radiolucent property to follow graft

  6. Wet spinning of PVA composite fibers with a large fraction of multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Dengpan Lai

    2015-10-01

    Full Text Available PVA composites fibers with a large fraction of multi-walled carbon nanotubes modified by both covalent and non-covalent functionalization were produced by a wet-spinning process. Model XQ-1 tensile tester, thermogravimetric analysis, scanning electron microscopy, differential scanning calorimetry, and wide-angle X-ray diffraction were used to characterize the properties of PVA/MWNT composite fibers. The TGA results suggested that MWNTs content in composite fibers were ranged from 5.3 wt% to 27.6 wt%. The mechanical properties of PVA/MWNT composite fibers were obviously superior to pure PVA fiber. The Young׳s modulus of composite fibers enhanced with increasing the content of MWNTs, and it rised gradually from 6.7 GPa for the pure PVA fiber to 12.8 GPa for the composite fibers with 27.6 wt% MWNTs. Meanwhile, the tensile strength increased gradually from 0.39 GPa for the pure PVA fiber to 0.74 GPa for the composite fibers with 14.4 wt% MWNTs. Nevertheless, the tensile strength of the composite fibers decreased as the MWNTs content up to 27.6 wt%. SEM results indicated that the MWNTs homogeneously dispersed in the composite fibers, however some agglomerates also existed when the content of MWNTs reached 27.6 wt%. DSC results proved strong interfacial interaction between MWNTs and PVA chain, which benefited composite fibers in the efficient stress-transfer. WXAD characterization showed that the orientation of PVA molecules declined from 94.1% to 90.9% with the increasing of MWNTs content. The good dispersibility of MWNTs throughout PVA matrix and efficient stress-transfer between MWNTs and PVA matrix may contributed to significant enhancement in the mechanical properties.

  7. Magnetic orientation of single-walled carbon nanotubes or their composites using polymer wrapping

    Directory of Open Access Journals (Sweden)

    Hiroaki Yonemura et al

    2008-01-01

    Full Text Available The magnetic orientation of single-walled carbon nanotubes (SWNTs or the SWNT composites wrapped with polymer using poly[2-methoxy-5-(2'-ethylhexyloxy-1,4-phenylene vinylene] (MEHPPV as the conducting polymer were examined. The formation of SWNT/MEHPPV composites was confirmed by examining absorption and fluorescence spectra. The N,N-dimethylformamide solution of SWNT/MEHPPV composites or the aqueous solution of the shortened SWNTs was introduced dropwise onto a mica or glass plate. The magnetic processing of the composites or the SWNTs was carried out using a superconducting magnet with a horizontal direction (8 T. The AFM images indicated that the SWNT/MEHPPV composites or the SWNTs were oriented randomly without magnetic processing, while with magnetic processing (8 T, they were oriented with the tube axis of the composites or the SWNTs parallel to the magnetic field. In polarized absorption spectra of SWNT/MEHPPV composites on glass plates without magnetic processing, the absorbance due to semiconducting SWNT in the near-IR region in horizontal polarized light was almost the same as that in vertical polarized light. In contrast, with magnetic processing (8 T, the absorbance due to semiconducting SWNT in the horizontal polarization direction against the direction of magnetic field was stronger than that in the vertical polarization direction. Similar results were obtained from the polarized absorption spectra for the shortened SWNTs. These results of polarized absorption spectra also support the magnetic orientation of the SWNT/MEHPPV composites or the SWNTs. On the basis of a comparison of the composites and the SWNTs alone, the magnetic orientation of SWNT/MEHPPV composites is most likely ascribable to the anisotropy in susceptibilities of SWNTs.

  8. 2003 Plant Cell Walls Gordon Conference

    Energy Technology Data Exchange (ETDEWEB)

    Daniel J. Cosgrove

    2004-09-21

    This conference will address recent progress in many aspects of cell wall biology. Molecular, genetic, and genomic approaches are yielding major advances in our understanding of the composition, synthesis, and architecture of plant cell walls and their dynamics during growth, and are identifying the genes that encode the machinery needed to make their biogenesis possible. This meeting will bring together international scientists from academia, industry and government labs to share the latest breakthroughs and perspectives on polysaccharide biosynthesis, wood formation, wall modification, expansion and interaction with other organisms, and genomic & evolutionary analyses of wall-related genes, as well as to discuss recent ''nanotechnological'' advances that take wall analysis to the level of a single cell.

  9. Dynamic changes in transcriptome and cell wall composition underlying brassinosteroid-mediated lignification of switchgrass suspension cells.

    Science.gov (United States)

    Rao, Xiaolan; Shen, Hui; Pattathil, Sivakumar; Hahn, Michael G; Gelineo-Albersheim, Ivana; Mohnen, Debra; Pu, Yunqiao; Ragauskas, Arthur J; Chen, Xin; Chen, Fang; Dixon, Richard A

    2017-01-01

    Plant cell walls contribute the majority of plant biomass that can be used to produce transportation fuels. However, the complexity and variability in composition and structure of cell walls, particularly the presence of lignin, negatively impacts their deconstruction for bioenergy. Metabolic and genetic changes associated with secondary wall development in the biofuel crop switchgrass ( Panicum virgatum ) have yet to be reported. Our previous studies have established a cell suspension system for switchgrass, in which cell wall lignification can be induced by application of brassinolide (BL). We have now collected cell wall composition and microarray-based transcriptome profiles for BL-induced and non-induced suspension cultures to provide an overview of the dynamic changes in transcriptional reprogramming during BL-induced cell wall modification. From this analysis, we have identified changes in candidate genes involved in cell wall precursor synthesis, cellulose, hemicellulose, and pectin formation and ester-linkage generation. We have also identified a large number of transcription factors with expression correlated with lignin biosynthesis genes, among which are candidates for control of syringyl (S) lignin accumulation. Together, this work provides an overview of the dynamic compositional changes during brassinosteroid-induced cell wall remodeling, and identifies candidate genes for future plant genetic engineering to overcome cell wall recalcitrance.

  10. Measurement and modification of first-wall surface composition in the Oak Ridge Tokamak (ORMAK)

    International Nuclear Information System (INIS)

    Clausing, R.E.; Emerson, L.C.; Heatherly, L.; Colchin, R.J.; Twichell, J.C.

    1975-01-01

    Impurities coming into the plasma from the walls of present-day toroidal plasma confinement devices modify plasma behavior substantially. Small fractions of high-Z ions in the plasma greatly decrease plasma temperatures and increase plasma energy losses. Impurities from the ''first-wall'' in ORMAK were studied. Auger electron spectroscopy, soft x-ray appearance potential spectroscopy, and other surface sensitive techniques were used to characterize the surface composition of the first wall and to develop methods to remove carbon and oxygen. Oxygen glow discharge cleaning has been shown, in the laboratory, to be an effective way of removing carbon from gold films (simulated ORMAK linear material) and the use of oxygen discharge cleaning in ORMAK has resulted in a decrease in plasma contamination, a 50 percent increase in plasma current and an accompanying increase in plasma temperature. In spite of these improvements the walls of ORMAK are far from clean. Substantial amounts of carbon, oxygen, iron and other elements remain. (auth)

  11. Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in sorghum bicolor

    Science.gov (United States)

    The phenylpropanoid biosynthesis pathway that generates lignin subunits represents a significant target to alter the abundance and composition of lignin. The major regulators of phenylpropanoid metabolism are myb transcription factors, which have been shown to modulate secondary cell wall compositi...

  12. The inaccuracy of conventional one-dimensional parallel thermal resistance circuit model for two-dimensional composite walls

    International Nuclear Information System (INIS)

    Wong, K.-L.; Hsien, T.-L.; Hsiao, M.-C.; Chen, W.-L.; Lin, K.-C.

    2008-01-01

    This investigation is to show that two-dimensional steady state heat transfer problems of composite walls should not be solved by the conventionally one-dimensional parallel thermal resistance circuits (PTRC) model because the interface temperatures are not unique. Thus PTRC model cannot be used like its conventional recognized analogy, parallel electrical resistance circuits (PERC) model which has the unique node electric voltage. Two typical composite wall examples, solved by CFD software, are used to demonstrate the incorrectness. The numerical results are compared with those obtained by PTRC model, and very large differences are observed between their results. This proves that the application of conventional heat transfer PTRC model to two-dimensional composite walls, introduced in most heat transfer text book, is totally incorrect. An alternative one-dimensional separately series thermal resistance circuit (SSTRC) model is proposed and applied to the two-dimensional composite walls with isothermal boundaries. Results with acceptable accuracy can be obtained by the new model

  13. Extraction optimization and characterization of polysaccharide ...

    African Journals Online (AJOL)

    Keywords: Pinellia rhizoma, Polysaccharides Optimization extraction, Monosaccharide composition,. Antioxidant ..... mean yield of PRP was 2.47 %. Therefore ... Table 3: Analysis of variance (ANOVA) for the fitted quadratic polynomial model.

  14. Development of pH-sensitive tamarind seed polysaccharide-alginate composite beads for controlled diclofenac sodium delivery using response surface methodology.

    Science.gov (United States)

    Nayak, Amit Kumar; Pal, Dilipkumar

    2011-11-01

    The present study deals with the development of novel pH-sensitive tamarind seed polysaccharide (TSP)-alginate composite beads for controlled diclofenac sodium delivery using response surface methodology by full 3(2) factorial design. The effect of polymer-blend ratio (sodium alginate:TSP) and cross-linker (CaCl(2)) concentration on the drug encapsulation efficiency (DEE, %) and drug release from diclofenac sodium loaded TSP-alginate composite beads prepared by ionotropic gelation was optimized. The observed responses were coincided well with the predicted values by the experimental design. The DEE (%) of these beads containing diclofenac sodium was within the range between 72.23±2.14 and 97.32±4.03% with sustained in vitro drug release (69.08±2.36-96.07±3.54% in 10 h). The in vitro drug release from TSP-alginate composite beads containing diclofenac sodium was followed by controlled-release pattern (zero-order kinetics) with case-II transport mechanism. Particle size range of these beads was 0.71±0.03-1.33±0.04 mm. The swelling and degradation of the developed beads were influenced by different pH of the test medium. The FTIR and NMR analyses confirmed the compatibility of the diclofenac sodium with TSP and sodium alginate used to prepare the diclofenac sodium loaded TSP-alginate composite beads. The newly developed TSP-alginate composite beads are suitable for controlled delivery of diclofenac sodium for prolonged period. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. The surface modifications of multi-walled carbon nanotubes for multi-walled carbon nanotube/poly(ether ether ketone) composites

    International Nuclear Information System (INIS)

    Cao, Zongshuang; Qiu, Li; Yang, Yongzhen; Chen, Yongkang; Liu, Xuguang

    2015-01-01

    Graphical abstract: Multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites incorporating surface modified multi-walled carbon nanotubes (MWCNTs) as fillers were fabricated in a solution blending method in order to explore the dynamic mechanical and tribological properties of MWCNT/PEEK composites systematically. It is evident that surface modifications of MWCNTs have a significant impact on dispersibility of MWCNTs in PEEK, dynamic mechanical and tribological properties of MWCNT/PEEK composites. Typically, a clear effect of surface modifications of MWCNTs on tribological properties of MWCNT/PEEK composites was observed. A significant reduction in frictional coefficient of MWCNT/PEEK composites with the MWCNTs modified with ethanolamine has been achieved and the self-lubricating film on their worn surfaces was also observed. - Highlights: • The dispersibility of surface modified MWCNTs in PEEK has been studied. • MWCNTs modified with ethanolamine have showed a good dispersion in PEEK. • Surface modifications of MWCNTs have a significant impact on both dynamic mechanical and tribological properties of MWCNT/PEEK composites. - Abstract: The effects of surface modifications of multi-walled carbon nanotubes (MWCNTs) on the morphology, dynamic mechanical and tribological properties of multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites have been investigated. MWCNTs were treated with mixed acids to obtain acid-functionalized MWCNTs. Then the acid-functionalized MWCNTs were modified with ethanolamine (named e-MWCNTs). The MWCNT/PEEK composites were prepared by a solution-blending method. A more homogeneous distribution of e-MWCNTs within the composites was found with scanning electron microscopy. Dynamic mechanical analysis demonstrated a clear increase in the storage modulus of e-MWCNT/PEEK composites because of the improved interfacial adhesion strength between e-MWCNTs and PEEK. Furthermore, the presence of e

  16. The surface modifications of multi-walled carbon nanotubes for multi-walled carbon nanotube/poly(ether ether ketone) composites

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Zongshuang [Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Research Center of Advanced Material Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Qiu, Li [Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Yongzhen, E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Research Center of Advanced Material Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Chen, Yongkang, E-mail: y.k.chen@herts.ac.uk [Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); University of Hertfordshire, School of Engineering and Technology, Hatfield, Hertfordshire AL10 9AB (United Kingdom); Liu, Xuguang [Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2015-10-30

    Graphical abstract: Multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites incorporating surface modified multi-walled carbon nanotubes (MWCNTs) as fillers were fabricated in a solution blending method in order to explore the dynamic mechanical and tribological properties of MWCNT/PEEK composites systematically. It is evident that surface modifications of MWCNTs have a significant impact on dispersibility of MWCNTs in PEEK, dynamic mechanical and tribological properties of MWCNT/PEEK composites. Typically, a clear effect of surface modifications of MWCNTs on tribological properties of MWCNT/PEEK composites was observed. A significant reduction in frictional coefficient of MWCNT/PEEK composites with the MWCNTs modified with ethanolamine has been achieved and the self-lubricating film on their worn surfaces was also observed. - Highlights: • The dispersibility of surface modified MWCNTs in PEEK has been studied. • MWCNTs modified with ethanolamine have showed a good dispersion in PEEK. • Surface modifications of MWCNTs have a significant impact on both dynamic mechanical and tribological properties of MWCNT/PEEK composites. - Abstract: The effects of surface modifications of multi-walled carbon nanotubes (MWCNTs) on the morphology, dynamic mechanical and tribological properties of multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites have been investigated. MWCNTs were treated with mixed acids to obtain acid-functionalized MWCNTs. Then the acid-functionalized MWCNTs were modified with ethanolamine (named e-MWCNTs). The MWCNT/PEEK composites were prepared by a solution-blending method. A more homogeneous distribution of e-MWCNTs within the composites was found with scanning electron microscopy. Dynamic mechanical analysis demonstrated a clear increase in the storage modulus of e-MWCNT/PEEK composites because of the improved interfacial adhesion strength between e-MWCNTs and PEEK. Furthermore, the presence of e

  17. Plasma-activated multi-walled carbon nanotube-polystyrene composite substrates for biosensing

    International Nuclear Information System (INIS)

    Fernandez-Sanchez, Cesar; Orozco, Jahir; Jimenez-Jorquera, Cecilia; Pellicer, Eva; Lechuga, Laura M; Mendoza, Ernest

    2009-01-01

    Carbon nanotube-polymer composites have shown to be suitable materials for the fabrication of electrochemical transducers. The exposed surface of these materials is commonly passivated by a very thin layer of the polymer component that buries the conductive carbon particles. Working with multi-walled carbon nanotube-polystyrene (MWCNT-PS) composite structures, it was previously described how a simple low power oxygen plasma process produced an effective etching of the composite surface, thereby exposing the conductive surface of CNTs. This work shows how this plasma process not only gave rise to a suitable composite conductive surface for electrochemical sensing but simultaneously exposed and created a high density of oxygen-containing functional groups at both the CNT and the PS components, without affecting the material's mechanical stability. These chemical groups could be effectively modified for the stable immobilization of biological receptors. A detailed chemical characterization of the plasma-activated composite surface was possible using x-ray photoelectron spectroscopy. The material reactivity towards the tethering of a protein was studied and protein-protein interactions were then evaluated on the modified composite transducers by scanning electron microscopy. Finally, an amperometric immunosensor approach for the detection of rabbit Immunoglobulin G target analyte was described and a minimum concentration of 3 ng ml -1 was easily measured.

  18. Plasma-activated multi-walled carbon nanotube-polystyrene composite substrates for biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Sanchez, Cesar; Orozco, Jahir; Jimenez-Jorquera, Cecilia [Instituto de Microelectronica de Barcelona, IMB-CNM (CSIC), Campus UAB, E-08193 Bellaterra, Barcelona (Spain); Pellicer, Eva; Lechuga, Laura M; Mendoza, Ernest, E-mail: cesar.fernandez@imb-cnm.csic.e [Nanobiosensors and Molecular Nanobiophysics Group, Research Center on Nanoscience and Nanotechnology (CIN2) CSIC-ICN, ETSE, Campus UAB-Edificio Q, E-08193 Bellaterra, Barcelona (Spain)

    2009-08-19

    Carbon nanotube-polymer composites have shown to be suitable materials for the fabrication of electrochemical transducers. The exposed surface of these materials is commonly passivated by a very thin layer of the polymer component that buries the conductive carbon particles. Working with multi-walled carbon nanotube-polystyrene (MWCNT-PS) composite structures, it was previously described how a simple low power oxygen plasma process produced an effective etching of the composite surface, thereby exposing the conductive surface of CNTs. This work shows how this plasma process not only gave rise to a suitable composite conductive surface for electrochemical sensing but simultaneously exposed and created a high density of oxygen-containing functional groups at both the CNT and the PS components, without affecting the material's mechanical stability. These chemical groups could be effectively modified for the stable immobilization of biological receptors. A detailed chemical characterization of the plasma-activated composite surface was possible using x-ray photoelectron spectroscopy. The material reactivity towards the tethering of a protein was studied and protein-protein interactions were then evaluated on the modified composite transducers by scanning electron microscopy. Finally, an amperometric immunosensor approach for the detection of rabbit Immunoglobulin G target analyte was described and a minimum concentration of 3 ng ml{sup -1} was easily measured.

  19. ELECTROPHORETIC DEPOSITION OF TIO2-MULTI-WALLED CARBON NANOTUBE COMPOSITE COATINGS: MORPHOLOGICAL STUDY

    Directory of Open Access Journals (Sweden)

    M. S. MAHMOUDI JOZEE

    2016-09-01

    Full Text Available A homogenous TiO2 / multi-walled carbon nanotubes(MWCNTs composite film were prepared by electrophoretic co-deposition from organic suspension on a stainless steel substrate.  In this study, MWCNTs was incorporated to the coating because of their long structure and their capability to be functionalized by different inorganic groups on the surface. FTIR spectroscopy showed the existence of carboxylic groups on the modified carbon nanotubes surface. The effect of applied electrical fields, deposition time and concentration of nanoparticulates on coatings morphology were investigated by scanning electron microscopy. It was found that combination of MWCNTs within TiO2 matrix eliminating micro cracks presented on TiO2 coating. Also, by increasing the deposition voltages, micro cracks were increased. SEM observation of the coatings revealed that TiO2/multi-walled carbon nanotubes coatings produced from optimized electric field was uniform and had good adhesive to the substrate.

  20. Isolate-dependent growth, virulence, and cell wall composition in the human pathogen Aspergillus fumigatus.

    Directory of Open Access Journals (Sweden)

    Nansalmaa Amarsaikhan

    Full Text Available The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall β-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype.

  1. Lateral stiffness and vibration characteristics of composite plated RC shear walls with variable fibres spacing

    International Nuclear Information System (INIS)

    Meftah, S.A.; Yeghnem, R.; Tounsi, A.; Adda Bedia, E.A.

    2008-01-01

    In this paper, a finite element model for static and free vibration analysis of reinforced concrete (RC) shear walls structures strengthened with thin composite plates having variable fibres spacing is presented. An efficient analysis method that can be used regardless to the sizes and location of the bonded plates is proposed in this study. In the numerical formulation, the adherents and the adhesives are all modelled as shear wall elements, using the mixed finite element method. Several test problems are examined to demonstrate the accuracy and effectiveness of the proposed method. Numerical results are obtained for six nonuniform distributions of E-glass, graphite and boron fibres in epoxy matrices. The fibre redistributions of the bonded plates are seen to increase the frequencies modes and reduce substantially the lateral displacements

  2. Topochemical distribution of lignin and hydroxycinnamic acids in sugar-cane cell walls and its correlation with the enzymatic hydrolysis of polysaccharides

    Directory of Open Access Journals (Sweden)

    Koch Gerald

    2011-03-01

    Full Text Available Abstract Background Lignin and hemicelluloses are the major components limiting enzyme infiltration into cell walls. Determination of the topochemical distribution of lignin and aromatics in sugar cane might provide important data on the recalcitrance of specific cells. We used cellular ultraviolet (UV microspectrophotometry (UMSP to topochemically detect lignin and hydroxycinnamic acids in individual fiber, vessel and parenchyma cell walls of untreated and chlorite-treated sugar cane. Internodes, presenting typical vascular bundles and sucrose-storing parenchyma cells, were divided into rind and pith fractions. Results Vascular bundles were more abundant in the rind, whereas parenchyma cells predominated in the pith region. UV measurements of untreated fiber cell walls gave absorbance spectra typical of grass lignin, with a band at 278 nm and a pronounced shoulder at 315 nm, assigned to the presence of hydroxycinnamic acids linked to lignin and/or to arabino-methylglucurono-xylans. The cell walls of vessels had the highest level of lignification, followed by those of fibers and parenchyma. Pith parenchyma cell walls were characterized by very low absorbance values at 278 nm; however, a distinct peak at 315 nm indicated that pith parenchyma cells are not extensively lignified, but contain significant amounts of hydroxycinnamic acids. Cellular UV image profiles scanned with an absorbance intensity maximum of 278 nm identified the pattern of lignin distribution in the individual cell walls, with the highest concentration occurring in the middle lamella and cell corners. Chlorite treatment caused a rapid removal of hydroxycinnamic acids from parenchyma cell walls, whereas the thicker fiber cell walls were delignified only after a long treatment duration (4 hours. Untreated pith samples were promptly hydrolyzed by cellulases, reaching 63% of cellulose conversion after 72 hours of hydrolysis, whereas untreated rind samples achieved only 20

  3. Sensitization of the analytical methods for photoneutron calculations to the wall concrete composition in radiation therapy

    International Nuclear Information System (INIS)

    Ghiasi, Hosein; Mesbahi, Asghar

    2012-01-01

    The effect of wall material on photoneutron production in radiation therapy rooms was studied using Monte Carlo (MC) simulations. An analytical formula was proposed to take into account the concrete composition in photoneutron dose calculations. Using the MCNPX MC code, the 18 MV photon beam of the Varian Clinac 2100 and a typical treatment room with concrete compositions according to report No. 144 of National Council of Radiation Protection (NCRP) were simulated. Number of room produced photoneutrons per Gray of X-ray at the isocenter was determined for different types of concrete and named as “Q W ”. This new factor was inserted in the used formula for photoneutron fluence calculations at the inner entrance of maze. The photoneutron fluence was calculated using new proposed formula at the inner entrance of maze for all studied concretes. The difference between conventional and proposed equations varied from 11% to 46% for studied concretes. It was found that room produced photoneutrons could be significant for high density concretes. Additionally, applying the new proposed formula can consider the effect of wall material composition on the photoneutron production in high energy radiation therapy rooms. Further studies to confirm the accuracy of newly developed method is recommended.

  4. CURVED WALLS: GRAIN GROWTH, SETTLING, AND COMPOSITION PATTERNS IN T TAURI DISK DUST SUBLIMATION FRONTS

    Energy Technology Data Exchange (ETDEWEB)

    McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Building., Ann Arbor, MI 48109 (United States); D' Alessio, P. [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, 58089 Morelia, Michoacán (Mexico); Espaillat, C. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Sargent, B. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Hernández, J., E-mail: melisma@umich.edu, E-mail: ncalvet@umich.edu, E-mail: lhartm@umich.edu, E-mail: lingleby@umich.edu, E-mail: p.dalessio@astrosmo.unam.mx, E-mail: cespaillat@cfa.harvard.edu, E-mail: baspci@rit.edu, E-mail: dmw@pas.rochester.edu, E-mail: hernandj@cida.ve [Centro de Investigaciones de Astronomía (CIDA), Mérida 5101-A (Venezuela, Bolivarian Republic of)

    2013-10-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best fits to the near- and mid-IR excesses are found for curved, two-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe) = 0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10{sup –8} to 10{sup –10} M{sub ☉} yr{sup –1}, the maximum grain size in the lower layer decreases from ∼3 to 0.5 μm. We attribute this to a decrease in fragmentation and turbulent support for micron-sized grains with decreasing viscous heating. The atmosphere of these disks is depleted of dust with dust-gas mass ratios 1 × 10{sup –4} of the interstellar medium (ISM) value, while the midplane is enhanced to eight times the ISM value. For all accretion rates, the wall contributes at least half of the flux in the optically thin 10 μm silicate feature. Finally, we find evidence for an iron gradient in the disk, suggestive of that found in our solar system.

  5. CURVED WALLS: GRAIN GROWTH, SETTLING, AND COMPOSITION PATTERNS IN T TAURI DISK DUST SUBLIMATION FRONTS

    International Nuclear Information System (INIS)

    McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L.; D'Alessio, P.; Espaillat, C.; Sargent, B.; Watson, D. M.; Hernández, J.

    2013-01-01

    The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall properties for four classical T Tauri stars with a narrow range of spectral types and inclination angles and a wide range of mass accretion rates to determine the extent to which the walls are radially curved. Best fits to the near- and mid-IR excesses are found for curved, two-layer walls in which the lower layer contains larger, hotter, amorphous pyroxene grains with Mg/(Mg+Fe) = 0.6 and the upper layer contains submicron, cooler, mixed amorphous olivine and forsterite grains. As the mass accretion rates decrease from 10 –8 to 10 –10 M ☉ yr –1 , the maximum grain size in the lower layer decreases from ∼3 to 0.5 μm. We attribute this to a decrease in fragmentation and turbulent support for micron-sized grains with decreasing viscous heating. The atmosphere of these disks is depleted of dust with dust-gas mass ratios 1 × 10 –4 of the interstellar medium (ISM) value, while the midplane is enhanced to eight times the ISM value. For all accretion rates, the wall contributes at least half of the flux in the optically thin 10 μm silicate feature. Finally, we find evidence for an iron gradient in the disk, suggestive of that found in our solar system

  6. Flexural behavior and design of steel-plate composite (SC) walls for accident thermal loading

    Energy Technology Data Exchange (ETDEWEB)

    Booth, Peter N., E-mail: boothpn@purdue.edu [Lyles School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Varma, Amit H., E-mail: ahvarma@purdue.edu [Lyles School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Sener, Kadir C., E-mail: ksener@purdue.edu [Lyles School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Malushte, Sanjeev R. [Bechtel Corp., Frederick, MD (United States)

    2015-12-15

    Modular steel-plate composite (SC) safety-related nuclear power plant structures must be designed to resist accident thermal and mechanical loads. The design accident thermal load represents the condition where high pressure and temperature steam is released as result of a mechanical failure and applied against the surfaces of power plant structural walls. The effect of heating and pressure can have both short and long term effects on the mechanical integrity of SC structures including degradation and cracking of concrete infill, residual stresses, and out-of-plane deformations. The purpose of this research is to study the effects of thermal and mechanical loads on the out-of-plane flexural response of SC walls and to develop simplified equations that can be used to predict behavior. Four experimental beam tests are reported that represent full-scale cross-sections of SC walls subjected to combinations of mechanical and thermal loads. The study determined that thermal loads reduce the out-of-plane flexural stiffness of SC walls. For the ambient condition, the flexural stiffness closely matches a conventional elastic cracked-transformed model, and at elevated temperatures, the stiffness is reduced to a fully-cracked flexural stiffness that only takes into account the stiffness of the steel faceplates. A method is presented for estimating the thermal curvature, ϕ{sub th}, and thermal moment, M{sub th}, resulting from unequal heating of opposing faces of an SC wall. Based on the tests in this study, the application of accident thermal loads did not result in a reduction of the flexural strength of the SC section.

  7. Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

    Directory of Open Access Journals (Sweden)

    Pintu Kumar Mandal

    2014-01-01

    Full Text Available A straightforward convergent synthesis has been carried out for the tetrasaccharide repeating unit of the O-specific cell wall lipopolysaccharide of the strain Sp7 of Azospirillum brasilense. The target tetrasaccharide has been synthesized from suitably protected monosaccharide intermediates in 42% overall yield in seven steps by using a [2 + 2] block glycosylation approach.

  8. Modulation, functionality, and cytocompatibility of three-dimensional printing materials made from chitosan-based polysaccharide composites.

    Science.gov (United States)

    Wu, Chin-San

    2016-12-01

    The mechanical properties, cytocompatibility, and fabrication of three-dimensional (3D) printing strips of composite materials containing polylactide (PLA) and chitosan (CS) were evaluated. Maleic anhydride-grafted polylactide (PLA-g-MA) and CS were used to enhance the desired characteristics of these composites. The PLA-g-MA/CS materials exhibited better mechanical properties than the PLA/CS composites; this effect was attributed to a greater compatibility between the grafted polyester and CS. The water resistance of the PLA-g-MA/CS composites was greater than that of the PLA/CS composites; cytocompatibility evaluation with human foreskin fibroblasts (FBs) indicated that both materials were nontoxic. Moreover, CS enhanced the antibacterial activity properties of PLA-g-MA and PLA/CS composites. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Composition of Lycium barbarum polysaccharides and their apoptosis-inducing effect on human hepatoma SMMC-7721 cells

    Directory of Open Access Journals (Sweden)

    Qian Zhang

    2015-11-01

    Full Text Available Background: Lycium barbarum polysaccharide (LBP is a natural functional component that has a variety of biological activities. The molecular structures and apoptosis-inducing activities on human hepatoma SMMC-7721 cells of two LBP fractions, LBP-d and LBP-e, were investigated. Results: The results showed that LBP-d and LBP-e both consist of protein, uronic acid, and neutral sugars in different proportions. The structure of LBP was characterized by gas chromatography, periodate oxidation, and Smith degradation. LBP-d was composed of eight kinds of monosaccharides (fucose, ribose, rhamnose, arabinose, xylose, mannose, galactose, and glucose, while LBP-e was composed of six kinds of monosaccharides (fucose, rhamnose, arabinose, mannose, galactose, and glucose. LBP-d and LBP-e blocked SMMC-7721 cells at the G0/G1 and S phases with an inhibition ratio of 26.70 and 45.13%, respectively, and enhanced the concentration of Ca2 + in the cytoplasm of SMMC-7721. Conclusion: The contents of protein, uronic acid, and galactose in LBP-e were much higher than those in LBP-d, which might responsible for their different bioactivities. The results showed that LBP can be provided as a potential chemotherapeutic agent drug to treat cancer.

  10. Genetic complexity of miscanthus cell wall composition and biomass quality for biofuels.

    Science.gov (United States)

    van der Weijde, Tim; Kamei, Claire L Alvim; Severing, Edouard I; Torres, Andres F; Gomez, Leonardo D; Dolstra, Oene; Maliepaard, Chris A; McQueen-Mason, Simon J; Visser, Richard G F; Trindade, Luisa M

    2017-05-25

    Miscanthus sinensis is a high yielding perennial grass species with great potential as a bioenergy feedstock. One of the challenges that currently impedes commercial cellulosic biofuel production is the technical difficulty to efficiently convert lignocellulosic biomass into biofuel. The development of feedstocks with better biomass quality will improve conversion efficiency and the sustainability of the value-chain. Progress in the genetic improvement of biomass quality may be substantially expedited by the development of genetic markers associated to quality traits, which can be used in a marker-assisted selection program. To this end, a mapping population was developed by crossing two parents of contrasting cell wall composition. The performance of 182 F1 offspring individuals along with the parents was evaluated in a field trial with a randomized block design with three replicates. Plants were phenotyped for cell wall composition and conversion efficiency characters in the second and third growth season after establishment. A new SNP-based genetic map for M. sinensis was built using a genotyping-by-sequencing (GBS) approach, which resulted in 464 short-sequence uniparental markers that formed 16 linkage groups in the male map and 17 linkage groups in the female map. A total of 86 QTLs for a variety of biomass quality characteristics were identified, 20 of which were detected in both growth seasons. Twenty QTLs were directly associated to different conversion efficiency characters. Marker sequences were aligned to the sorghum reference genome to facilitate cross-species comparisons. Analyses revealed that for some traits previously identified QTLs in sorghum occurred in homologous regions on the same chromosome. In this work we report for the first time the genetic mapping of cell wall composition and bioconversion traits in the bioenergy crop miscanthus. These results are a first step towards the development of marker-assisted selection programs in miscanthus

  11. Effects of gas composition on the growth of multi-walled carbon nanotube

    International Nuclear Information System (INIS)

    Fang, T.-H.; Chang, W.-J.; Lu, D.-M.; Lien, W.-C.

    2007-01-01

    This paper studies the effects of different gas compositions on the growth of multi-walled carbon nanotube (MWCNT) films by using an electron cyclotron resonance chemical vapor deposition (ECR-CVD) method. The Raman spectrum was employed to explore the composition of the MWCNT films grown under different mixtures of C 3 H 8 and H 2 . The results showed that the optimum relative intensity ratio of the D band to G band (i.e., I D /I G ) is 2 for the cases considered in this study. In addition, the morphology and microstructure of the MWCNTs were examined by field emission scanning electron microscopy (FE-SEM) and field emission gun transmission electron microscopy (FEG-TEM). Furthermore, atomic force microscopy (AFM) and scanning thermal microscopy (SThM) were used to study the surface topography and thermal properties of the MWCNTs

  12. Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films

    Science.gov (United States)

    Ge, Jun; Cheng, Guanghui; Chen, Liwei

    2011-08-01

    Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 µg cm-2 and 59 wt% PANI gives a specific capacitance of 55.0 F g-1 at a current density of 2.6 A g-1, showing its possibility for transparent and flexible energy storage.

  13. Heat and mass transfer in a liquid pool with wall ablation and composition effects

    International Nuclear Information System (INIS)

    Pham, Q.T.

    2013-01-01

    This work deals with the thermal-hydraulics of a melt pool coupled with the physical chemistry for the purpose of describing the behaviour of mixtures of materials (non-eutectic). Evolution of transient temperature in a liquid melt pool heated by volumetric power dissipation has been described with solidification on the cooled wall. The model has been developed and is validated for the experimental results given by LIVE experiment, performed at Karlsruhe Institute of Technology (KIT) in Germany. Under the conditions of these tests, it is shown that the interface temperature follows the liquidus temperature (corresponding to the composition of the liquid bath) during the whole transient. Assumption of interface temperature as liquidus temperature allows recalculating the evolution of the maximum melt temperature as well as the local crust thickness. Furthermore, we propose a model for describing the interaction between a non-eutectic liquid melt pool (subjected to volumetric power dissipation) and an ablated wall whose melting point is below the liquidus temperature of the melt. The model predictions are compared with results of ARTEMIS 2D tests. A new formulation of the interface temperature between the liquid melt and the solid wall (below liquidus temperature) has been proposed. (author) [fr

  14. Characterization of diferuloylated pectic polysaccharides from quinoa (Chenopodium quinoa WILLD.).

    Science.gov (United States)

    Wefers, Daniel; Gmeiner, Bianca M; Tyl, Catrin E; Bunzel, Mirko

    2015-08-01

    In plants belonging to the order of Caryophyllales, pectic neutral side chains can be substituted with ferulic acid. The ability of ferulic acid to form intra- and/or intermolecular polysaccharide cross-links by dimerization was shown by the isolation and characterization of diferulic acid oligosaccharides from monocotyledonous plants. In this study, two diferulic acid oligosaccharides were isolated from the enzymatic hydrolyzate of seeds of the dicotyledonous pseudocereal quinoa by gel permeation chromatography and preparative HPLC and unambiguously identified by LC-MS(2) and 1D/2D NMR spectroscopy. The isolated oligosaccharides are comprised of 5-5- and 8-O-4-diferulic acid linked to the O2-position of the nonreducing residue of two (1→5)-linked arabinobioses. To get insight into the structure and the degree of phenolic acid substitution of the diferuloylated polysaccharides, polymeric sugar composition, glycosidic linkages, and polysaccharide-bound monomeric phenolic acids and diferulic acids were analyzed. This study demonstrates that diferulic acids are involved into intramolecular and/or intermolecular cross-linking of arabinan chains and may have a major impact on cell wall architecture of quinoa and other dicotyledonous plants of the order of Caryophyllales. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. The microwave absorbing properties of SmCo attached single wall carbon nanotube/epoxy composites

    International Nuclear Information System (INIS)

    Yu, Liming; Li, Bo; Sheng, Leimei; An, Kang; Zhao, Xinluo

    2013-01-01

    Highlights: •The SmCo nanoparticles attached SWCNTs were prepared by dc arc discharge method. •The nano-composite prepared by a rare earth permanent magnet Sm 2 Co 17 as catalyst. •The SmCo attached SWCNT/epoxy composites have an excellent electromagnetic matching characteristics. •The reflection loss and bandwidth below −20 dB of the composite can reach −23.7 dB, 6.2 GHz, respectively. -- Abstract: The SmCo nanoparticles attached single wall carbon nanotubes (SmCo attached SWCNTs) were prepared by hydrogen dc arc discharge method using 2:17 type SmCo permanent powder as catalyst. The SmCo attached SWCNT/epoxy composites with different doping ratios were investigated in the frequency region of 2–18 GHz. The complex permittivity and permeability of the SmCo attached SWCNT/epoxy composites were calculated. The reflection loss properties were simulated by transmission line theory and the microwave absorptive mechanisms were discussed. The results indicate that, due to the better interfacial polarization absorption mechanism of SmCo attached SWCNTs and the electromagnetic (EM) matching of magnetic loss and dielectric loss, the microwave absorption properties of SmCo attached SWCNT/epoxy are evidently improved. When the SmCo attached SWCNTs is doped by 1 wt%, the composite display a larger and wider absorption peak, and the bandwidth of the reflection loss below −20 dB is larger than 6 GHz with the thickness of 3.3 mm. It is expected that the new SmCo attached SWCNT/epoxy composites will be a good microwave absorbing material for the applications in X band, Ku band, or even K band

  16. Lignin monomer composition affects Arabidopsis cell-wall degradability after liquid hot water pretreatment

    Directory of Open Access Journals (Sweden)

    Ladisch Michael

    2010-12-01

    Full Text Available Abstract Background Lignin is embedded in the plant cell wall matrix, and impedes the enzymatic saccharification of lignocellulosic feedstocks. To investigate whether enzymatic digestibility of cell wall materials can be improved by altering the relative abundance of the two major lignin monomers, guaiacyl (G and syringyl (S subunits, we compared the degradability of cell wall material from wild-type Arabidopsis thaliana with a mutant line and a genetically modified line, the lignins of which are enriched in G and S subunits, respectively. Results Arabidopsis tissue containing G- and S-rich lignins had the same saccharification performance as the wild type when subjected to enzyme hydrolysis without pretreatment. After a 24-hour incubation period, less than 30% of the total glucan was hydrolyzed. By contrast, when liquid hot water (LHW pretreatment was included before enzyme hydrolysis, the S-lignin-rich tissue gave a much higher glucose yield than either the wild-type or G-lignin-rich tissue. Applying a hot-water washing step after the pretreatment did not lead to a further increase in final glucose yield, but the initial hydrolytic rate was doubled. Conclusions Our analyses using the model plant A. thaliana revealed that lignin composition affects the enzymatic digestibility of LHW pretreated plant material. Pretreatment is more effective in enhancing the saccharification of A. thaliana cell walls that contain S-rich lignin. Increasing lignin S monomer content through genetic engineering may be a promising approach to increase the efficiency and reduce the cost of biomass to biofuel conversion.

  17. WATER VAPOUR PERMEABILITY PROPERTIES OF CELLULAR WOOD MATERIAL AND CONDENSATION RISK OF COMPOSITE PANEL WALLS

    Directory of Open Access Journals (Sweden)

    Janis IEJAVS

    2016-09-01

    Full Text Available Invention of light weight cellular wood material (CWM with a trade mark of Dendrolight is one of innovations in wood industry of the last decade. The aim of the research was to define the water vapour permeability properties of CWM and to analyse the condensation risk of various wall envelopes where solid wood cellular material is used. To determine the water vapour permeability of CWM, test samples were produced in the factory using routine production technology and tested according to the standard EN 12086:2014. Water vapour permeability factor (μ and other properties of six different configurations of CWM samples were determined. Using the experimental data the indicative influence of geometrical parameters such as lamella thickness, number of lamellas and material direction were investigated and evaluated. To study the condensation risk within the wall envelope containing CWM calculation method given in LVS EN ISO 13788:2012 was used. To ease the calculation process previously developed JavaScript calculation software that had only capability to calculate thermal transmittance was extended so that condensation risk in multi-layer composite walls can be analysed. Water vapour permeability factor in CWM is highly direction dependant. If parallel and perpendicular direction of CWM is compared the value of water vapour permeability factor can differentiate more than two times. Another significant factor for condensation risk analysis is overall thickness of CWM since it directly influences the equivalent air layer thickness. The influence of other factors such as lamella thickness, or groove depth is minor when water vapour permeability properties are compared. From the analysis of CWM performance in building envelope it can be concluded that uninsulated CWM panels used during winter months will pose the risk of condensation damage to structure, but the risk can be reduced or prevented if insulation layer is applied to the CWM panel wall

  18. Insights into cell wall structure of Sida hermaphrodita and its influence on recalcitrance.

    Science.gov (United States)

    Damm, Tatjana; Pattathil, Sivakumar; Günl, Markus; Jablonowski, Nicolai David; O'Neill, Malcolm; Grün, Katharina Susanne; Grande, Philipp Michael; Leitner, Walter; Schurr, Ulrich; Usadel, Björn; Klose, Holger

    2017-07-15

    The perennial plant Sida hermaphrodita (Sida) is attracting attention as potential energy crop. Here, the first detailed view on non-cellulosic Sida cell wall polysaccharide composition, structure and architecture is given. Cell walls were prepared from Sida stems and sequentially extracted with aqueous buffers and alkali. The structures of the quantitatively predominant polysaccharides present in each fraction were determined by biochemical characterization, glycome profiling and mass spectrometry. The amounts of glucose released by Accellerase-1500 ® treatment of the cell wall and the cell wall residue remaining after each extraction were used to assess the roles of pectin and hemicellulose in the recalcitrance of Sida biomass. 4-O-Methyl glucuronoxylan with a low proportion of side substitutions was identified as the major non-cellulosic glycan component of Sida stem cell walls. Pectic polysaccharides and xylans were found to be associated with lignin, suggesting that these polysaccharides have roles in Sida cell wall recalcitrance to enzymatic hydrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. THERMAL DECOMPOSITION AND FLAMMABILITY OF ACRYLONITRILE-BUTADIENE-STYRENE/MULTI-WALLED CARBON NANOTUBES COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Li-fang Tong; Hai-yun Ma; Zheng-ping Fang

    2008-01-01

    Thermal and flammability properties of acrylonitrile-butadiene-styrene copolymer (ABS) with the addition of multi-walled carbon nanotubes (MWNTs) were studied. ABS/MWNTs composites were prepared via melt blending with the MWNTs content varied from 0.2% to 4.0% by mass. Thermogravimetry results showed that the addition of MWNTs accelerated the degradation of ABS during the whole process under air atmosphere, and both onset and maximum degradation temperature were lower than those of pure ABS. The destabilization effect of MWNTs on the thermal stability of the composites became unobvious under nitrogen, and the addition of MWNTs could improve the maximum degradation temperature. The heat release rate and time of ignition (tign) for the composites reduced greatly with the addition of MWNTs especially when the concentration of nanotubes was higher than 1.0%. The accumulation of carbon nanotubes with a network structure was observed and the char layer became thicker with increasing nanotubes concentration. Results from Raman spectra showed a higher degree of graphitization for the residues of ABS/MWNTs composites.

  20. Electrospun single-walled carbon nanotube/polyvinyl alcohol composite nanofibers: structure-property relationships

    International Nuclear Information System (INIS)

    Naebe, Minoo; Lin Tong; Wang Xungai; Staiger, Mark P; Dai Liming

    2008-01-01

    Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde

  1. Preparation and characterization of bagasse/HDPE composites using multi-walled carbon nanotubes.

    Science.gov (United States)

    Ashori, Alireza; Sheshmani, Shabnam; Farhani, Foad

    2013-01-30

    This article presents the preparation and characterization of bagasse/high density polyethylene (HDPE) composites. The effects of multi-walled carbon nanotubes (MWCNTs), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. In the sample preparation, MWCNTs and MAPE contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results of strength measurement indicated that when 1.5 wt% MWCNTs were added, tensile and flexural properties reached their maximum values. At high level of MWCNTs loading (3 or 4 wt%), increased population of MWCNTs lead to agglomeration and stress transfer gets blocked. The addition of MWCNTs filler slightly decreased the impact strength of composites. Both mechanical and physical properties were improved when 4 wt% MAPE was applied. SEM micrographs also showed that the surface roughness improved with increasing MAPE loading from 0 to 4 wt%. The improvement of physicomechanical properties of composites confirmed that MWCNTs have good reinforcement and the optimum synergistic effect of MWCNTs and MAPE was achieved at the combination of 1.5 and 4 wt%, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction

    Directory of Open Access Journals (Sweden)

    Insub Choi

    2015-03-01

    Full Text Available A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

  3. Biochemical Aspects of Non-Starch Polysaccharides

    Directory of Open Access Journals (Sweden)

    Rodica Căpriţă

    2010-05-01

    Full Text Available Polysaccharides are macromolecules of monosaccharides linked by glycosidic bonds. Non-starch polysaccharides (NSP are principally non-α-glucan polysaccharides of the plant cell wall. They are a heterogeneous group of polysaccharides with varying degrees of water solubility, size, and structure. The water insoluble fiber fraction include cellulose, galactomannans, xylans, xyloglucans, and lignin, while the water-soluble fibers are the pectins, arabinogalactans, arabinoxylans, and β-(1,3(1,4-D-glucans (β-glucans. Knowledge of the chemical structure of NSP has permitted the development of enzyme technology to overcome their antinutritional effects. The physiological effects of NSP on the digestion and absorption of nutrients in human and monogastric animals have been attributed to their physicochemical properties: hydration properties, viscosity, cation exchange capacity and organic compound absorptive properties. This paper reviews and presents information on NSPs chemistry, physicochemical properties and physiological effects on the nutrient entrapment.

  4. Cell wall composition profiling of parasitic giant dodder (Cuscuta reflexa) and its hosts: a priori differences and induced changes.

    Science.gov (United States)

    Johnsen, Hanne R; Striberny, Bernd; Olsen, Stian; Vidal-Melgosa, Silvia; Fangel, Jonatan U; Willats, William G T; Rose, Jocelyn K C; Krause, Kirsten

    2015-08-01

    Host plant penetration is the gateway to survival for holoparasitic Cuscuta and requires host cell wall degradation. Compositional differences of cell walls may explain why some hosts are amenable to such degradation while others can resist infection. Antibody-based techniques for comprehensive profiling of cell wall epitopes and cell wall-modifying enzymes were applied to several susceptible hosts and a resistant host of Cuscuta reflexa and to the parasite itself. Infected tissue of Pelargonium zonale contained high concentrations of de-esterified homogalacturonans in the cell walls, particularly adjacent to the parasite's haustoria. High pectinolytic activity in haustorial extracts and high expression levels of pectate lyase genes suggest that the parasite contributes directly to wall remodeling. Mannan and xylan concentrations were low in P. zonale and in five susceptible tomato introgression lines, but high in the resistant Solanum lycopersicum cv M82, and in C. reflexa itself. Knowledge of the composition of resistant host cell walls and the parasite's own cell walls is useful in developing strategies to prevent infection by parasitic plants. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  5. Cytochemical Localization of Polysaccharides in Dendrobium officinale and the Involvement of DoCSLA6 in the Synthesis of Mannan Polysaccharides

    OpenAIRE

    He, Chunmei; Wu, Kunlin; Zhang, Jianxia; Liu, Xuncheng; Zeng, Songjun; Yu, Zhenming; Zhang, Xinghua; Teixeira da Silva, Jaime A.; Deng, Rufang; Tan, Jianwen; Luo, Jianping; Duan, Jun

    2017-01-01

    Dendrobium officinale is a precious traditional Chinese medicinal plant because of its abundant polysaccharides found in stems. We determined the composition of water-soluble polysaccharides and starch content in D. officinale stems. The extracted water-soluble polysaccharide content was as high as 35% (w/w). Analysis of the composition of monosaccharides showed that the water-soluble polysaccharides were dominated by mannose, to a lesser extent glucose, and a small amount of galactose, in a ...

  6. Comparison of consecutive harvests versus blending treatments to produce lower alcohol wines from Cabernet Sauvignon grapes: Impact on polysaccharide and tannin content and composition.

    Science.gov (United States)

    Schelezki, Olaf J; Smith, Paul A; Hranilovic, Ana; Bindon, Keren A; Jeffery, David W

    2018-04-01

    A changing climate has led to winegrapes being harvested with increased sugar levels and at greater risk of berry shrivel. A suggested easy-to-adopt strategy to manage the associated rising wine alcohol levels is the pre-fermentative substitution of juice with either "green harvest wine" or water. Our study investigates the effects of this approach on Vitis vinifera L. cv. Cabernet Sauvignon wine quality attributes. Wines were also made from fruit collected at consecutive earlier harvest time points to produce wines comparable in alcohol to the substituted wines. Tannin concentrations and colour did not change significantly in the wines with modified alcohol content even at higher juice substitution rates. Differences in polysaccharide and tannin composition indicated variability in extraction dynamics according to substitution rate and type of blending component. In scenarios where berry shrivel is inevitable, the incorporation of water in particular offers much promise as part of a strategy to manage wine alcohol content. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Current concepts and systematic review of vascularized composite allotransplantation of the abdominal wall.

    Science.gov (United States)

    Berli, Jens U; Broyles, Justin M; Lough, Denver; Shridharani, Sachin M; Rochlin, Danielle; Cooney, Damon S; Lee, W P Andrew; Brandacher, Gerald; Sacks, Justin M

    2013-01-01

    Abdominal wall vascularized composite allotransplantation (AW-VCA) is a rarely utilized technique for large composite abdominal wall defects. The goal of this article is to systematically review the literature and current concepts of AW-VCA, outline the challenges ahead, and provide an outlook for the future. Systematic review of the literature was performed using MEDLINE, EMBASE, and PubMed to identify relevant articles discussing results of AW-VCA. Cadaver and animal studies were excluded from the systematic review, but selectively included in the discussion. The resultant five papers report their results on AW-VCA(Transplantation, 85, 2008, 1607; Am J Transplant, 7, 2007, 1304; Transplant Proc, 41, 2009, 521; Transplant Proc, 36, 2004, 1561; Lancet, 361, 2003, 2173). These papers represent the result of two study groups in which a total of 18 AW-VCA were performed in 17 patients. Two different operative approaches were used. Overall flap/graft survival was 88%. No mortality related to the transplant was reported. One cadaver study and two animal models were identified and separately presented (Transplant Proc, 43, 2011, 1701; Transplantation, 90, 2010, 1590; Journal of Surgical Research, 162, 2010, 314). Literature review reports AW-VCA is technically feasible with low morbidity and mortality. Functional outcomes are not reported and minimally considered. With advancements in vascularized composite allotransplantation research and decreasing toxicity of immunosuppression therapies and immunomodulatory regimens, AW-VCA can be applied in circumstances beyond conjunction with visceral transplantation. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Parameter Sensitivity Analysis on Deformation of Composite Soil-Nailed Wall Using Artificial Neural Networks and Orthogonal Experiment

    Directory of Open Access Journals (Sweden)

    Jianbin Hao

    2014-01-01

    Full Text Available Based on the back-propagation algorithm of artificial neural networks (ANNs, this paper establishes an intelligent model, which is used to predict the maximum lateral displacement of composite soil-nailed wall. Some parameters, such as soil cohesive strength, soil friction angle, prestress of anchor cable, soil-nail spacing, soil-nail diameter, soil-nail length, and other factors, are considered in the model. Combined with the in situ test data of composite soil-nail wall reinforcement engineering, the network is trained and the errors are analyzed. Thus it is demonstrated that the method is applicable and feasible in predicting lateral displacement of excavation retained by composite soil-nailed wall. Extended calculations are conducted by using the well-trained intelligent forecast model. Through application of orthogonal table test theory, 25 sets of tests are designed to analyze the sensitivity of factors affecting the maximum lateral displacement of composite soil-nailing wall. The results show that the sensitivity of factors affecting the maximum lateral displacement of composite soil nailing wall, in a descending order, are prestress of anchor cable, soil friction angle, soil cohesion strength, soil-nail spacing, soil-nail length, and soil-nail diameter. The results can provide important reference for the same reinforcement engineering.

  9. Experimental, numerical, and analytical studies on the seismic response of steel-plate concrete (SC) composite shear walls

    Science.gov (United States)

    Epackachi, Siamak

    The seismic performance of rectangular steel-plate concrete (SC) composite shear walls is assessed for application to buildings and mission-critical infrastructure. The SC walls considered in this study were composed of two steel faceplates and infill concrete. The steel faceplates were connected together and to the infill concrete using tie rods and headed studs, respectively. The research focused on the in-plane behavior of flexure- and flexure-shear-critical SC walls. An experimental program was executed in the NEES laboratory at the University at Buffalo and was followed by numerical and analytical studies. In the experimental program, four large-size specimens were tested under displacement-controlled cyclic loading. The design variables considered in the testing program included wall thickness, reinforcement ratio, and slenderness ratio. The aspect ratio (height-to-length) of the four walls was 1.0. Each SC wall was installed on top of a re-usable foundation block. A bolted baseplate to RC foundation connection was used for all four walls. The walls were identified to be flexure- and flexure-shear critical. The progression of damage in the four walls was identical, namely, cracking and crushing of the infill concrete at the toes of the walls, outward buckling and yielding of the steel faceplates near the base of the wall, and tearing of the faceplates at their junctions with the baseplate. A robust finite element model was developed in LS-DYNA for nonlinear cyclic analysis of the flexure- and flexure-shear-critical SC walls. The DYNA model was validated using the results of the cyclic tests of the four SC walls. The validated and benchmarked models were then used to conduct a parametric study, which investigated the effects of wall aspect ratio, reinforcement ratio, wall thickness, and uniaxial concrete compressive strength on the in-plane response of SC walls. Simplified analytical models, suitable for preliminary analysis and design of SC walls, were

  10. Fiber and nonstarch polysaccharide content and variation in common crops used in broiler diets

    DEFF Research Database (Denmark)

    Knudsen, Knud Erik Bach

    2014-01-01

    The current paper reviews content and variation in fiber and nonstarch polysaccharides (NSP) of common crops used in broiler diets. The cereal grain is a complex structure, and its cell walls (CW) differ in their composition and hence properties. Arabinoxylan (AX), mixed linkage (1→3; 1→4)-β...... AX, but β-glucan can also be present mainly in rye and wheat brans. The CW composition of seeds and grains of protein crops and feedstuffs are different from that of cereals. The main CW polymers are pectic substances (homogalacturonan, rhamnogalacturonan type I and II, xylogalacturonan...

  11. Polysaccharides from Extremophilic Microorganisms

    Science.gov (United States)

    Nicolaus, B.; Moriello, V. Schiano; Lama, L.; Poli, A.; Gambacorta, A.

    2004-02-01

    Several marine thermophilic strains were analyzed for exopolysaccharide production. The screening process revealed that a significant number of thermophilic microorganisms were able to produce biopolymers, and some of them also revealed interesting chemical compositions. We have identified four new polysaccharides from thermophilic marine bacteria, with complex primary structures and with different repetitive units: a galacto-mannane type from strain number 4004 and mannane type for the other strains. The thermophilic Bacillus thermantarcticus produces two exocellular polysaccharides (EPS 1, EPS 2) that give the colonies a typical mucous character. The exopolysaccharide fraction was produced with all substrates assayed, although a higher yield 400 mg liter-1 was obtained with mannose as carbon and energy source. NMR spectra confirmed that EPS 1 was a heteropolysaccharide of which the repeating unit was constituted by four different α-D-mannoses and three different β-D-glucoses. It seems to be close to some xantan polymers. EPS 2 was a mannan. Four different α-D-mannoses were found as the repeating unit. Production and chemical studies of biopolymers produced by halophilic archaea, Haloarcula species were also reported.

  12. Cell-wall architecture and lignin composition of wheat developed in a microgravity environment

    Science.gov (United States)

    Levine, L. H.; Heyenga, A. G.; Levine, H. G.; Choi, J.; Davin, L. B.; Krikorian, A. D.; Lewis, N. G.; Sager, J. C. (Principal Investigator)

    2001-01-01

    The microgravity environment encountered during space-flight has long been considered to affect plant growth and developmental processes, including cell wall biopolymer composition and content. As a prelude to studying how microgravity is perceived - and acted upon - by plants, it was first instructive to investigate what gross effects on plant growth and development occurred in microgravity. Thus, wheat seedlings were exposed to microgravity on board the space shuttle Discovery (STS-51) for a 10 day duration, and these specimens were compared with their counterparts grown on Earth under the same conditions (e.g. controls). First, the primary roots of the wheat that developed under both microgravity and 1 g on Earth were examined to assess the role of gravity on cellulose microfibril (CMF) organization and secondary wall thickening patterns. Using a quick freeze/deep etch technique, this revealed that the cell wall CMFs of the space-grown wheat maintained the same organization as their 1 g-grown counterparts. That is, in all instances, CMFs were randomly interwoven with each other in the outermost layers (farthest removed from the plasma membrane), and parallel to each other within the individual strata immediately adjacent to the plasma membranes. The CMF angle in the innermost stratum relative to the immediately adjacent stratum was ca 80 degrees in both the space and Earth-grown plants. Second, all plants grown in microgravity had roots that grew downwards into the agar; they did not display "wandering" and upward growth as previously reported by others. Third, the space-grown wheat also developed normal protoxylem and metaxylem vessel elements with secondary thickening patterns ranging from spiral to regular pit to reticulate thickenings. Fourthly, both the space- and Earth-grown plants were essentially of the same size and height, and their lignin analyses revealed no substantial differences in their amounts and composition regardless of the gravitational

  13. Composition and Antitumor Activity of Polysaccharides from Sarcodon imbricatus%黑虎掌菌多糖的组成和抗肿瘤活性

    Institute of Scientific and Technical Information of China (English)

    陈健; 张灵芝; 韦丁; 徐晓飞

    2011-01-01

    Two kinds of polysaccharides, namely SIPa and SIPb, were obtained from the fruit body of Sarcodon im-bricatus via isolation and purification. Then, the IR spectra of the products were investigated, and the relative molecular mass and monosaccharide composition of each product were determined by means of high-performance gel permeation chromatography and gas chromatography. Moreover, the antitumor activities of the two products were evaluated by means of the MTT method. The results show that (1) SIPa and SIPb both possess typical infrared absorptions of polysaccharides; (2) the sugar chain of SIPa is mainly β-configuration pyranoside; (3) the weight-average relative molecular mass of SIPa and SIPb are respectively 2. 12 × 105 and 1. 05 × 104; (4) SIPa is a kind of glucan while SIPb is a kind of heteroglycan containing fucose, mannose, glucose and galactose in a molar ratio of 8. 93:1:4. 25:29. 18; and (5) both SIPa and SIPb remarkably inhibit the growth of human liver cancer cell line Hep G2 and human ovarian cancer cell line HO-8910 in a dose-dependent manner.%从黑虎掌菌的子实体中分离纯化得到两种多糖SIPa和SIPb,考察了它们的红外光谱特征,通过高效凝胶渗透色谱法和气相色谱法测定其相对分子质量和单糖组成,用MTT比色法进行抗肿瘤活性评价.结果表明:SIPa和SIPb都具有典型的多糖红外吸收,SIPa的糖链以β型吡喃糖苷为主;SIPa和SIPb的重均相对分子质量分别为2.12×105和1.05×104;SIPa是一种葡聚糖,SIPb是一种杂多糖,含有岩藻糖、甘露糖、葡萄糖和半乳糖,摩尔比为8.93:1:4.25:29.18;SIPa和SIPb对人肝癌细胞Hep G2和人卵巢癌细胞HO-8910都具有明显的抑制作用,且呈剂量依赖性.

  14. Study of the surface chemistry and morphology of single walled carbon nanotube-magnetite composites

    International Nuclear Information System (INIS)

    Marquez-Linares, F.; Uwakweh, O.N.C.; Lopez, N.; Chavez, E.; Polanco, R.; Morant, C.; Sanz, J.M.; Elizalde, E.; Neira, C.; Nieto, S.; Roque-Malherbe, R.

    2011-01-01

    The study of the morphologies of the single walled carbon nanotube (SWCNT), magnetite nanoparticles (MNP), and the composite based on them was carried with combined X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). These techniques together with thermogravimetric analyses (TGA) and diffuse reflectance infrared transform spectroscopy (DRIFTS) confirmed the production of pure single phases, and that the composite material consisted of MNP attached to the outer surface of the SWCNT. The Moessbauer spectroscopy (MS) research showed the presence of a large quantity of Lewis acid sites in the highly dispersed magnetite particles supported on the SWCNT outer surface. The DRIFTS carbon dioxide adsorption study of the composites revealed significant adsorption of carbon dioxide, fundamentally in the Lewis acid sites. Then, the Lewis acid sites were observed to be catalytically active. Further, the electron exchange between the Lewis acid sites and the basic or amphoteric adsorbed molecules could influence the magnetic properties of the magnetite. Consequently, together with this first ever use of MS in the study of Lewis acid sites, this investigation revealed the potential of the composites for catalytic and sensors applications. -- Graphical abstract: A large amount of Lewis acid sites were found in the highly dispersed magnetite which is supported on the SWCNT outer surface. Display Omitted Research highlights: → The obtained materials were completely characterized with XRD, Raman and SEM-TEM. → DRIFT, TGA and adsorption of the composites allowed understand the material formation. → This is the first report of a study of Lewis sites by Moessbauer spectroscopy.

  15. Electrical resistivity and thermal properties of compatibilized multi-walled carbon nanotube/polypropylene composites

    Directory of Open Access Journals (Sweden)

    A. Szentes

    2012-06-01

    Full Text Available The electrical resistivity and thermal properties of multi-walled carbon nanotube/polypropylene (MWCNT/PP composites have been investigated in the presence of coupling agents applied for improving the compatibility between the nanotubes and the polymer. A novel olefin-maleic-anhydride copolymer and an olefin-maleic-anhydride copolymer based derivative have been used as compatibilizers to achieve better dispersion of MWCNTs in the polymer matrix. The composites have been produced by extrusion followed by injection moulding. They contained different amounts of MWCNTs (0.5, 2, 3 and 5 wt% and coupling agent to enhance the interactions between the carbon nanotubes and the polymer. The electrical resistivity of the composites has been investigated by impedance spectroscopy, whereas their thermal properties have been determined using a thermal analyzer operating on the basis of the periodic thermal perturbation method. Rheological properties, BET-area and adsorption-desorption isotherms have been determined. Dispersion of MWCNTs in the polymer has been studied by scanning electron microscopy (SEM.

  16. Strain-dependent electrical resistance of multi-walled carbon nanotube/polymer composite films

    International Nuclear Information System (INIS)

    Park, Myounggu; Kim, Hyonny; Youngblood, Jeffrey P

    2008-01-01

    The strain-dependent electrical resistance characteristics of multi-walled carbon nanotube (MWCNT)/polymer composite films were investigated. In this research, polyethylene oxide (PEO) is used as the polymer matrix. Two representative volume fractions of MWCNT/PEO composite films were selected: 0.56 vol% (near the percolation threshold) and 1.44 vol% (away from the percolation threshold) of MWCNT. An experimental setup which can measure electrical resistance and strain simultaneously and continuously has been developed. Unique and repeatable relationships in resistance versus strain were obtained for multiple specimens with different volume fractions of MWCNT. The overall pattern of electrical resistance change versus strain for the specimens tested consists of linear and nonlinear regions. A resistance change model to describe the combination of linear and nonlinear modes of electrical resistance change as a function of strain is suggested. The unique characteristics in electrical resistance change for different volume fractions imply that MWCNT/PEO composite films can be used as tunable strain sensors and for application into embedded sensor systems in structures

  17. Aligned multi-walled carbon nanotube-reinforced composites: processing and mechanical characterization

    International Nuclear Information System (INIS)

    Thostenson, Erik T.; Chou, Tsuwei

    2002-01-01

    Carbon nanotubes have been the subject of considerable attention because of their exceptional physical and mechanical properties. These properties observed at the nanoscale have motivated researchers to utilize carbon nanotubes as reinforcement in composite materials. In this research, a micro-scale twin-screw extruder was used to achieve dispersion of multi-walled carbon nanotubes in a polystyrene matrix. Highly aligned nanocomposite films were produced by extruding the polymer melt through a rectangular die and drawing the film prior to cooling. Randomly oriented nanocomposites were produced by achieving dispersion first with the twin-screw extruder followed by pressing a film using a hydraulic press. The tensile behaviour of the aligned and random nanocomposite films with 5 wt.{%} loading of nanotubes were characterized. Addition of nanotubes increased the tensile modulus, yield strength and ultimate strengths of the polymer films, and the improvement in elastic modulus with the aligned nanotube composite is five times greater than the improvement for the randomly oriented composite. (author)

  18. Infrared and microwave properties of polypyrrole/multi-walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Qi; Wang, Yongsheng, E-mail: yshwang@bjtu.edu.cn; He, Dawei, E-mail: dwhe@bjtu.edu.cn; Gao, Lei; Zhou, Yikang; Fu, Ming

    2014-08-01

    This study analyses the formation of polypyrrole/multi-walled carbon nanotube (PPy/MWCNT) composite materials using chemical oxidation with varying amounts of MWCNTs added. The samples are characterized by scanning electron microscopy, Fourier transform infrared emission spectroscopy, a four-probe method, and infrared thermal imaging using electromagnetic parameters. According to the test results, it is seen that the formation of PPy with the addition of MWCNTs can affect the material’s infrared properties and increase the material’s microwave return losses (up to −19 dB). This production procedure can also make the peak frequency of the microwave return losses adjustable, and the composite’s infrared and microwave performance becomes compatible and adjustable. - Highlights: • A one step in-situ synthesis method of PPy/MWCNT polymerization is proposed. • The composites were used for infrared camouflage and for their microwave properties. • The microwave return losses and infrared emissivity of the composites are adjustable. • The mechanism relies on changes in the composites’ conductivity.

  19. Infrared and microwave properties of polypyrrole/multi-walled carbon nanotube composites

    International Nuclear Information System (INIS)

    Gao, Qi; Wang, Yongsheng; He, Dawei; Gao, Lei; Zhou, Yikang; Fu, Ming

    2014-01-01

    This study analyses the formation of polypyrrole/multi-walled carbon nanotube (PPy/MWCNT) composite materials using chemical oxidation with varying amounts of MWCNTs added. The samples are characterized by scanning electron microscopy, Fourier transform infrared emission spectroscopy, a four-probe method, and infrared thermal imaging using electromagnetic parameters. According to the test results, it is seen that the formation of PPy with the addition of MWCNTs can affect the material’s infrared properties and increase the material’s microwave return losses (up to −19 dB). This production procedure can also make the peak frequency of the microwave return losses adjustable, and the composite’s infrared and microwave performance becomes compatible and adjustable. - Highlights: • A one step in-situ synthesis method of PPy/MWCNT polymerization is proposed. • The composites were used for infrared camouflage and for their microwave properties. • The microwave return losses and infrared emissivity of the composites are adjustable. • The mechanism relies on changes in the composites’ conductivity

  20. Adsorption of Cadmium Ions from Water on Double-walled Carbon Nanotubes/Iron Oxide Composite

    Directory of Open Access Journals (Sweden)

    Karima Seffah

    2017-12-01

    Full Text Available A new material (DWCNT/iron oxide for heavy metals removal was developed by combining the adsorption features of double-walled carbon nanotubes with the magnetic properties of iron oxides. Batch experiments were applied in order to evaluate adsorption capacity of the DWCNT/iron oxide composite for cadmium ions. The influence of operating parameters such as pH value, amount of adsorbent, initial adsorbate concentration and agitation speed was studied. The adsorption capacity of the DWCNT/iron oxide adsorbent for Cd2+ ions was 20.8 mg g-1, which is at the state of the art. The obtained results revealed that DWCNT/iron oxide composite is a very promising adsorbent for removal of Cd2+ ions from water under natural conditions. The advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process.

  1. Production of Cu/diamond composites for first-wall heat sinks

    International Nuclear Information System (INIS)

    Nunes, D.; Correia, J.B.; Carvalho, P.A.; Shohoji, N.; Fernandes, H.; Silva, C.; Alves, L.C.; Hanada, K.; Osawa, E.

    2011-01-01

    Due to their suitable thermal conductivity and strength, copper-based materials have been considered appropriate heat sinks for first wall panels in nuclear fusion devices. However, increased thermal conductivity and mechanical strength are demanded and the concept of property tailoring involved in the design of metal matrix composites advocates for the potential of nanodiamond dispersions in copper. Copper-nanodiamond composite materials can be produced by mechanical alloying followed by a consolidation operation. Yet, this powder metallurgy route poses several challenges: nanodiamond presents intrinsically difficult bonding with copper; contamination by milling media must be closely monitored; and full densification and microstructural homogeneity should be obtained with consolidation. The present line of work is aimed at an optimization of the processing conditions of Cu-nanodiamond composites. The challenges mentioned above have been addressed, respectively, by incorporating chromium in the matrix to form a stable carbide interlayer binding the two components; by assessing the contamination originating from the milling operation through particle-induced X-ray emission spectroscopy; and by comparing the densification obtained by spark plasma sintering with hot-extrusion data from previous studies.

  2. The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant

    Directory of Open Access Journals (Sweden)

    Li Zhang

    2017-06-01

    Full Text Available Plant–parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida, Heterodera glycines, Heterodera avenae and Heterodera filipjevi, in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines. Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.

  3. The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant.

    Science.gov (United States)

    Zhang, Li; Lilley, Catherine J; Imren, Mustafa; Knox, J Paul; Urwin, Peter E

    2017-01-01

    Plant-parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida , Heterodera glycines , Heterodera avenae and Heterodera filipjevi , in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines . Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.

  4. Plant-based foods containing cell wall polysaccharides rich in specific active monosaccharides protect against myocardial injury in rat myocardial infarction models

    OpenAIRE

    Sun Ha Lim; Yaesil Kim; Ki Na Yun; Jin Young Kim; Jung-Hee Jang; Mee-Jung Han; Jongwon Lee

    2016-01-01

    Many cohort studies have shown that consumption of diets containing a higher composition of foods derived from plants reduces mortality from coronary heart disease (CHD). Here, we examined the active components of a plant-based diet and the underlying mechanisms that reduce the risk of CHD using three rat models and a quantitative proteomics approach. In a short-term myocardial infarction (MI) model, intake of wheat extract (WE), the representative cardioprotectant identified by screening app...

  5. Arabinan-rich pectic polysaccharides from buriti (Mauritia flexuosa): an Amazonian edible palm fruit.

    Science.gov (United States)

    Cantu-Jungles, Thaisa Moro; Almeida, Carolina Pierobom de; Iacomini, Marcello; Cipriani, Thales R; Cordeiro, Lucimara M C

    2015-05-20

    Primary cell wall polysaccharides from aqueous extract of buriti fruit pulp (Mauritia flexuosa, an exotic tropical palm) were isolated and characterized. After freeze-thaw and α-amylase treatments, extracted polysaccharides were purified by sequential ultrafiltration through membranes. Two homogeneous fractions were obtained, SBW-100R and SBW-30R (Mw of 126 kDa and 20 kDa, respectively). Monosaccharide composition, methylation and (13)C NMR analysis showed that fraction SBW-100R contained a (1 → 5)-linked arabinan, branched at O-3 and O-2 positions, linked to a type I rhamnogalacturonan. Low amounts of these polymers were also present in fraction SBW-30R according to (13)C NMR analysis and monosaccharide composition. However, a high methyl esterified homogalacturonan (HG) was present in higher proportions. These results reinforce previous findings present in literature data which indicate that pectic polysaccharides are found in high amounts in primary cell walls of palms, which are commelinid monocotyledons. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Redox Control of Aphid Resistance through Altered Cell Wall Composition and Nutritional Quality.

    Science.gov (United States)

    Rasool, Brwa; McGowan, Jack; Pastok, Daria; Marcus, Sue E; Morris, Jenny A; Verrall, Susan R; Hedley, Peter E; Hancock, Robert D; Foyer, Christine H

    2017-09-01

    The mechanisms underpinning plant perception of phloem-feeding insects, particularly aphids, remain poorly characterized. Therefore, the role of apoplastic redox state in controlling aphid infestation was explored using transgenic tobacco ( Nicotiana tabacum ) plants that have either high (PAO) or low (TAO) ascorbate oxidase (AO) activities relative to the wild type. Only a small number of leaf transcripts and metabolites were changed in response to genotype, and cell wall composition was largely unaffected. Aphid fecundity was decreased significantly in TAO plants compared with other lines. Leaf sugar levels were increased and maximum extractable AO activities were decreased in response to aphids in all genotypes. Transcripts encoding the Respiratory Burst Oxidase Homolog F, signaling components involved in ethylene and other hormone-mediated pathways, photosynthetic electron transport components, sugar, amino acid, and cell wall metabolism, were increased significantly in the TAO plants in response to aphid perception relative to other lines. The levels of galactosylated xyloglucan were decreased significantly in response to aphid feeding in all the lines, the effect being the least in the TAO plants. Similarly, all lines exhibited increases in tightly bound (1→4)-β-galactan. Taken together, these findings identify AO-dependent mechanisms that limit aphid infestation. © 2017 American Society of Plant Biologists. All Rights Reserved.

  7. Magnetic field effects for copper suspended nanofluid venture through a composite stenosed arteries with permeable wall

    Energy Technology Data Exchange (ETDEWEB)

    Akbar, Noreen Sher; Butt, Adil Wahid, E-mail: adil.maths86@gmail.com

    2015-05-01

    In the present paper magnetic field effects for copper nanoparticles for blood flow through composite stenosis in arteries with permeable wall are discussed. The copper nanoparticles for the blood flow with water as base fluid is not explored yet. The equations for the Cu–water nanofluid are developed first time in the literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been evaluated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. The effect of various flow parameters on the flow and heat transfer characteristics is utilized. - Highlights: • It is observed that the velocity profile is symmetric for all the parameters and when we increase slip parameter α then there will be more resistance between blood and arteries, hence the blood flow slows down and velocity profile decreases. • It is seen that the velocity field rises due to high electromagnetic forces and buoyancy forces as compared to viscous forces. • It is also noticed that velocity is high for all the parameters in case of pure water as compare to Cu-water because copper makes arteries more flexible that makes the blood flow speed slow. • When we rise heat absorption parameter β then definitely temperature increases rapidly. • The wall shear stress increases for different values of the slip parameter α and the Darcy number D{sub α} with rapid change in copper as compared to pure water.

  8. Preparation of Multi-walled Carbon Nano tubes/ Natural Rubber Composite by Wet Mixing Method

    International Nuclear Information System (INIS)

    Azira Abdul Aziz; Azira Abdul Aziz; Che Su Mat Saad; Mohamad Rusop Mahmood

    2011-01-01

    Natural rubber/multi-walled carbon nano tubes (Nr/MWCNTs) nanocomposite is formed by incorporating nano tubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nano tubes will be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nano composites. Mechanical test results show an increase in the tensile strength for up to 19 times in relation to pure NR. In addition to mechanical testing, the morphology of the MWNTs into NR was studied by Field Emission Scanning Electron Microscopy (FESEM) in order to understand the morphology of the resulting system. Slight shift noted from Raman analyses from each different wt. % of MWCNTs with the NR due to the stress transfer that indicates reinforcement of the nano tubes. (author)

  9. A new method synthesis polyaniline/multi-walled carbon nanotube composites for supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pan, J.; Wei, X.; Zhou, S.P. [Shandong Univ. of Technology, Zibo (China). School of Chemical Engineering

    2010-07-01

    A series of polyaniline multi-walled nanotube (PANIMWNT) composite films were prepared using an in situ polymerization technique. Scanning electron microscopy (SEM) was used to characterize the morphology and microstructure of the samples. Cyclic voltammetry (CV), impedance spectroscopy, and galvanostatic charge/discharge analyses were used to determine the electrochemical properties of the PANIMWNT films in a 3-electrode system. The electrochemical performance of PANI, PANIMWNT, and MWNT film performances was then compared. Results of the study showed that the PANI electrodes showed a much higher capacitance than the MWNT and PANIMWNT electrodes. Both the PANI and PANIMWNT nanocomposites showed good electrochemical capacitance. The improved performance of the electrodes was attributed to the presence of sodium hypochlorite (NaClO). 5 refs.

  10. Micro/Nanomechanical characterization of multi-walled carbon nanotubes reinforced epoxy composite.

    Science.gov (United States)

    Cui, Peng; Wang, Xinnan; Tangpong, X W

    2012-11-01

    In this paper, the mechanical properties of 1 wt.% multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposites were characterized using a self-designed micro/nano three point bending tester that was on an atomic force microscope (AFM) to in situ observe MWCNTs movement on the sample surface under loading. The migration of an individual MWCNT at the surface of the nanocomposite was tracked to address the nanomechanical reinforcing mechanism of the nanocomposites. Through morphology analysis of the nanocomposite via scanning electron microscopy, AFM, and digital image correlation technique, it was found that the MWCNTs agglomerate and the bundles were the main factors for limiting the bending strength of the composites. The agglomeration/bundle effect was included in the Halpin-Tsai model to account for the elastic modulus of the nanocomposites.

  11. Carbohydrate composition and in vitro digestibility of dry matter and nonstarch polysaccharides in corn, sorghum, and wheat and coproducts from these grains.

    Science.gov (United States)

    Jaworski, N W; Lærke, H N; Bach Knudsen, K E; Stein, H H

    2015-03-01

    The objectives of this work were to determine carbohydrate composition and in vitro digestibility of DM and nonstarch polysaccharides (NSP) in corn, wheat, and sorghum and coproducts from these grains. In the initial part of this work, the carbohydrate composition of 12 feed ingredients was determined. The 12 ingredients included 3 grains (corn, sorghum, and wheat), 3 coproducts from the dry grind industry (corn distillers dried grains with solubles [DDGS] and 2 sources of sorghum DDGS), 4 coproducts from the wet milling industry (corn gluten meal, corn gluten feed, corn germ meal, and corn bran), and 2 coproducts from the flour milling industry (wheat middlings and wheat bran). Results indicated that grains contained more starch and less NSP compared with grain coproducts. The concentration of soluble NSP was low in all ingredients. Cellulose, arabinoxylans, and other hemicelluloses made up approximately 22, 49, and 29% (DM basis), respectively, of the NSP in corn and corn coproducts and approximately 25, 43, and 32% (DM basis), respectively, of the NSP in sorghum and sorghum DDGS. Cellulose, arabinoxylans, and other hemicelluloses made up approximately 16, 64, and 20% (DM basis), respectively, of the NSP in wheat and wheat coproducts. The concentration of lignin in grains was between 0.8 and 1.8% (DM basis), whereas coproducts contained between 2.2 and 11.5% lignin (DM basis). The in vitro ileal digestibility of NSP was close to zero or negative for all feed ingredients, indicating that pepsin and pancreas enzymes have no effect on in vitro degradation of NSP. A strong negative correlation ( = 0.97) between in vitro ileal digestibility of DM and the concentration of NSP in feed ingredients was observed. In vitro total tract digestibility of NSP ranged from 6.5% in corn bran to 57.3% in corn gluten meal. In conclusion, grains and grain coproducts contain mostly insoluble NSP and arabinoxylans make up the majority of the total NSP fraction. The in vitro

  12. Behavior of thin-walled beams made of advanced composite materials and incorporating non-classical effects

    Science.gov (United States)

    Librescu, Liviu; Song, Ohseop

    1991-11-01

    Several results concerning the refined theory of thin-walled beams of arbitrary closed cross-section incorporating nonclassical effects are presented. These effects are related both with the exotic properties characterizing the advanced composite material structures and the nonuniform torsional model. A special case of the general equations is used to study several problems of cantilevered thin-walled beams and to assess the influence of the incorporated effects. The results presented in this paper could be useful toward a more rational design of aeronautical or aerospace constructions, as well as of helicopter or tilt rotor blades constructed of advanced composite materials.

  13. Compositional profile and variation of Distillers Dried Grains with Solubles from various origins with focus on non-starch polysaccharides

    DEFF Research Database (Denmark)

    Pedersen, Mads Brøgger; Dalsgaard, S.; Knudsen, Knud Erik Bach

    2014-01-01

    nutrients (e.g. protein, fat, fibre and minerals) after fermentation of starch to ethanol. Corn DDGS differentiated from wheat DDGS by a greater content of fat (P≤0.006), insoluble-NSP (Pcellulose (P=0.032), and arabinose/xylose (P....001). Wheat DDGS differentiated from corn DDGS by a greater content of ash (P=0.001), soluble-NSP (Plignin (P...Corn-, wheat- and mixed cereal Distillers' Dried Grains with Solubles (DDGS) were investigated for compositional variability among DDGS origins, ethanol plants, and the relationship between corn and corresponding DDGS. A total of 138 DDGS samples were analyzed by use of Near Infrared Reflectance...

  14. Biocompatibility of single-walled carbon nanotube composites for bone regeneration.

    Science.gov (United States)

    Gupta, A; Liberati, T A; Verhulst, S J; Main, B J; Roberts, M H; Potty, A G R; Pylawka, T K; El-Amin Iii, S F

    2015-05-01

    The purpose of this study was to evaluate in vivo biocompatibility of novel single-walled carbon nanotubes (SWCNT)/poly(lactic-co-glycolic acid) (PLAGA) composites for applications in bone and tissue regeneration. A total of 60 Sprague-Dawley rats (125 g to 149 g) were implanted subcutaneously with SWCNT/PLAGA composites (10 mg SWCNT and 1gm PLAGA 12 mm diameter two-dimensional disks), and at two, four, eight and 12 weeks post-implantation were compared with control (Sham) and PLAGA (five rats per group/point in time). Rats were observed for signs of morbidity, overt toxicity, weight gain and food consumption, while haematology, urinalysis and histopathology were completed when the animals were killed. No mortality and clinical signs were observed. All groups showed consistent weight gain, and the rate of gain for each group was similar. All groups exhibited a similar pattern for food consumption. No difference in urinalysis, haematology, and absolute and relative organ weight was observed. A mild to moderate increase in the summary toxicity (sumtox) score was observed for PLAGA and SWCNT/PLAGA implanted animals, whereas the control animals did not show any response. Both PLAGA and SWCNT/PLAGA showed a significantly higher sumtox score compared with the control group at all time intervals. However, there was no significant difference between PLAGA and SWCNT/PLAGA groups. Our results demonstrate that SWCNT/PLAGA composites exhibited in vivo biocompatibility similar to the Food and Drug Administration approved biocompatible polymer, PLAGA, over a period of 12 weeks. These results showed potential of SWCNT/PLAGA composites for bone regeneration as the low percentage of SWCNT did not elicit a localised or general overt toxicity. Following the 12-week exposure, the material was considered to have an acceptable biocompatibility to warrant further long-term and more invasive in vivo studies. Cite this article: Bone Joint Res 2015;4:70-7. ©2015 The British Editorial

  15. An effective simplified model of composite compression struts for partially-restrained steel frame with reinforced concrete infill walls

    Science.gov (United States)

    Sun, Guohua; Chuang-Sheng, Walter Yang; Gu, Qiang; DesRoches, Reginald

    2018-04-01

    To resolve the issue regarding inaccurate prediction of the hysteretic behavior by micro-based numerical analysis for partially-restrained (PR) steel frames with solid reinforced concrete (RC) infill walls, an innovative simplified model of composite compression struts is proposed on the basis of experimental observation on the cracking distribution, load transferring mechanism, and failure modes of RC infill walls filled in PR steel frame. The proposed composite compression struts model for the solid RC infill walls is composed of α inclined struts and main diagonal struts. The α inclined struts are used to reflect the part of the lateral force resisted by shear connectors along the frame-wall interface, while the main diagonal struts are introduced to take into account the rest of the lateral force transferred along the diagonal direction due to the complicated interaction between the steel frame and RC infill walls. This study derives appropriate formulas for the effective widths of the α inclined strut and main diagonal strut, respectively. An example of PR steel frame with RC infill walls simulating simulated by the composite inclined compression struts model is illustrated. The maximum lateral strength and the hysteresis curve shape obtained from the proposed composite strut model are in good agreement with those from the test results, and the backbone curve of a PR steel frame with RC infill walls can be predicted precisely when the inter-story drift is within 1%. This simplified model can also predict the structural stiffness and the equivalent viscous damping ratio well when the inter-story drift ratio exceeds 0.5%.

  16. Interplay of domain walls and magnetization rotation on dynamic magnetization process in iron/polymer–matrix soft magnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Dobák, Samuel, E-mail: samuel.dobak@student.upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 041 54 Košice (Slovakia); Füzer, Ján; Kollár, Peter [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 041 54 Košice (Slovakia); Fáberová, Mária; Bureš, Radovan [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice (Slovakia)

    2017-03-15

    This study sheds light on the dynamic magnetization process in iron/resin soft magnetic composites from the viewpoint of quantitative decomposition of their complex permeability spectra into the viscous domain wall motion and magnetization rotation. We present a comprehensive view on this phenomenon over the broad family of samples with different average particles dimension and dielectric matrix content. The results reveal the pure relaxation nature of magnetization processes without observation of spin resonance. The smaller particles and higher amount of insulating resin result in the prevalence of rotations over domain wall movement. The findings are elucidated in terms of demagnetizing effects rising from the heterogeneity of composite materials. - Highlights: • A first decomposition of complex permeability into domain wall and rotation parts in soft magnetic composites. • A pure relaxation nature of dynamic magnetization processes. • A complete loss separation in soft magnetic composites. • The domain walls activity is considerably suppressed in composites with smaller iron particles and higher matrix content. • The demagnetizing field acts as a significant factor at the dynamic magnetization process.

  17. Determination of the distribution and reaction of polysaccharides in wood cell walls by the isotope tracer technique, 6: Selective radio-labeling of mannan in ginkgo (Ginkgo biloba)

    International Nuclear Information System (INIS)

    Imai, T.; Terashima, N.; Yasuda, S.

    1997-01-01

    D-Mannose-[2-H-3] and GDP (guanosine diphosphate)-D-mannose-[mannose-1-H-3] were administered to the shoots of ginkgo (Ginkgo biloba L.) tolabel mannan selectively in the cell walls. To suppress the incorporation of radioactivity into the lignin and cellulose, the precursors were administered in the presence of the inhibitor of phenylalanine ammonia-lyase (PAL): namely, L-alpha-aminooxy-beta-phenylpropionic acid (AOPP) and the inhibitor of glucan synthesis: namely, 2-deoxy-D-glucose (2-DG) and 2.6-dichlorobenzonitrile (2.6-DCB). When D-mannose-[2-H-3] was administered in the absence of the inhibitors, great radioactivities were found in the mannose and glucose obtained by sulfuric acid hydrolysis of the newly-formed xylem, and also in the vanillin obtained by nitrobenzene oxidation. These results indicate that the radioactivity was incorporated not only into mannan but also into cellulose and lignin. When D-mannose-[2-H-3] was administered in the presence of both AOPP and 2-DG, the radioactivities of vanillin and glucose were decreased but that of mannose was not decreased. These results indicate that the incorporations of radioactivities into lignin and cellulose were suppressed by the inhibitors, but the incorporation into mannan was not interfered with. The treatment with 2,6-DCB lessened the incorporations of radioactivity into vanillin, xylose, mannose, and glucose of the newly formed xylem considerably which indicated that 2,6-DCB disturbed the metabolic activities of the plant fatally. Consequently, the selective radiolabeling of mannan in ginkgo was achieved by the administration of D-mannose-[2-H-3], in the presence of both AOPP and 2-DG, toa growing stem. In the case of GDP-D-mannose-[mannose-1-H-3], the radioactivity incorporated into the newly-formed xylem was very little, and the selectivity in labeling and the effects of the inhibitors were not clear

  18. Evidence for land plant cell wall biosynthetic mechanisms in charophyte green algae

    DEFF Research Database (Denmark)

    Mikkelsen, Maria Dalgaard; Harholt, Jesper; Ulvskov, Peter

    2014-01-01

    in CGA is currently unknown, as no genomes are available, so this study sought to give insight into the evolution of the biosynthetic machinery of CGA through an analysis of available transcriptomes. METHODS: Available CGA transcriptomes were mined for cell wall biosynthesis GTs and compared with GTs...... to colonize land. These cell walls provide support and protection, are a source of signalling molecules, and provide developmental cues for cell differentiation and elongation. The cell wall of land plants is a highly complex fibre composite, characterized by cellulose cross-linked by non......-cellulosic polysaccharides, such as xyloglucan, embedded in a matrix of pectic polysaccharides. How the land plant cell wall evolved is currently unknown: early-divergent chlorophyte and prasinophyte algae genomes contain a low number of glycosyl transferases (GTs), while land plants contain hundreds. The number of GTs...

  19. Chemical composition and molecular structure of polysaccharide-protein biopolymer from Durio zibethinus seed: extraction and purification process

    Directory of Open Access Journals (Sweden)

    Amid Bahareh

    2012-10-01

    Full Text Available Abstract Background The biological functions of natural biopolymers from plant sources depend on their chemical composition and molecular structure. In addition, the extraction and further processing conditions significantly influence the chemical and molecular structure of the plant biopolymer. The main objective of the present study was to characterize the chemical and molecular structure of a natural biopolymer from Durio zibethinus seed. A size-exclusion chromatography coupled to multi angle laser light-scattering (SEC-MALS was applied to analyze the molecular weight (Mw, number average molecular weight (Mn, and polydispersity index (Mw/Mn. Results The most abundant monosaccharide in the carbohydrate composition of durian seed gum were galactose (48.6-59.9%, glucose (37.1-45.1%, arabinose (0.58-3.41%, and xylose (0.3-3.21%. The predominant fatty acid of the lipid fraction from the durian seed gum were palmitic acid (C16:0, palmitoleic acid (C16:1, stearic acid (C18:0, oleic acid (C18:1, linoleic acid (C18:2, and linolenic acid (C18:2. The most abundant amino acids of durian seed gum were: leucine (30.9-37.3%, lysine (6.04-8.36%, aspartic acid (6.10-7.19%, glycine (6.07-7.42%, alanine (5.24-6.14%, glutamic acid (5.57-7.09%, valine (4.5-5.50%, proline (3.87-4.81%, serine (4.39-5.18%, threonine (3.44-6.50%, isoleucine (3.30-4.07%, and phenylalanine (3.11-9.04%. Conclusion The presence of essential amino acids in the chemical structure of durian seed gum reinforces its nutritional value.

  20. Compositional change of some first wall materials by considering multiple step nuclear reaction

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Tetsuji; Utsumi, Misako; Fujita, Mitsutane [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)

    1997-03-01

    The conceptual system for nuclear material design is considered and some trials on WWW server with functions of the easily accessible simulation of nuclear reactions are introduced. Moreover, as an example of the simulation on the system using nuclear data, transmutation calculation was made for candidate first wall materials such as 9Cr-2W steel, V-5Cr-5Ti and SiC in SUS316/Li{sub 2}O/H{sub 2}O(SUS), 9Cr-2WLi{sub 2}O/H{sub 2}O(RAF), V alloy/Li/Be(V), and SiC/Li{sub 2}ZrO{sub 3}/He(SiC) blanket/shield systems based on ITER design model. Neutron spectrum varies with different blanket/shield compositions. The flux of low energy neutrons decreases in order of V-SiC-RAF-SUS blanket/shield systems. Fair amounts of W depletion in 9Cr-2W steel and the increase of Cr content in V-5Cr-5Ti were predicted in SUS or RAF systems. Concentration change in W and Cr is estimated to be suppressed if Li coolant is used in place of water. Helium and hydrogen production are not strongly affected by the different blanket/shield compositions. (author)

  1. Pullulan-based composite scaffolds for bone tissue engineering: Improved osteoconductivity by pore wall mineralization.

    Science.gov (United States)

    Amrita; Arora, Aditya; Sharma, Poonam; Katti, Dhirendra S

    2015-06-05

    Porous hydrogels have been explored for bone tissue engineering; however their poor mechanical properties make them less suitable as bone graft substitutes. Since incorporation of fillers is a well-accepted method for improving mechanical properties of hydrogels, in this work pullulan hydrogels were reinforced with nano-crystalline hydroxyapatite (nHAp) (5 wt% nHAp in hydrogel) and poly(3-hydroxybutyrate) (PHB) fibers (3 wt% fibers in hydrogel) containing nHAp (3 wt% nHAp in fibers). Addition of these fillers to pullulan hydrogel improved compressive modulus of the scaffold by 10 fold. However, the hydrophilicity of pullulan did not support adhesion and spreading of cells. To overcome this limitation, porous composite scaffolds were modified using a double diffusion method that enabled deposition of hydroxyapatite on pore walls. This method resulted in rapid and uniform coating of HAp throughout the three-dimensional scaffolds which not only rendered them osteoconductive in vitro but also led to an improvement in their compressive modulus. These results demonstrate the potential of mineralized pullulan-based composite scaffolds in non-load bearing bone tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Rapid Determination of the Monosaccharide Composition and Contents in Tea Polysaccharides from Yingshuang Green Tea by Pre-Column Derivatization HPLC

    Directory of Open Access Journals (Sweden)

    Yujie Ai

    2016-01-01

    Full Text Available A pre-column derivatization high-performance liquid chromatography (HPLC method was developed and optimized to characterize and quantify the monosaccharides present in tea polysaccharides (TPS isolated from Yingshuang green tea. TPS sample was hydrolyzed with trifluoroacetic acid, subjected to pre-column derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP, and separated on an Agilent TC-C18 column (4.6 mm × 250 mm, 5 μm with UV detection at 250 nm. A mixture of ten PMP derivatives of standard monosaccharides (mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, xylose, galactose, arabinose, and fucose could be baseline separated within 20 min. Moreover, quantitative analysis of the component monosaccharides in Yingshuang green tea TPS was achieved, indicating the TPS consisted of mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, xylose, galactose, and arabinose in the molar contents of 0.72, 0.78, 0.89, 0.13, 0.15, 0.36, 0.39, 0.36, 0.36, and 0.38 μM, respectively. Recovery efficiency for component monosaccharides from TPS ranged from 93.6 to 102.4% with RSD values lower than 2.5%. In conclusion, pre-column derivatization HPLC provides a rapid, reproducible, accurate, and quantitative method for analysis of the monosaccharide composition and contents in TPS, which may help to further explore the relationship between TPS monosaccharides isolated from different tea varieties and their biological activity.

  3. Sugar Composition Analysis of Fuzi Polysaccharides by HPLC-MSn and Their Protective Effects on Schwann Cells Exposed to High Glucose

    Directory of Open Access Journals (Sweden)

    Bei-Bei Wang

    2016-11-01

    Full Text Available Fuzi has been used to treat diabetic complications for many years in china. In a previous study, we have shown that Fuzi aqueous extract can attenuate Diabetic peripheral neuropathy (DPN in rats and protect Schwann cells from injury. Thus, the protective effect of Fuzi polysaccharides (FPS on high glucose-induced SCs and the preliminary mechanism were investigated. Firstly, the FPS were obtained and their monose composition was analyzed by the combination of pre-column derivatization and high performance liquid chromatography coupled with electrospray ionization multi-tandem mass spectrometry (HPLC/ESI-MSn. The results witnessed the efficiency of this method and seven monosaccharides were tentatively identified, among which fucose was first reported. Simultaneously, m/z 215 can be considered as diagnostic ions to confirm the number of monosaccharides. Next, high glucose-induced SC model was applied and divided into model group, treated group of FPS, normal and osmotic control group. After treatment for 48 h, the data showed FPS could significantly decrease the intracellular ROS and apoptosis, which were determined by the corresponding fluorescent probes. Then, the expression of oxidative stress-related proteins in SCs were measured by Western blot. Furthermore, the protein tests found that FPS markedly up-regulated superoxide dismutase (SOD, catalase (CAT and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α protein level, but down-regulated NADPH oxidase-1 (Nox1 protein level. Moreover, FPS could also increase AMP-activated protein kinase (AMPK activation significantly. Hence, we preliminary deduced that AMPK-PGC-1α pathway may play an important role in the protective effect of FPS against high glucose-induced cell damage.

  4. Molecular characterization of two Arabidopsis thaliana glycosyltransferase mutants, rra1 and rra2, which have a reduced residual arabinose content in a polymer tightly associated with the cellulosic wall residue

    DEFF Research Database (Denmark)

    Egelund, Jack; Obel, Nicolai; Ulvskov, Peter

    2007-01-01

    identified and characterized at the molecular and biochemical level. Monosaccharide compositional analyses of cell wall material isolated from the meristematic region showed a ca. 20% reduction in the arabinose content in the insoluble/undigested cell wall residue after enzymatic removal of xyloglucan...... and pectic polysaccharides. These data indicate that both RRA-1 and -2 play a role in the arabinosylation of cell wall component(s)....

  5. Effect of selected Saccharomyces cerevisiae yeast strains and different aging techniques on the polysaccharide and polyphenolic composition and sensorial characteristics of Cabernet Sauvignon red wines.

    Science.gov (United States)

    del Barrio-Galán, Rubén; Cáceres-Mella, Alejandro; Medel-Marabolí, Marcela; Peña-Neira, Álvaro

    2015-08-15

    The objective of this work was to study the effect of two Saccharomyces cerevisiae yeast strains with different capabilities of polysaccharide liberation during alcoholic fermentation in addition to subsequent aging on lees with or without oak wood chips as well as aging with commercial inactive dry yeast on the physical, chemical and sensorial characteristics of Cabernet Sauvignon red wines. The HPS (high levels of polysaccharides) yeast strain released higher amounts of polysaccharides (429 g L(-1)) than EC1118 (390 g L(-1)) during alcoholic fermentation, but the concentration equalized during the aging period (424 and 417 g L(-1) respectively). All aging techniques increased the polysaccharide concentration, but the increase was dependent on the technique applied. A higher liberation of polysaccharides reduced the concentration of most of the phenolic families analyzed. Moreover, no clear effect of the different aging techniques used in this study on color stabilization was found. The HPS wines were better valued than the EC1118 wines by the panel of tasters after alcoholic fermentation. In general, the HPS wines showed better physicochemical and sensorial characteristics than the EC1118 wines. According to the results obtained during the aging period, all aging techniques contributed to improve wine quality, but it was difficult to establish the technique that allowed the best wine to be obtained, because it depended on the aging technique used and the period of aging. © 2014 Society of Chemical Industry.

  6. Polysaccharide-producing microalgae

    Energy Technology Data Exchange (ETDEWEB)

    Braud, J.P.; Chaumont, D.; Gudin, C.; Thepenier, C.; Chassin, P.; Lemaire, C.

    1982-11-01

    The production of extracellular polysaccharides is studied with Nostoc sp (cyanophycus), Porphiridium cruentum, Rhodosorus marinus, Rhodella maculata (rhodophyci) and Chlamydomonas mexicana (chlorophycus). The polysaccharides produced are separated by centrifugation of the culture then precipitation with alcohol. Their chemical structure was studied by infrared spectrometry and acid hydrolysis. By their rheological properties and especially their insensitivity to temperatrure and pH variations the polysaccharides produced by Porphryridium cruentum and Rhodella maculata appear as suitable candidates for industrial applications.

  7. Analysis of Material Removal and Surface Characteristics in Machining Multi Walled Carbon Nanotubes Filled Alumina Composites by WEDM Process

    Directory of Open Access Journals (Sweden)

    Annebushan Singh Meinam

    2017-01-01

    Full Text Available The reinforcement of ceramic materials with electrically conductive particles increases the overall conductivity of the ceramic material. This allows the ceramic material to be more readily machined using wire electrical discharge machining process. The current work is an approach to identify the machinability of multi walled carbon nanotubes filled alumina composites in wire electrical discharge machining process. Alumina samples of 5 vol. % and 10 vol. % multi walled carbon nanotubes are machined and analysed for material removal rate and the surface characteristics. An increase in material removal rate is observed with increase in filler concentrations. At the same time, better surface roughness is observed. The surface characteristics of composite alumina are further compared with Monel 400 alloy. It has been observed that spalling action is the dominating material removal mechanism for alumina composites, while melting and evaporation is for the Monel 400 alloy.

  8. Structural characterization of pectic hairy regions isolated from apple cell walls = Structuurkenmerken van vertakte pectine fragmenten afkomstig van de celwanden van appel

    NARCIS (Netherlands)

    Schols, H.

    1995-01-01

    Cell wall pectic substances have a great influence on the production and quality aspects of apple juice. Apple juices were characterized by their polysaccharide content and composition. A pectic fraction, retained by ultrafiltration of a liquefaction juice, was isolated and termed MHR

  9. Characterization of the Sclerotinia sclerotiorum cell wall proteome.

    Science.gov (United States)

    Liu, Longzhou; Free, Stephen J

    2016-08-01

    We used a proteomic analysis to identify cell wall proteins released from Sclerotinia sclerotiorum hyphal and sclerotial cell walls via a trifluoromethanesulfonic acid (TFMS) digestion. Cell walls from hyphae grown in Vogel's glucose medium (a synthetic medium lacking plant materials), from hyphae grown in potato dextrose broth and from sclerotia produced on potato dextrose agar were used in the analysis. Under the conditions used, TFMS digests the glycosidic linkages in the cell walls to release intact cell wall proteins. The analysis identified 24 glycosylphosphatidylinositol (GPI)-anchored cell wall proteins and 30 non-GPI-anchored cell wall proteins. We found that the cell walls contained an array of cell wall biosynthetic enzymes similar to those found in the cell walls of other fungi. When comparing the proteins in hyphal cell walls grown in potato dextrose broth with those in hyphal cell walls grown in the absence of plant material, it was found that a core group of cell wall biosynthetic proteins and some proteins associated with pathogenicity (secreted cellulases, pectin lyases, glucosidases and proteases) were expressed in both types of hyphae. The hyphae grown in potato dextrose broth contained a number of additional proteins (laccases, oxalate decarboxylase, peroxidase, polysaccharide deacetylase and several proteins unique to Sclerotinia and Botrytis) that might facilitate growth on a plant host. A comparison of the proteins in the sclerotial cell wall with the proteins in the hyphal cell wall demonstrated that sclerotia formation is not marked by a major shift in the composition of cell wall protein. We found that the S. sclerotiorum cell walls contained 11 cell wall proteins that were encoded only in Sclerotinia and Botrytis genomes. © 2015 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.

  10. Structural interpretations of deformation and fracture behavior of polypropylene/multi-walled carbon nanotube composites

    International Nuclear Information System (INIS)

    Ganss, Martin; Satapathy, Bhabani K.; Thunga, Mahendra; Weidisch, Roland; Poetschke, Petra; Jehnichen, Dieter

    2008-01-01

    The deformation and crack resistance behavior of polypropylene (PP) multi-walled carbon nanotube (MWNT) composites have been studied and their interrelation to the structural attributes studied by transmission electron microscopy (TEM), atomic force microscopy (AFM), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarization light microscopy has been discussed. The composites were produced from industrial available MWNT by extrusion melt-mixing and injection-molding. In stress-strain measurements a strong increase in the yield stress and the Young's modulus at low MWNT contents has been observed, which was attributed to an efficient load transfer between the carbon nanotubes and polypropylene matrix through a good polymer-nanotube adhesion as indicated by SEM. The extent of enhancement in mechanical properties above 1.5 wt.% of MWNT decreased due to an apparently increased tendency of clustering of carbon nanotubes. Several theoretical models have been taken into account to explain the mechanical properties and to demonstrate the applicability of such models to the system under investigation. The crack resistance behavior has been studied with the essential work of fracture (EWF) approach based on post-yield fracture mechanics (PYFM) concept. A maximum in the non-essential work of fracture was observed at 0.5 wt.% MWNT demonstrating enhanced toughness compared to pure PP, followed by a sharp decline as the MWNT content was increased to 1.5 wt.% reveals a ductile-to-semi-ductile transition. Studies on the kinetics of crack propagation aspects have revealed a qualitative picture of the nature of such a transition in the fracture modes

  11. Modification of Pectin and Hemicellulose Polysaccharides in Relation to Aril Breakdown of Harvested Longan Fruit

    Science.gov (United States)

    Wang, Duoduo; Zhang, Haiyan; Wu, Fuwang; Li, Taotao; Liang, Yuxiang; Duan, Xuewu

    2013-01-01

    To investigate the modification of cell wall polysaccharides in relation to aril breakdown in harvested longan fruit, three pectin fractions (WSP, water soluble pectin; CSP, CDTA-soluble pectin; ASP, alkali soluble pectin) and one hemicellulose fraction (4 M KOH-SHC, 4 M KOH-soluble hemicellulose) were extracted, and their contents, monosaccharide compositions and molecular weights were evaluated. As aril breakdown intensified, CSP content increased while ASP and 4 M KOH-SHC contents decreased, suggesting the solubilization and conversion of cell wall components. Furthermore, the molar percentage of arabinose (Ara), as the main component of the side-chains, decreased largely in CSP and ASP while that of rhamnose (Rha), as branch point for the attachment of neutral sugar side chains, increased during aril breakdown. Analysis of (Ara + Gal)/Rha ratio showed that the depolymerization of CSP and ASP happened predominantly in side-chains formed of Ara residues. For 4 M KOH-SHC, more backbones were depolymerized during aril breakdown. Moreover, it was found that the molecular weights of CSP, ASP and 4 M KOH-SHC polysaccharides tended to decrease as aril breakdown intensified. These results suggest that both enhanced depolymerization and structural modifications of polysaccharides in the CSP, ASP and 4 M KOH-SHC fractions might be responsible for aril breakdown of harvested longan fruit. PMID:24287911

  12. Coherent polyaniline/graphene oxides/multi-walled carbon nanotubes ternary composites for asymmetric supercapacitors

    International Nuclear Information System (INIS)

    Hao, Ming; Chen, Yi; Xiong, Weilai; Zhang, Liu; Wu, Liyang; Fu, Yang; Mei, Tao; Wang, Jianying; Li, Jinhua; Wang, Xianbao

    2016-01-01

    A coherent polyaniline (PANI)/graphene oxides (GOs)/multi-walled carbon nanotubes (MWCNTs) composite was prepared by in-situ solution polymerization as a positive electrode of supercapacitors. The orderly growth of PANI nano-dots on GOs led to the formation of the nano-ravines that can enhance ions diffusion efficiency. MWCNTs surrounded by PANI connected all components, and thus the conductivity with the increasing electron transfer rate was improved. The results showed that the electrode exhibited the outstanding electrochemical performances with the specific capacitance up to 696 F g −1 at 20 mV s −1 . The KOH-activated GOs/MWCNTs were used as a negative electrode to assemble an asymmetric supercapacitor (ASC). The ASC possessed an extended working potential (1.6 V), a good rate capability (58% capacitance retention even after the current density being increased by 10 times), an excellent cycling stability (89% capacitance retention after 3000 cycles), and a decent average energy and power density (69 W h/kg and 6.4 kW/kg).

  13. Potentiometric urea biosensor based on multi-walled carbon nanotubes (MWCNTs)/silica composite material

    International Nuclear Information System (INIS)

    Ahuja, Tarushee; Kumar, D.; Singh, Nahar; Biradar, A.M.; Rajesh

    2011-01-01

    A novel potentiometric urea biosensor has been fabricated with urease (Urs) immobilized multi-walled carbon nanotubes (MWCNTs) embedded in silica matrix deposited on the surface of indium tin oxide (ITO) coated glass plate. The enzyme Urs was covalently linked with the exposed free -COOH groups of functionalized MWCNTs (F-MWCNTs), which are subsequently incorporated within the silica matrix by sol-gel method. The Urs/MWCNTs/SiO 2 /ITO composite modified electrode was characterized by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and UV-visible spectroscopy. The morphologies and electrochemical performance of the modified Urs/MWCNTs/SiO 2 /ITO electrode have been investigated by scanning electron microscopy (SEM) and potentiometric method, respectively. The synergistic effect of silica matrix, F-MWCNTs and biocompatibility of Urs/MWCNTs/SiO 2 made the biosensor to have the excellent electro catalytic activity and high stability. The resulting biosensor exhibits a good response performance to urea detection with a wide linear range from 2.18 x 10 -5 to 1.07 x 10 -3 M urea. The biosensor shows a short response time of 10-25 s and a high sensitivity of 23 mV/decade/cm 2 .

  14. Methods of saccharification of polysaccharides in plants

    Science.gov (United States)

    Howard, John; Fake, Gina

    2014-04-29

    Saccharification of polysaccharides of plants is provided, where release of fermentable sugars from cellulose is obtained by adding plant tissue composition. Production of glucose is obtained without the need to add additional .beta.-glucosidase. Adding plant tissue composition to a process using a cellulose degrading composition to degrade cellulose results in an increase in the production of fermentable sugars compared to a process in which plant tissue composition is not added. Using plant tissue composition in a process using a cellulose degrading enzyme composition to degrade cellulose results in decrease in the amount of cellulose degrading enzyme composition or exogenously applied cellulase required to produce fermentable sugars.

  15. Characterization and antioxidant activities of polysaccharides from thirteen boletus mushrooms.

    Science.gov (United States)

    Zhang, Lan; Hu, Yu; Duan, Xiaoyu; Tang, Tingting; Shen, Yingbin; Hu, Bin; Liu, Aiping; Chen, Hong; Li, Cheng; Liu, Yuntao

    2018-07-01

    Water-soluble polysaccharides were extracted from the caps and stipes of thirteen boletus mushrooms representing five different species collected in Southwest China. Investigations of their structures and antioxidant activities allowed an evaluation of structure-function relationships. The polysaccharides were composed mainly of the monosaccharides arabinose, xylose, mannose, glucose and galactose. Most samples displayed a broad molecular weight range, with significant differences observed between the molecular weight ranges of the polysaccharides from the caps and the stipes. FT-IR spectral analysis of the polysaccharides revealed that most of polysaccharides from boletus mushrooms (except Boletus edulis) contained a pyranose ring. The antioxidant activities of the polysaccharides in stipes showed a significant correlation with their monosaccharide composition, and were also related to their molecular weight and anomeric configuration. Suillellus luridus collected in Pingwu, Mianyang, Sichuan, China had remarkably superior antioxidant activity and might be developed as a natural antioxidant. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Mechanical properties of nickel-coated single-walled carbon nanotubes and their embedded gold matrix composites

    International Nuclear Information System (INIS)

    Song Haiyang; Zha Xinwei

    2010-01-01

    The effects of nickel coating on the mechanical behaviors of armchair single-walled carbon nanotubes (SWCNTs) and their embedded gold matrix composites under axial tension are investigated using molecular dynamics (MD) simulation method. The results show that the Young's moduli and tensile strength of SWCNTs obviously decrease after nickel coating. For armchair SWCNTs, the decreased ratio of the Young's moduli of SWCNTs with smaller radius is larger than that of SWCNTs with larger radius. A comparison is made between the response to Young's modulus of a composite with parallel embedded nanotube and the response of a composite with vertically embedded nanotube. The results show that the uncoated SWCNT can enhance the Young's modulus of composite under the condition of parallel embedment, but such improvement disappears under the condition of vertical embedment because the interaction between SWCNT and gold matrix is too weak for effective load transfer. However, the nickel-coated SWCNT can indeed significantly improve the composite behavior.

  17. Performance, digesta characteristics, nutrient flux, plasma composition and organ weight in pigs as effected by dietary cation anion difference and non starch polysaccharide

    NARCIS (Netherlands)

    Dersjant-Li, Y.; Verstegen, M.W.A.; Schulze, H.; Zandstra, T.; Boer, H.; Schrama, J.W.; Verreth, J.A.J.

    2001-01-01

    Two dietary cation anion difference (CAD) levels (-100 and 200 mEq/kg) and two dietary nonstarch polysaccharide (NSP) levels (10 and 15€were used in a 2 x 2 factorial arrangement in two randomized blocks (trials) to evaluate performance, digesta pH and buffer capacity, apparent digestibility, plasma

  18. Highly Stable and Flexible Pressure Sensors with Modified Multi-Walled Carbon Nanotube/Polymer Composites for Human Monitoring.

    Science.gov (United States)

    He, Yin; Ming, Yue; Li, Wei; Li, Yafang; Wu, Maoqi; Song, Jinzhong; Li, Xiaojiu; Liu, Hao

    2018-04-26

    A facile method for preparing an easy processing, repeatable and flexible pressure sensor was presented via the synthesis of modified multi-walled carbon nanotubes (m-MWNTs) and polyurethane (PU) films. The surface modification of multi-walled carbon nanotubes (MWNTs) simultaneously used a silane coupling agent (KH550) and sodium dodecyl benzene sulfonate (SDBS) to improve the dispersibility and compatibility of the MWNTs in a polymer matrix. The electrical property and piezoresistive behavior of the m-MWNT/PU composites were compared with raw multi-walled carbon nanotube (raw MWNT)/PU composites. Under linear uniaxial pressure, the m-MWNT/PU composite exhibited 4.282%kPa −1 sensitivity within the pressure of 1 kPa. The nonlinear error, hysteresis error and repeatability error of the piezoresistivity of m-MWNT/PU decreased 9%, 16.72% and 54.95% relative to raw MWNT/PU respectively. Therefore, the piezoresistive response of m-MWNT/PU had better stability than that of raw MWNT/PU composites. The m-MWNT/PU sensors could be utilized in wearable devices for body movement detection, monitoring of respiration and pressure detection in garments.

  19. In vitro evaluation of three-dimensional single-walled carbon nanotube composites for bone tissue engineering.

    Science.gov (United States)

    Gupta, Ashim; Main, Benjamin J; Taylor, Brittany L; Gupta, Manu; Whitworth, Craig A; Cady, Craig; Freeman, Joseph W; El-Amin, Saadiq F

    2014-11-01

    The purpose of this study was to develop three-dimensional single-walled carbon nanotube composites (SWCNT/PLAGA) using 10-mg single-walled carbon nanotubes (SWCNT) for bone regeneration and to determine the mechanical strength of the composites, and to evaluate the interaction of MC3T3-E1 cells via cell adhesion, growth, survival, proliferation, and gene expression. PLAGA (polylactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated, characterized, and mechanical testing was performed. MC3T3-E1 cells were seeded and cell adhesion/morphology, growth/survival, proliferation, and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, nonstressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared with PLAGA. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration, for bone tissue engineering, and are promising for orthopedic applications as they possess the combined effect of increased mechanical strength, cell proliferation, and gene expression. © 2014 Wiley Periodicals, Inc.

  20. Variable-viscosity thermal hemodynamic slip flow conveying nanoparticles through a permeable-walled composite stenosed artery

    Science.gov (United States)

    Akbar, Noreen Sher; Tripathi, Dharmendra; Bég, O. Anwar

    2017-07-01

    This paper presents a mathematical model for simulating viscous, incompressible, steady-state blood flow containing copper nanoparticles and coupled heat transfer through a composite stenosed artery with permeable walls. Wall slip hydrodynamic and also thermal buoyancy effects are included. The artery is simulated as an isotropic elastic tube, following Joshi et al. (2009), and a variable viscosity formulation is employed for the flowing blood. The equations governing the transport phenomena are non-dimensionalized and the resulting boundary value problem is solved analytically in the steady state subject to physically appropriate boundary conditions. Numerical computations are conducted to quantify the effects of relevant hemodynamic, thermophysical and nanoscale parameters emerging in the model on velocity and temperature profiles, wall shear stress, impedance resistance and also streamline distributions. The model may be applicable to drug fate transport modeling with nanoparticle agents and also to the optimized design of nanoscale medical devices for diagnosing stenotic diseases in circulatory systems.

  1. Thioridazine Induces Major Changes in Global Gene Expression and Cell Wall Composition in Methicillin-Resistant Staphylococcus aureus USA300

    DEFF Research Database (Denmark)

    Thorsing, Mette; Klitgaard, Janne Kudsk; Atilano, Magda L.

    2013-01-01

    and the transcriptomic response of S. aureus to known inhibitors of cell wall synthesis suggests that TDZ disturbs PGN biosynthesis at a stage that precedes transpeptidation by penicillin-binding proteins (PBPs). In support of this notion, dramatic changes in the muropeptide profile of USA300 were observed following....... In the present study, we have examined the effect of a subinhibitory concentration of TDZ on antimicrobial resistance, the global transcriptome, and the cell wall composition of MRSA USA300. We show that TDZ is able to sensitize the bacteria to several classes of antimicrobials targeting the late stages...... a major impact on the cell wall biosynthesis pathway in S. aureus and provides new insights into how MRSA may be sensitized towards β-lactam antibiotics....

  2. Composition and distribution of cell wall phenolic compounds in flax (Linum usitatissimum L.) stem tissues

    NARCIS (Netherlands)

    Gorshkova, T.A.; Salnikov, V.V.; Pogodina, N.M.; Chemikosova, S.B.; Yablokova, E.V.; Ulanov, A.V.; Ageeva, M.V.; Dam, van J.E.G.; Lozovaya, V.V.

    2000-01-01

    Cell wall phenolic compounds were analysed in xylem and bast fibre-rich peels of flax stems by biochemical, histochemical and ultrastructural approaches. Localization of cell wall phenolics by the enzyme-gold method using laccase revealed several gold particle distribution patterns. One of the major

  3. Cell wall composition and lignin biosynthetic gene expression along a developmental gradient in an Australian sugarcane cultivar

    Directory of Open Access Journals (Sweden)

    William P. Bewg

    2017-12-01

    Full Text Available Sugarcane bagasse is an abundant source of lignocellulosic material for bioethanol production. Utilisation of bagasse for biofuel production would be environmentally and economically beneficial, but the recalcitrance of lignin continues to provide a challenge. Further understanding of lignin production in specific cultivars will provide a basis for modification of genomes for the production of phenotypes with improved processing characteristics. Here we evaluated the expression profile of lignin biosynthetic genes and the cell wall composition along a developmental gradient in KQ228 sugarcane. The expression levels of nine lignin biosynthesis genes were quantified in five stem sections of increasing maturity and in root tissue. Two distinct expression patterns were seen. The first saw highest gene expression in the youngest tissue, with expression decreasing as tissue matured. The second pattern saw little to no change in transcription levels across the developmental gradient. Cell wall compositional analysis of the stem sections showed total lignin content to be significantly higher in more mature tissue than in the youngest section assessed. There were no changes in structural carbohydrates across developmental sections. These gene expression and cell wall compositional patterns can be used, along with other work in grasses, to inform biotechnological approaches to crop improvement for lignocellulosic biofuel production.

  4. Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition.

    Science.gov (United States)

    Podgórska, Anna; Burian, Maria; Gieczewska, Katarzyna; Ostaszewska-Bugajska, Monika; Zebrowski, Jacek; Solecka, Danuta; Szal, Bożena

    2017-01-01

    Plants mainly utilize inorganic forms of nitrogen (N), such as nitrate (NO 3 - ) and ammonium (NH 4 + ). However, the composition of the N source is important, because excess of NH 4 + promotes morphological disorders. Plants cultured on NH 4 + as the sole N source exhibit serious growth inhibition, commonly referred to as "ammonium toxicity syndrome." NH 4 + -mediated suppression of growth may be attributable to both repression of cell elongation and reduction of cell division. The precondition for cell enlargement is the expansion of the cell wall, which requires the loosening of the cell wall polymers. Therefore, to understand how NH 4 + nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH 4 + as the sole N source has smaller cells with relatively thicker cell walls. Moreover, cellulose, which is the main load-bearing polysaccharide revealed a denser assembly of microfibrils. Consequently, the leaf blade tissue showed elevated tensile strength and indicated higher cell wall stiffness. These changes might be related to changes in polysaccharide and ion content of cell walls. Further, NH 4 + toxicity was associated with altered activities of cell wall modifying proteins. The lower activity and/or expression of pectin hydrolyzing enzymes and expansins might limit cell wall expansion. Additionally, the higher activity of cell wall peroxidases can lead to higher cross-linking of cell wall polymers. Overall, the NH 4 + -mediated inhibition of growth is related to a more rigid cell wall structure, which limits expansion of cells. The changes in cell wall composition were also indicated by decreased expression of Feronia , a receptor-like kinase involved in the control of cell wall extension.

  5. Research of polysaccharide complexes from asteraceae family plants

    Directory of Open Access Journals (Sweden)

    Світлана Михайлівна Марчишин

    2015-10-01

    Full Text Available Aim of research. Depth study of polysaccharides in some little-known plant species of Asteraceae family is pressing question, considering that polysaccharides are important biologically active compounds widely used in pharmaceutical and medical practice as remedies and preventive medications. The aim of research was to determinate both quantitative content and monomeric composition of polysaccharide complexes from Asteraceae family plant species – Tagetes genus, Arnica genus, and Bellis genus.Materials and methods. Determination of polysaccharides was carried out by the precipitation reaction, using 96 % ethyl alcohol P and Fehling's solution after acid hydrolysis; quantitative content of this group of compounds was determined by gravimetric analysis. On purpose to identify the monomeric composition hydrolysis under sulfuric acid conditions was conducted. Qualitative monomeric composition of polysaccharides after hydrolysis was carried out by paper chromatography method in n-Butanol – Pyridine – Distilled water P (6:4:3 system along with saccharides reference samples.Results. Polysaccharide complexes from Tagetes erecta, Tagetes patula, Tagetes tenuifolia, Arnica montana, Arnica foliosa, wild and cultivated Bellis perennis herbs were studied. Water-soluble polysaccharides and pectin fractions were isolated from studied objects; their quantitative content and monomeric composition were determined.Conclusion. The highest amount of water-soluble polysaccharides was found in cultivated Bellis perennis herb (10,13 %, the highest amount of pectin compounds – in Tagetes tenuifolia herb (13,62 %; the lowest amount of water-soluble polysaccharides and pectin compounds was found in Arnica montana herb (4,61 % and Tagetes patula herb (3,62 %, respectively. It was found that polysaccharide complexes from all studied species include glucose and arabinose

  6. Radiation processed polysaccharide products

    International Nuclear Information System (INIS)

    Nguyen, Quoc Hien

    2007-01-01

    Radiation crosslinking, degradation and grafting techniques for modification of polymeric materials including natural polysaccharides have been providing many unique products. In this communication, typical products from radiation processed polysaccharides particularly plant growth promoter from alginate, plant protector and elicitor from chitosan, super water absorbent containing starch, hydrogel sheet containing carrageenan/CM-chitosan as burn wound dressing, metal ion adsorbent from partially deacetylated chitin were described. The procedures for producing those above products were also outlined. Future development works on radiation processing of polysaccharides were briefly presented. (author)

  7. Characterizing visible and invisible cell wall mutant phenotypes

    Energy Technology Data Exchange (ETDEWEB)

    Carpita, Nicholas C.; McCann, Maureen C.

    2015-04-06

    About 10% of a plant's genome is devoted to generating the protein machinery to synthesize, remodel, and deconstruct the cell wall. High-throughput genome sequencing technologies have enabled a reasonably complete inventory of wall-related genes that can be assembled into families of common evolutionary origin. Assigning function to each gene family member has been aided immensely by identification of mutants with visible phenotypes or by chemical and spectroscopic analysis of mutants with ‘invisible’ phenotypes of modified cell wall composition and architecture that do not otherwise affect plant growth or development. This review connects the inference of gene function on the basis of deviation from the wild type in genetic functional analyses to insights provided by modern analytical techniques that have brought us ever closer to elucidating the sequence structures of the major polysaccharide components of the plant cell wall.

  8. Behaviour of a new composite mesh for the repair of full-thickness abdominal wall defects in a rabbit model.

    Directory of Open Access Journals (Sweden)

    Gemma Pascual

    Full Text Available INTRODUCTION: Composite biomaterials designed for the repair of abdominal wall defects are composed of a mesh component and a laminar barrier in contact with the visceral peritoneum. This study assesses the behaviour of a new composite mesh by comparing it with two latest-generation composites currently used in clinical practice. METHODS: Defects (7x5cm created in the anterior abdominal wall of New Zealand White rabbits were repaired using a polypropylene mesh and the composites: Physiomesh(TM; Ventralight(TM and a new composite mesh with a three-dimensional macroporous polyester structure and an oxidized collagen/chitosan barrier. Animals were sacrificed on days 14 and 90 postimplant. Specimens were processed to determine host tissue incorporation, gene/protein expression of neo-collagens (RT-PCR/immunofluorescence, macrophage response (RAM-11-immunolabelling and biomechanical resistance. On postoperative days 7/14, each animal was examined laparoscopically to quantify adhesions between the visceral peritoneum and implant. RESULTS: The new composite mesh showed the lowest incidence of seroma in the short term. At each time point, the mesh surface covered with adhesions was greater in controls than composites. By day 14, the implants were fully infiltrated by a loose connective tissue that became denser over time. At 90 days, the peritoneal mesh surface was lined with a stable mesothelium. The new composite mesh induced more rapid tissue maturation than Physiomesh(TM, giving rise to a neoformed tissue containing more type I collagen. In Ventralight(TM the macrophage reaction was intense and significantly greater than the other composites at both follow-up times. Tensile strengths were similar for each biomaterial. CONCLUSIONS: All composites showed optimal peritoneal behaviour, inducing good peritoneal regeneration and scarce postoperative adhesion formation. A greater foreign body reaction was observed for Ventralight(TM. All composites induced

  9. Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties

    Directory of Open Access Journals (Sweden)

    Shayesteh eHaghighatpanah

    2014-09-01

    Full Text Available Molecular dynamics and molecular mechanics methods have been used to investigate additive-polymer interfacial properties in single walled carbon nanotube – polyethylene and single walled carbon nanotube – polyacrylonitrile composites. Properties such as the interfacial shear stress and bonding energy are similar for the two composites. In contrast, functionalizing the single walled carbon nanotubes with carboxylic acid groups leads to an increase in these properties, with a larger increase for the polar polyacrylonitrile composite. Increasing the percentage of carbon atoms that were functionalized from 1% to 5% also leads to an increase in the interfacial properties. In addition, the interfacial properties depend on the location of the functional groups on the single walled carbon nanotube wall.

  10. Cell Wall Composition of Neurospora crassa Under Conditions of Copper Toxicity

    OpenAIRE

    Subramanyam, C.; Venkateswerlu, G.; Rao, S. L. N.

    1983-01-01

    The mycelia of Neurospora crassa grown in the presence of high concentrations of copper were blue in color, but only on a medium containing inorganic nitrate and phosphate as the nitrogen and phosphate sources, respectively. The cell wall isolate of the blue mycelia contained large amounts (12%) of copper and higher amounts of chitosan, phosphate, and amino groups, with a 42% decrease in the chitin content. Although all the glucosamine of the cell wall of control cultures could be released wi...

  11. Enhanced mechanical properties of single walled carbon nanotube-borosilicate glass composite due to cushioning effect and localized plastic flow

    Directory of Open Access Journals (Sweden)

    Sujan Ghosh

    2011-12-01

    Full Text Available A borosilicate glass composite has been fabricated incorporating Single Wall Carbon Nanotubes (SWCNT in the glass matrix by melt-quench technique. Hardness and the fracture toughness of the composite, were found to increase moderately with respect to the base glass. Interestingly one can observe accumulation of SWCNT bundles around the crack zone though no such accumulation was observed in the crack free indentation zone. The enhanced hardness of the composite was discussed by correlating the cushioning as well as toughening behavior of the agglomerated SWCNT bundles. On the other hand enhanced plastic flow was proposed to be the prime reason for the accumulation of SWCNT bundles around the crack, which increases the toughness of the composite by reducing the crack length. Moreover to ascertain the enhanced plasticity of the composite than that of the glass we calculated the recovery resistance of glass and the composite where recovery resistance of composite was found to be higher than that of the glass.

  12. Using polysaccharides against cancer

    Directory of Open Access Journals (Sweden)

    E. Azarnoosh

    2017-11-01

    Full Text Available Background and objectives: Nowadays cancer is one of the most important concerns of the society. The adverse effects of common therapeutics and resistance of some cancerous cells to treatment have brought the necessity of new approaches towards the issue. Polysaccharides are a group of carbohydrates found in natural sources. In the present article, our goal was to show the positive effects of carbohydrates (especially polysaccharides in cancer treatment, based on literature review. Methods: The literature review was carried out between 1990 and 2017 inclusive using the following search terms: cancer, carbohydrate and polysaccharide and was performed with use of Google scholar, Medline, Scopus, PubMed, Elsevier and other similar data banks, related to medicine and pharmaceutical fields. Results: Plants like Lyceum barbarum, Astragalus membrannceous, Panax ginseng, and Antrodia camphorate have been studied with promising effects in combating cancerous cells. The polysaccharides from these plants have benefits with numerous mechanisms such as apoptosis, inhibition of angiogenesis, anti-proliferation, immunomodulation, tumor suppression, and increase in macrophage activity. Other studies showed over 200 mushrooms with anticancer effects, especially basidiomycetes (e.g. Ganoderma lucidum. Sulfated polysaccharides found in sea and animals or even a few bacteria like E. coli showed to be useful in cancer. Conclusion: Scientists are realizing the importance of natural drugs and polysaccharide as good and available sources that could give a bright future for prevention, cure and palliative therapy in cancer.

  13. Chemical Methods for the Determination of Soluble and Insoluble Non-Starch Polysaccharides - Review

    OpenAIRE

    Rodica Căpriţă; Adrian Căpriţă

    2011-01-01

    Polysaccharides are macromolecules of monosaccharides linked by glycosidic bonds. Non-starch polysaccharides(NSP) are principally non-α-glucan polysaccharides of the plant cell wall. They are a heterogeneous group ofpolysaccharides with varying degrees of water solubility, size, and structure. The water insoluble fiber fractioninclude cellulose, galactomannans, xylans, xyloglucans, and lignin, while the water-soluble fibers are the pectins,arabinogalactans, arabinoxylans, and β-(1,3)(1,4)-D-g...

  14. The analysis of thin walled composite laminated helicopter rotor with hierarchical warping functions and finite element method

    Science.gov (United States)

    Zhu, Dechao; Deng, Zhongmin; Wang, Xingwei

    2001-08-01

    In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single closed cell. This method is the development and extension of the traditional constrained warping theory of thin walled metallic beams, which had been proved very successful since 1940s. The warping distribution along the perimeter of each layer is expanded into a series of successively corrective warping functions with the traditional warping function caused by free torsion or free bending as the first term, and is assumed to be piecewise linear along the thickness direction of layers. The governing equations are derived based upon the variational principle of minimum potential energy for static analysis and Rayleigh Quotient for free vibration analysis. Then the hierarchical finite element method is introduced to form a numerical algorithm. Both static and natural vibration problems of sample box beams are analyzed with the present method to show the main mechanical behavior of the thin walled composite laminated helicopter rotor.

  15. Mechanical properties of PET composites using multi-walled carbon nanotubes functionalized by inorganic and itaconic acids

    Directory of Open Access Journals (Sweden)

    A. May-Pat

    2012-02-01

    Full Text Available Multi-walled carbon nanotubes (MWCNTs were oxidized by two different acid treatments and further functionalized with itaconic acid (IA. The functionalized MWCNTs were used to fabricate Poly(ethylene terephthalate (PET composites by melt mixing. The presence of functional groups on the surface of the treated MWCNTs was confirmed by infrared spectroscopy and thermogravimetric analysis. The MWCNTs oxidized with a concentrated mixture of HNO3 and H2SO4 exhibited more oxygen containing functional groups (OH, COOH but also suffer larger structural degradation than those oxidized by a mild treatment based on diluted HNO3 followed by H2O2. PET composites were fabricated using the oxidized-only and oxidized followed by functionalization with IA MWCNTs. PET composites fabricated with MWCNT oxidized by mild conditions showed improved tensile strength and failure strain, while harsh MWCNT oxidation render them overly brittle.

  16. Decoration of multi-walled carbon nanotubes by polymer wrapping and its application in MWCNT/polyethylene composites.

    Science.gov (United States)

    Hsiao, An-En; Tsai, Shu-Ya; Hsu, Mei-Wen; Chang, Shinn-Jen

    2012-05-06

    We dispersed the non-covalent functionalization of multi-walled carbon nanotubes (CNTs) with a polymer dispersant and obtained a powder of polymer-wrapped CNTs. The UV-vis absorption spectrum was used to investigate the optimal weight ratio of the CNTs and polymer dispersant. The powder of polymer-wrapped CNTs had improved the drawbacks of CNTs of being lightweight and difficult to process, and it can re-disperse in a solvent. Then, we blended the polymer-wrapped CNTs and polyethylene (PE) by melt-mixing and produced a conductive masterbatch and CNT/PE composites. The polymer-wrapped CNTs showed lower surface resistivity in composites than the raw CNTs. The scanning electron microscopy images also showed that the polymer-wrapped CNTs can disperse well in composites than the raw CNTs.

  17. Glycoprotein of the wall of sycamore tissue-culture cells.

    Science.gov (United States)

    Heath, M F; Northcote, D H

    1971-12-01

    1. A glycoprotein containing a large amount of hydroxyproline is present in the cell walls of sycamore callus cells. This protein is insoluble and remained in the alpha-cellulose when a mild separation procedure was used to obtain the polysaccharide fractions of the wall. The glycoprotein contained a high proportion of arabinose and galactose. 2. Soluble glycopeptides were prepared from the alpha-cellulose fraction when peptide bonds were broken by hydrazinolysis. The soluble material was fractionated by gel filtration and one glycopeptide was further purified by electrophoresis; it had a composition of 10% hydroxyproline, 35% arabinose and 55% galactose, and each hydroxyproline residue carried a glycosyl radical so that the oligosaccharides on the glycopeptide had an average degree of polymerization of 9. 3. The extraction of the glycopeptides was achieved without cleavage of glycosyl bonds, so that the glycoprotein cannot act as a covalent cross-link between the major polysaccharides of the wall. 4. The wall protein approximates in conformation to polyhydroxyproline and therefore it probably has similar physicochemical properties to polyhydroxyproline. This is discussed in relation to the function of the glycoprotein and its effect on the physical and chemical nature of the wall.

  18. The cell wall: a carbohydrate armour for the fungal cell.

    Science.gov (United States)

    Latgé, Jean-Paul

    2007-10-01

    The cell wall is composed of a polysaccharide-based three-dimensional network. Considered for a long time as an inert exoskeleton, the cell wall is now seen as a dynamic structure that is continuously changing as a result of the modification of culture conditions and environmental stresses. Although the cell wall composition varies among fungal species, chemogenomic comparative analysis have led to a better understanding of the genes and mechanisms involved in the construction of the common central core composed of branched beta1,3 glucan-chitin. Because of its essential biological role, unique biochemistry and structural organization and the absence in mammalian cells of most of its constitutive components, the cell wall is an attractive target for the development of new antifungal agents. Genomic as well as drug studies have shown that the death of the fungus can result from inhibition of cell wall polysaccharide synthases. To date, only beta1,3 glucan synthase inhibitors have been launched clinically and many more targets remain to be explored.

  19. Insights into plant cell wall structure, architecture, and integrity using glycome profiling of native and AFEXTM-pre-treated biomass

    Science.gov (United States)

    Pattathil, Sivakumar; Hahn, Michael G.; Dale, Bruce E.; Chundawat, Shishir P. S.

    2015-01-01

    Cell walls, which constitute the bulk of plant biomass, vary considerably in their structure, composition, and architecture. Studies on plant cell walls can be conducted on both native and pre-treated plant biomass samples, allowing an enhanced understanding of these structural and compositional variations. Here glycome profiling was employed to determine the relative abundance of matrix polysaccharides in several phylogenetically distinct native and pre-treated plant biomasses. Eight distinct biomass types belonging to four different subgroups (i.e. monocot grasses, woody dicots, herbaceous dicots, and softwoods) were subjected to various regimes of AFEX™ (ammonia fiber expansion) pre-treatment [AFEX is a trademark of MBI, Lansing (http://www.mbi.org]. This approach allowed detailed analysis of close to 200 cell wall glycan epitopes and their relative extractability using a high-throughput platform. In general, irrespective of the phylogenetic origin, AFEX™ pre-treatment appeared to cause loosening and improved accessibility of various xylan epitope subclasses in most plant biomass materials studied. For most biomass types analysed, such loosening was also evident for other major non-cellulosic components including subclasses of pectin and xyloglucan epitopes. The studies also demonstrate that AFEX™ pre-treatment significantly reduced cell wall recalcitrance among diverse phylogenies (except softwoods) by inducing structural modifications to polysaccharides that were not detectable by conventional gross composition analyses. It was found that monitoring changes in cell wall glycan compositions and their relative extractability for untreated and pre-treated plant biomass can provide an improved understanding of variations in structure and composition of plant cell walls and delineate the role(s) of matrix polysaccharides in cell wall recalcitrance. PMID:25911738

  20. Influence of essential oil of Hyssopus officinalis on the chemical composition of the walls of Aspergillus fumigatus (Fresenius).

    Science.gov (United States)

    Ghfir, B; Fonvieille, J L; Dargent, R

    1997-07-01

    The cell walls of the growing hyphae of Aspergillus fumigatus (Fresenius) cultured in the presence or absence of the essential oil of Hyssopus officinalis were isolated and their chemical composition analysed. The presence of the essential oil led to a reduction in levels of neutral sugars, uronic acid and proteins, whereas amino sugars, lipids and phosphorus levels were increased. HPLC analysis of the neutral sugars showed that they consisted mainly of glucose, mannose and galactose, while the amino sugars consisted of glucosamine and galactosamine. The presence of the essential oil in the culture medium induced marked changes in the content of galactose and galactosamine. Cell walls were fractionated by treatment with alkali and acid. The essential oil induced similar alterations in the various fractions with a more marked effect on the major constituents. The alterations were related to changes in the structure of the cells.

  1. Comparative thermal performance of static sunshade and brick cavity wall for energy efficient building envelope in composite climate

    Directory of Open Access Journals (Sweden)

    Charde Meghana

    2014-01-01

    Full Text Available Energy efficient building technologies can reduce energy consumption in buildings. In present paper effect of designed static sunshade, brick cavity wall with brick projections and their combined effect on indoor air temperature has been analyzed by constructing three test rooms each of habitable dimensions (3.0 m × 4.0 m × 3.0 m and studying hourly temperatures on typical days for one month in summer and winter each. The three rooms have also been simulated using a software and the results have been compared with the experimental results. Designed static sunshade increased indoor air temperature in winter while proposed brick cavity wall with brick projections lowered it in summer. Combined effect of building elements lowered indoor air temperature in summer and increased it in winter as compared to outdoor air temperature. It is thus useful for energy conservation in buildings in composite climate.

  2. Thermo-mechanical design windows for SiC/SiC composite first wall of A-SSTR2

    International Nuclear Information System (INIS)

    He Kaihui; Satoshi Nishio

    2002-01-01

    The finite element analysis and calculation is performed for the blanket first wall made of SiC/SiC composite material for Advanced Steady-state Tokamak Reactor 2, A-SSTR2, which is now conceptually designed in Naka Fusion Research Establishment, JAERI. Comparison analysis and design window is analyzed by using the finite element code ADINA 7.4. Through 2D calculation for various geometrical configurations and sensitive material properties, a fundamental guideline for first wall and blanket design is established with respect to maximum temperature, thermal and mechanical stress for many configurations. To satisfy hydrodynamic requirement, a4d4 (the dimension of coolant channel is 4 mm x 8 mm, and the distance between neighboring channels is 4 mm) is chosen as design point for high thermal conductivity up to 50 W/m·K

  3. Rapid Determination of the Monosaccharide Composition and Contents in Tea Polysaccharides from Yingshuang Green Tea by Pre-Column Derivatization HPLC

    OpenAIRE

    Ai, Yujie; Yu, Zhi; Chen, Yuqiong; Zhu, Xiaojing; Ai, Zeyi; Liu, Shuyuan; Ni, Dejiang

    2016-01-01

    A pre-column derivatization high-performance liquid chromatography (HPLC) method was developed and optimized to characterize and quantify the monosaccharides present in tea polysaccharides (TPS) isolated from Yingshuang green tea. TPS sample was hydrolyzed with trifluoroacetic acid, subjected to pre-column derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP), and separated on an Agilent TC-C18 column (4.6 mm × 250 mm, 5 μm) with UV detection at 250 nm. A mixture of ten PMP derivatives of...

  4. Recent Advances in Marine Algae Polysaccharides: Isolation, Structure, and Activities.

    Science.gov (United States)

    Xu, Shu-Ying; Huang, Xuesong; Cheong, Kit-Leong

    2017-12-13

    Marine algae have attracted a great deal of interest as excellent sources of nutrients. Polysaccharides are the main components in marine algae, hence a great deal of attention has been directed at isolation and characterization of marine algae polysaccharides because of their numerous health benefits. In this review, extraction and purification approaches and chemico-physical properties of marine algae polysaccharides (MAPs) are summarized. The biological activities, which include immunomodulatory, antitumor, antiviral, antioxidant, and hypolipidemic, are also discussed. Additionally, structure-function relationships are analyzed and summarized. MAPs' biological activities are closely correlated with their monosaccharide composition, molecular weights, linkage types, and chain conformation. In order to promote further exploitation and utilization of polysaccharides from marine algae for functional food and pharmaceutical areas, high efficiency, and low-cost polysaccharide extraction and purification methods, quality control, structure-function activity relationships, and specific mechanisms of MAPs activation need to be extensively investigated.

  5. Chromatography in characterization of polysaccharides from medicinal plants and fungi.

    Science.gov (United States)

    Hu, De-jun; Cheong, Kit-leong; Zhao, Jing; Li, Shao-ping

    2013-01-01

    Polysaccharides isolated from medicinal plants and fungi exhibit multiple pharmacological activities. The biological activities of polysaccharides depend on their chemical characteristics. However, characterization of polysaccahrides is a challenge because of their complicated structure and macromolecular mass. In this review, chromatography in characterization of polysaccharides, including physicochemical characterization (purity, molecular mass, and distribution), structural characterization (constituent monosaccharide composition and the ratio, the features of glycosidic linkages), and fingerprint of polysaccharides (acidic and enzymatic hydrolysates), from medicinal plants and fungi were reviewed and discussed according to the publications collected in Web of Science since 2007. The perspective for characterization of polysaccharides has also been described. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Comparison of polysaccharides from two species of Ganoderma.

    Science.gov (United States)

    Xie, Jing; Zhao, Jing; Hu, De-Jun; Duan, Jin-Ao; Tang, Yu-Ping; Li, Shao-Ping

    2012-01-13

    Ganoderma lucidum and Ganoderma sinense, known as Lingzhi in Chinese, are commonly used Chinese medicines with excellent beneficial health effects. Triterpenes and polysaccharides are usually considered as their main active components. However, the content of triterpenes differs significantly between the two species of Ganoderma. To date, a careful comparison of polysaccharides from the two species of Ganoderma has not been performed. In this study, polysaccharides from fruiting bodies of two species of Lingzhi collected from different regions of China were analyzed and compared based on HPSEC-ELSD and HPSEC-MALLS-RI analyses, as well as enzymatic digestion and HPTLC of acid hydrolysates. The results indicated that both the HPSEC-ELSD profiles and the molecular weights of the polysaccharides were similar. Enzymatic digestion showed that polysaccharides from all samples of Lingzhi could be hydrolyzed by pectinase and dextranase. HPTLC profiles of their TFA hydrolysates colored with different reagents and their monosaccharides composition were also similar.

  7. Modified polysaccharides as alternative binders for foundry industry

    Directory of Open Access Journals (Sweden)

    K. Kaczmarska

    2016-10-01

    Full Text Available Polysaccharides constitute a wide group of important polymers with many commercial applications, for example food packaging, fibres, coatings, adhesives etc. This review is devoted to the presentation of polysaccharide application in foundry industry. In this paper the selected properties of foundry moulding sand and core sand containing modified polysaccharides as binders are presented according to foreign literature data. Also, author’s own research about effect of using moulding sand binder consisting of modified polysaccharide (modified starch or its composition with non-toxic synthetic polymers are discussed. Based on technologies taken under consideration in this paper, it could be concluded that polysaccharides are suitable as an alternative for use as binder in foundry moulding applications.

  8. Vibrational behavior of adaptive aircraft wing structures modelled as composite thin-walled beams

    Science.gov (United States)

    Song, O.; Librescu, L.; Rogers, C. A.

    1992-01-01

    The vibrational behavior of cantilevered aircraft wings modeled as thin-walled beams and incorporating piezoelectric effects is studied. Based on the converse piezoelectric effect, the system of piezoelectric actuators conveniently located on the wing yield the control of its associated vertical and lateral bending eigenfrequencies. The possibility revealed by this study enabling one to increase adaptively the eigenfrequencies of thin-walled cantilevered beams could play a significant role in the control of the dynamic response and flutter of wing and rotor blade structures.

  9. Optimisation of the electromagnetic matching of manganese dioxide/multi-wall carbon nanotube composites as dielectric microwave-absorbing materials

    International Nuclear Information System (INIS)

    Ting, Tzu-Hao; Chiang, Chih-Chia; Lin, Po-Chuan; Lin, Chia-Huei

    2013-01-01

    An optimised composite sample was prepared using two dielectric materials manganese dioxide (MnO 2 ) and multi-wall carbon nanotubes (MWNTs) in an epoxy-resin matrix. Structural characterisations of both the synthesised manganese dioxide (MnO 2 ) and the multi-wall carbon nanotubes (MWNTs) were performed by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microwave absorption properties of dielectric composites with different weight fractions of MnO 2 were investigated by measuring the complex permittivity, the complex permeability and the reflection loss in the 2–18 and 18–40 GHz microwave frequency ranges using the free space method. The complex permittivity varied with the MnO 2 content, and the results show that a high concentration of fillers increased the dielectric constant. Therefore, the appropriate combination of components and experimental conditions can produce materials with specific characteristic for use as wide-band microwave absorbers. - Highlights: ► This paper analyses optimised microwave absorption for MnO 2 /MWNT composites. ► Structural characterisations were performed by using XRD and SEM. ► Increasing MnO 2 content enhances the complex permittivity in MnO 2 /MWNT matrix. ► The reflection loss varies with changes content of MnO 2 for required frequency bands

  10. Immunomodulatory dietary polysaccharides: a systematic review of the literature

    Directory of Open Access Journals (Sweden)

    Nelson Erika D

    2010-11-01

    Full Text Available Abstract Background A large body of literature suggests that certain polysaccharides affect immune system function. Much of this literature, however, consists of in vitro studies or studies in which polysaccharides were injected. Their immunologic effects following oral administration is less clear. The purpose of this systematic review was to consolidate and evaluate the available data regarding the specific immunologic effects of dietary polysaccharides. Methods Studies were identified by conducting PubMed and Google Scholar electronic searches and through reviews of polysaccharide article bibliographies. Only articles published in English were included in this review. Two researchers reviewed data on study design, control, sample size, results, and nature of outcome measures. Subsequent searches were conducted to gather information about polysaccharide safety, structure and composition, and disposition. Results We found 62 publications reporting statistically significant effects of orally ingested glucans, pectins, heteroglycans, glucomannans, fucoidans, galactomannans, arabinogalactans and mixed polysaccharide products in rodents. Fifteen controlled human studies reported that oral glucans, arabinogalactans, heteroglycans, and fucoidans exerted significant effects. Although some studies investigated anti-inflammatory effects, most studies investigated the ability of oral polysaccharides to stimulate the immune system. These studies, as well as safety and toxicity studies, suggest that these polysaccharide products appear to be largely well-tolerated. Conclusions Taken as a whole, the oral polysaccharide literature is highly heterogenous and is not sufficient to support broad product structure/function generalizations. Numerous dietary polysaccharides, particularly glucans, appear to elicit diverse immunomodulatory effects in numerous animal tissues, including the blood, GI tract and spleen. Glucan extracts from the Trametes versicolor

  11. Cell wall composition and digestibility alterations in Brachypodium distachyon achieved through reduced expression of the UDP-arabinopyranose mutase

    Science.gov (United States)

    Rancour, David M.; Hatfield, Ronald D.; Marita, Jane M.; Rohr, Nicholas A.; Schmitz, Robert J.

    2015-01-01

    Nucleotide-activated sugars are essential substrates for plant cell-wall carbohydrate-polymer biosynthesis. The most prevalent grass cell wall (CW) sugars are glucose (Glc), xylose (Xyl), and arabinose (Ara). These sugars are biosynthetically related via the UDP–sugar interconversion pathway. We sought to target and generate UDP–sugar interconversion pathway transgenic Brachypodium distachyon lines resulting in CW carbohydrate composition changes with improved digestibility and normal plant stature. Both RNAi-mediated gene-suppression and constitutive gene-expression approaches were performed. CWs from 336 T0 transgenic plants with normal appearance were screened for complete carbohydrate composition. RNAi mutants of BdRGP1, a UDP-arabinopyranose mutase, resulted in large alterations in CW carbohydrate composition with significant decreases in CW Ara content but with minimal change in plant stature. Five independent RNAi-RGP1 T1 plant lines were used for in-depth analysis of plant CWs. Real-time PCR analysis indicated that gene expression levels for BdRGP1, BdRGP2, and BdRGP3 were reduced in RNAi-RGP1 plants to 15–20% of controls. CW Ara content was reduced by 23–51% of control levels. No alterations in CW Xyl and Glc content were observed. Corresponding decreases in CW ferulic acid (FA) and ferulic acid-dimers (FA-dimers) were observed. Additionally, CW p-coumarates (pCA) were decreased. We demonstrate the CW pCA decrease corresponds to Ara-coupled pCA. Xylanase-mediated digestibility of RNAi-RGP1 Brachypodium CWs resulted in a near twofold increase of released total carbohydrate. However, cellulolytic hydrolysis of CW material was inhibited in leaves of RNAi-RGP1 mutants. Our results indicate that targeted manipulation of UDP–sugar biosynthesis can result in biomass with substantially altered compositions and highlights the complex effect CW composition has on digestibility. PMID:26136761

  12. Development and application of new composite grouting material for sealing groundwater inflow and reinforcing wall rock in deep mine.

    Science.gov (United States)

    Jinpeng, Zhang; Limin, Liu; Futao, Zhang; Junzhi, Cao

    2018-04-04

    With cement, bentonite, water glass, J85 accelerator, retarder and water as raw materials, a new composite grouting material used to seal groundwater inflow and reinforce wall rock in deep fractured rock mass was developed in this paper. Based on the reaction mechanism of raw material, the pumpable time, stone rate, initial setting time, plastic strength and unconfined compressive strength of multi-group proportion grouts were tested by orthogonal experiment. Then, the optimum proportion of composite grouting material was selected and applied to the grouting engineering for sealing groundwater inflow and reinforcing wall rock in mine shaft lining. The results show the mixing proportion of the maximum pumpable time, maximum stone rate and minimum initial setting time of grout are A K4 B K1 C K4 D K2 , A K3 B K1 C K1 D K4 and A K3 B K3 C K4 D K1 , respectively. The mixing proportion of the maximum plastic strength and unconfined compressive strength of grouts concretion bodies are A K1 B K1 C K1 D K3 and A K1 B K1 C K1 D K1 , respectively. Balanced the above 5 indicators overall and determined the optimum proportion of grouts: bentonite-cement ratio of 1.0, water-solid ratio of 3.5, accelerator content of 2.9% and retarder content of 1.45%. This new composite grouting material had good effect on the grouting engineering for sealing groundwater inflow and reinforcing wall rock in deep fractured rock mass.

  13. Polysaccharide components from the scape of Musa paradisiaca: main structural features of water-soluble polysaccharide component.

    Science.gov (United States)

    Anjaneyalu, Y V; Jagadish, R L; Raju, T S

    1997-06-01

    Polysaccharide components present in the pseudo-stem (scape) of M. paradisiaca were purified from acetone powder of the scape by delignification followed by extraction with aqueous solvents into water soluble polysaccharide (WSP), EDTA-soluble polysaccharide (EDTA-SP), alkali-soluble polysaccharide (ASP) and alkali-insoluble polysaccharide (AISP) fractions. Sugar compositional analysis showed that WSP and EDTA-SP contained only D-Glc whereas ASP contained D-Glc, L-Ara and D-Xyl in approximately 1:1:10 ratio, respectively, and AISP contained D-Glc, L-Ara and D-Xyl in approximately 10:1:2 ratio, respectively. WSP was further purified by complexation with iso-amylalcohol and characterized by specific rotation, IR spectroscopy, Iodine affinity, ferricyanide number, blue value, hydrolysis with alpha-amylase and glucoamylase, and methylation linkage analysis, and shown to be a amylopectin type alpha-D-glucan.

  14. In-situ Raman microprobe studies of plant cell walls: macromolecular organization and compositional variability in the secondary wall of Picea mariana (Mill.) B.S.P.

    Science.gov (United States)

    U.P. Agarwal; R.H. Atalla

    1986-01-01

    Native-state organization and distribution of cell-wall components in the secondary wall of woody tissue from P. mariana (Black Spruce) have been investigated using polarized Raman microspectroscopy. Evidence for orientation is detected through Raman intensity variations resulting from rotations of the exciting electric vector with respect to cell-wall geometry....

  15. Fracture toughness of epoxy/multi-walled carbon nanotube nano-composites under bending and shear loading conditions

    International Nuclear Information System (INIS)

    Ayatollahi, M.R.; Shadlou, S.; Shokrieh, M.M.

    2011-01-01

    Research highlights: → Mode I and mode II fracture tests were conducted on epoxy/MWCNT nano-composites. → Addition of MWCNT to epoxy increased both K Ic and K IIc of nano-composites. → The improvement in K IIc was more pronounced than in K Ic . → Mode I and mode II fracture surfaces were studied by scanning electron microscopy. -- Abstract: The effects of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties of epoxy/MWCNT nano-composites were studied with emphasis on fracture toughness under bending and shear loading conditions. Several finite element (FE) analyses were performed to determine appropriate shear loading boundary conditions for a single-edge notch bend specimen (SENB) and an equation was derived for calculating the shear loading fracture toughness from the fracture load. It was seen that the increase in fracture toughness of nano-composite depends on the type of loading. That is to say, the presence of MWCNTs had a greater effect on fracture toughness of nano-composites under shear loading compared with normal loading. To study the fracture mechanisms, several scanning electron microscopy (SEM) pictures were taken from the fracture surfaces. A correlation was found between the characteristics of fracture surface and the mechanical behaviors observed in the fracture tests.

  16. Ultralow percolation threshold of single walled carbon nanotube-epoxy composites synthesized via an ionic liquid dispersant/initiator

    International Nuclear Information System (INIS)

    Watters, Arianna L; Palmese, Giuseppe R

    2014-01-01

    Uniform dispersion of single walled carbon nanotubes (SWNTs) in an epoxy was achieved by a streamlined mechano-chemical processing method. SWNT-epoxy composites were synthesized using a room temperature ionic liquid (IL) with an imidazolium cation and dicyanamide anion. The novel approach of using ionic liquid that behaves as a dispersant for SWNTs and initiator for epoxy polymerization greatly simplifies nanocomposite synthesis. The material was processed using simple and scalable three roll milling. The SWNT dispersion of the resultant composite was evaluated by electron microscopy and electrical conductivity measurements in conjunction with percolation theory. Processing conditions were optimized to achieve the lowest possible percolation threshold, 4.29 × 10 −5 volume fraction SWNTs. This percolation threshold is among the best reported in literature yet it was obtained using a streamlined method that greatly simplifies processing. (paper)

  17. Ultralow percolation threshold of single walled carbon nanotube-epoxy composites synthesized via an ionic liquid dispersant/initiator

    Science.gov (United States)

    Watters, Arianna L.; Palmese, Giuseppe R.

    2014-09-01

    Uniform dispersion of single walled carbon nanotubes (SWNTs) in an epoxy was achieved by a streamlined mechano-chemical processing method. SWNT-epoxy composites were synthesized using a room temperature ionic liquid (IL) with an imidazolium cation and dicyanamide anion. The novel approach of using ionic liquid that behaves as a dispersant for SWNTs and initiator for epoxy polymerization greatly simplifies nanocomposite synthesis. The material was processed using simple and scalable three roll milling. The SWNT dispersion of the resultant composite was evaluated by electron microscopy and electrical conductivity measurements in conjunction with percolation theory. Processing conditions were optimized to achieve the lowest possible percolation threshold, 4.29 × 10-5 volume fraction SWNTs. This percolation threshold is among the best reported in literature yet it was obtained using a streamlined method that greatly simplifies processing.

  18. A cytochemical and immunocytochemical analysis of the wall labyrinth apparatus in leaf transfer cells in Elodea canadensis.

    Science.gov (United States)

    Ligrone, Roberto; Vaughn, Kevin C; Rascio, Nicoletta

    2011-04-01

    Transfer cells are plant cells specialized in apoplast/symplast transport and characterized by a distinctive wall labyrinth apparatus. The molecular architecture and biochemistry of the labyrinth apparatus are poorly known. The leaf lamina in the aquatic angiosperm Elodea canadensis consists of only two cell layers, with the abaxial cells developing as transfer cells. The present study investigated biochemical properties of wall ingrowths and associated plasmalemma in these cells. Leaves of Elodea were examined by light and electron microscopy and ATPase activity was localized cytochemically. Immunogold electron microscopy was employed to localize carbohydrate epitopes associated with major cell wall polysaccharides and glycoproteins. The plasmalemma associated with the wall labyrinth is strongly enriched in light-dependent ATPase activity. The wall ingrowths and an underlying wall layer share an LM11 epitope probably associated with glucuronoarabinoxylan and a CCRC-M7 epitope typically associated with rhamnogalacturonan I. No labelling was observed with LM10, an antibody that recognizes low-substituted and unsubstituted xylan, a polysaccharide consistently associated with secondary cell walls. The JIM5 and JIM7 epitopes, associated with homogalacturonan with different degrees of methylation, appear to be absent in the wall labyrinth but present in the rest of cell walls. The wall labyrinth apparatus of leaf transfer cells in Elodea is a specialized structure with distinctive biochemical properties. The high level of light-dependent ATPase activity in the plasmalemma lining the wall labyrinth is consistent with a formerly suggested role of leaf transfer cells in enhancing inorganic carbon inflow. The wall labyrinth is a part of the primary cell wall. The discovery that the wall ingrowths in Elodea have an antibody-binding pattern divergent, in part, from that of the rest of cell wall suggests that their carbohydrate composition is modulated in relation to transfer

  19. Production of bacterial polysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Ellwood, D C; Evans, C G.T.; Yeo, R G

    1978-06-01

    A process for the biochemical synthesis of polysaccharides comprises growing polysaccharide-producing bacteria of the genus Xanthomonas in a single stage continuous culture in a chemically-defined medium. The term chemically-defined medium denotes a culture medium wherein nutrients other than carbon are provided as inorganic salts or single organic compounds of known molecular structure rather than as complex naturally-derived mixtures. Normally the only organic component of the chemically-defined medium will be a conventional carbon source such as a carbohydrate, especially glucose, or glycerol. Preferably the medium should contain only one nitrogen source, since the use of multiple nitrogen sources, as present in complex media, appears to promote changes in the nature of the culture resulting in loss of polysaccharide production. 22 claims.

  20. Polyaniline/single-wall carbon nanotube (PANI/SWCNT) composites for high performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Vinay; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2006-12-01

    PANI/SWCNT composites were prepared by electrochemical polymerisation of polyaniline onto SWCNTs and their capacitive performance was evaluated by means of cyclic voltammetry and charge-discharge cycling in 1M H{sub 2}SO{sub 4} electrolyte. The PANI/SWCNT composites single electrode showed much higher specific capacitance, specific energy and specific power than pure PANI and SWCNTs. The highest specific capacitance, specific power and specific energy values of 485F/g, 228Wh/kg and 2250W/kg were observed for 73wt.% PANI deposited onto SWCNTs. PANI/SWCNT composites also showed long cyclic stability. Based upon the variations in the surface morphologies and specific capacitance of the composite, a mechanism is proposed to explain enhancement in the capacitive characteristics. The PANI/SWCNT composites have demonstrated the potential as excellent electrode materials for application in high performance supercapacitors. (author)

  1. Twin-screw extrusion of multi walled carbon nanotubes reinforced polycarbonate composites: Investigation of electrical and mechanical properties

    International Nuclear Information System (INIS)

    Mack, C; Sathyanarayana, S; Weiss, P; Mikonsaari, I; Hübner, C; Henning, F; Elsner, P

    2012-01-01

    1, 3 and 5 wt.% multi walled carbon nanotubes (MWCNT) reinforced polycarbonate (PC) composites were processed in a twin-screw extruder (L/D=52) with two different screw speeds, throughputs and screw configurations. Extruded strands were characterized for dispersion and measurement of electrical resistivities while the pelletized extrudates were injection molded to produce samples for mechanical and further electrical property measurements. The absolute resistance of the melt was recorded with an online melt resistance setup developed by our group. The volume resistivity of pure PC (10 17 Ω.m) was lowered to 10 4 − 10 5 Ω.m on an injection molded PC-1 wt. % MWCNT composite. 3 wt.% MWCNT incorporated composites showed volume resistivity less than 1 Ω.m independent of process conditions. At lower filler contents the volume resistivity of injection molded samples were higher than those observed on the extruded strands and this effect diminished with increasing MWCNT loadings; owing to the loss of CNT network contacts due to shear induced filler orientation and core-skin effects. The quality of dispersion was exceptional for all filler concentrations at any process condition owing to the affinity of MWCNT towards PC due to the lower interfacial energy difference between the reactants and high polarity of PC. The modulus and strength of the composites increased with filler addition, however at 5 wt.% filler loading the strength of the composites processed with lower SMEs was less than that observed on the 1 wt.% MWCNT reinforced PC composite. The elongation of the composites at maximum tensile strength were comparable to that of neat PC except for composites with 5 wt.% MWCNT loading processed with lower SMEs. Composites with identical filler loadings which were processed with higher SMEs showed higher notched impact strength values principally because of the ability of very well dispersed filler fractions to inhibit crack propagation. The significance of the

  2. The Cell Wall-Associated Proteins in the Dimorphic Pathogenic Species of Paracoccidioides.

    Science.gov (United States)

    Puccia, Rosana; Vallejo, Milene C; Longo, Larissa V G

    2017-01-01

    Paracoccidioides brasiliensis and P. lutzii cause human paracoccidioidomycosis (PCM). They are dimorphic ascomycetes that grow as filaments at mild temperatures up to 28oC and as multibudding pathogenic yeast cells at 37oC. Components of the fungal cell wall have an important role in the interaction with the host because they compose the cell outermost layer. The Paracoccidioides cell wall is composed mainly of polysaccharides, but it also contains proportionally smaller rates of proteins, lipids, and melanin. The polysaccharide cell wall composition and structure of Paracoccidioides yeast cells, filamentous and transition phases were studied in detail in the past. Other cell wall components have been better analyzed in the last decades. The present work gives to the readers a detailed updated view of cell wall-associated proteins. Proteins that have been localized at the cell wall compartment using antibodies are individually addressed. We also make an overview about PCM, the Paracoccidioides cell wall structure, secretion mechanisms, and fungal extracellular vesicles. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Structure of polysaccharide antibiotics

    International Nuclear Information System (INIS)

    Matutano, L.

    1966-01-01

    Study of the structure of antibiotics having two or several sugars in their molecule. One may distinguish: the polysaccharide antibiotics themselves, made up of two or several sugars either with or without nitrogen, such as streptomycin, neomycins, paromomycine, kanamycin, chalcomycin; the hetero-polysaccharide antibiotics made up of one saccharide part linked to an aglycone of various type through a glucoside: macrolide, pigment, pyrimidine purine. Amongst these latter are: erythromycin, magnamycin, spiramycin, oleandomycin, cinerubin and amicetin. The sugars can either play a direct role in biochemical reactions or act as a dissolving agent, as far as the anti-microbe power of these antibiotics is concerned. (author) [fr

  4. Seismic behavior and design of a primary shield structure consisting of steel-plate composite (SC) walls

    Energy Technology Data Exchange (ETDEWEB)

    Booth, Peter N., E-mail: boothpn@purdue.edu [Lyles School of Civil Engineering, Purdue University, W. Lafayette, IN (United States); Varma, Amit H., E-mail: ahvarma@purdue.edu [Lyles School of Civil Engineering, Purdue University, W. Lafayette, IN (United States); Sener, Kadir C., E-mail: ksener@purdue.edu [Lyles School of Civil Engineering, Purdue University, W. Lafayette, IN (United States); Mori, Kentaro, E-mail: kentaro_mori@mhi.co.jp [Mitsubishi Heavy Industries, Ltd, Kobe (Japan)

    2015-12-15

    This paper presents an analytical evaluation of the seismic behavior and design of a unique primary shield (PSW) structure consisting of steel-plate composite (SC) walls designed for a typical pressurized water reactor (PWR) nuclear power plant. Researchers in Japan have previously conducted a reduced (1/6th) scale test of a PSW structure to evaluate its seismic (lateral) load-deformation behavior. This paper presents the development and benchmarking of a detailed 3D nonlinear inelastic finite element (NIFE) model to predict the lateral load-deformation response and behavior of the 1/6th scale test structure. The PSW structure consists of thick SC wall segments with complex and irregular geometry that surround the central reactor vessel cavity. The wall segments have three layers of steel plates (one each on the interior and exterior surfaces and one embedded in the middle) that are anchored to the concrete infill with stud anchors. The results from the 3D NIFE analyses include: (i) the lateral load-deformation behavior of the PSW structure, (ii) the progression of yielding in the steel plates, concrete cracking, formation of compression struts, and (iii) the final failure mode. These results are compared and benchmarked using experimental measurements and observations reported by Shodo et al. (2003). The analytical results provide significant insight into the lateral behavior and strength of the PSW structure, and are used for developing a design approach. This design approach starts with ACI 349 code equations for reinforced concrete shear walls and modifies them for application to the PSW structure. A simplified 3D linear elastic finite element (LEFE) model of the PSW structure is also proposed as a conventional structural analysis tool for estimating the design force demands for various load combinations.

  5. Seismic behavior and design of a primary shield structure consisting of steel-plate composite (SC) walls

    International Nuclear Information System (INIS)

    Booth, Peter N.; Varma, Amit H.; Sener, Kadir C.; Mori, Kentaro

    2015-01-01

    This paper presents an analytical evaluation of the seismic behavior and design of a unique primary shield (PSW) structure consisting of steel-plate composite (SC) walls designed for a typical pressurized water reactor (PWR) nuclear power plant. Researchers in Japan have previously conducted a reduced (1/6th) scale test of a PSW structure to evaluate its seismic (lateral) load-deformation behavior. This paper presents the development and benchmarking of a detailed 3D nonlinear inelastic finite element (NIFE) model to predict the lateral load-deformation response and behavior of the 1/6th scale test structure. The PSW structure consists of thick SC wall segments with complex and irregular geometry that surround the central reactor vessel cavity. The wall segments have three layers of steel plates (one each on the interior and exterior surfaces and one embedded in the middle) that are anchored to the concrete infill with stud anchors. The results from the 3D NIFE analyses include: (i) the lateral load-deformation behavior of the PSW structure, (ii) the progression of yielding in the steel plates, concrete cracking, formation of compression struts, and (iii) the final failure mode. These results are compared and benchmarked using experimental measurements and observations reported by Shodo et al. (2003). The analytical results provide significant insight into the lateral behavior and strength of the PSW structure, and are used for developing a design approach. This design approach starts with ACI 349 code equations for reinforced concrete shear walls and modifies them for application to the PSW structure. A simplified 3D linear elastic finite element (LEFE) model of the PSW structure is also proposed as a conventional structural analysis tool for estimating the design force demands for various load combinations.

  6. At the border: the plasma membrane-cell wall continuum.

    Science.gov (United States)

    Liu, Zengyu; Persson, Staffan; Sánchez-Rodríguez, Clara

    2015-03-01

    Plant cells rely on their cell walls for directed growth and environmental adaptation. Synthesis and remodelling of the cell walls are membrane-related processes. During cell growth and exposure to external stimuli, there is a constant exchange of lipids, proteins, and other cell wall components between the cytosol and the plasma membrane/apoplast. This exchange of material and the localization of cell wall proteins at certain spots in the plasma membrane seem to rely on a particular membrane composition. In addition, sensors at the plasma membrane detect changes in the cell wall architecture, and activate cytoplasmic signalling schemes and ultimately cell wall remodelling. The apoplastic polysaccharide matrix is, on the other hand, crucial for preventing proteins diffusing uncontrollably in the membrane. Therefore, the cell wall-plasma membrane link is essential for plant development and responses to external stimuli. This review focuses on the relationship between the cell wall and plasma membrane, and its importance for plant tissue organization. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  7. Effects of Operating Temperature on Droplet Casting of Flexible Polymer/Multi-Walled Carbon Nanotube Composite Gas Sensors

    Directory of Open Access Journals (Sweden)

    Jin-Chern Chiou

    2016-12-01

    Full Text Available This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC, polyethylene oxide (PEO, and polyvinylpyrrolidone (PVP. Electrical characterization of impedance, sensing response magnitude, and scanning electron microscope (SEM morphology of each type of polymer/MWCNT composite film was performed at different operating temperatures. With respect to ethanol, the response magnitude of the sensor decreased with increasing operating temperatures. The results indicated that the higher operating temperature could reduce the response and influence the sensitivity of the polymer/MWCNT gas sensor array. The morphology of polymer/MWCNT composite films revealed that there were changes in the porous film after volatile organic compound (VOC testing.

  8. Gel spinning of PVA composite fibers with high content of multi-walled carbon nanotubes and graphene oxide hybrids

    International Nuclear Information System (INIS)

    Wei, Yizhe; Lai, Dengpan; Zou, Liming; Ling, Xinlong; Lu, Hongwei; Xu, Yongjing

    2015-01-01

    In this report, poly (vinyl alcohol) (PVA) composite fibers with high content of multi-walled carbon nanotubes and graphene oxide (MWCNTs-GO) hybrids were prepared by gel spinning, and were characterized by TGA, DSC, SEM, XL-2 yarn strength tester and electrical conductivity measurement. The total content of MWCNTs-GO hybrids in the PVA composite fibers, which is up to 25 wt%, was confirmed by TGA analysis. The DSC measurement shows that the melting and crystallization peaks decreased after the addition of nano-fillers. This is due to the reason that the motion of PVA chains is completely confined by strong hydrogen bonding interaction between PVA and nano-fillers. After the addtion of GO, the dispersibility of MWCNTs in composite fibers improved slightly. And the tensile strength and Young's modulus increased by 38% and 67%, respectively. This is caused by the increased hydrogen bonding interaction and synergistic effect through hybridization of MWCNTs and GO. More significantly, the electrical conductivity of PVA/MWCNTs/GO composite fibers enhanced by three orders of magnitude with the addition of GO. (paper)

  9. Nonlinear optical properties of polyaniline and poly (o-toluidine) composite thin films with multi walled carbon nano tubes

    Energy Technology Data Exchange (ETDEWEB)

    Nagaraja, K.K. [National University of Science and Technology “MISiS”, Leninskii pr. 4, Moscow 119049 (Russian Federation); Pramodini, S. [Department of Physics, School of Engineering and Technology, Jain University, Jakkasandra Post, Bengaluru 5621112, Karnataka (India); Poornesh, P., E-mail: poorneshp@gmail.com [Nonlinear Optics Research Laboratory, Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576 104, Karnataka (India); Telenkov, M.P. [National University of Science and Technology “MISiS”, Leninskii pr. 4, Moscow 119049 (Russian Federation); Kityk, I.V. [Electrical Engineering Department, Czestochowa University Technology, Czestochowa (Poland)

    2017-05-01

    We report the improved third-order nonlinear optical properties of polyaniline and poly (o-toluidine) with different doping concentrations of multi walled carbon nano tube (MWCNTs) composite thin films investigated using z-scan technique and continuous wave He–Ne laser at 633 nm wavelength was used as source of excitation. Thin films were prepared by spin coating technique on glass substrate. The structural properties of the composite films were analysed by X-ray diffraction studies and the characteristic peaks corresponding to MWCNTs and polymers have been observed. The surface morphology of the deposited films was analysed using scanning electron microscopy and it confirms that the polymer in the composites has been coated on the MWCNTs homogeneously. The z-scan results reveal that the films exhibit reverse saturable absorption and self-defocusing nonlinearity. The third-order nonlinear optical susceptibility χ{sup (3)} is found to be of the order of 10{sup −3} esu. Also, optical power limiting and clamping experiment was performed. The clamping values increases with increase in concentration and the lowest clamping observed for composite films are 1 mW and 0.7 mW.

  10. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Dong; Harkin-Jones, Eileen [School of Mechanical and Aerospace Engineering, Queen’s University Belfast, BT9 5AH (United Kingdom); Linton, David [School of Electronics, Electrical Engineering and Computer Science, Queen’s University Belfast, BT9 5AH (United Kingdom)

    2015-05-22

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1∼2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  11. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    International Nuclear Information System (INIS)

    Xiang, Dong; Harkin-Jones, Eileen; Linton, David

    2015-01-01

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1∼2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites

  12. Forage digestibility: the intersection of cell wall lignification and plant tissue anatomy

    Science.gov (United States)

    Cellulose and the other polysaccharides present in forage cell walls can be completely degraded by the rumen microflora but only when these polysaccharides have been isolated from the wall and all matrix structures eliminated. Understanding how cell wall component interactions limit microbial degrad...

  13. Poly(malachite green) at nafion doped multi-walled carbon nanotube composite film for simple aliphatic alcohols sensor.

    Science.gov (United States)

    Umasankar, Yogeswaran; Periasamy, Arun Prakash; Chen, Shen-Ming

    2010-01-15

    Conductive composite film which contains nafion (NF) doped multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold and indium tin oxide (ITO) electrodes by potentiostatic methods. The presence of MWCNTs in the composite film (MWCNTs-NF-PMG) enhances surface coverage concentration (Gamma) of PMG to approximately 396%, and increases the electron transfer rate constant (k(s)) to approximately 305%. Similarly, electrochemical quartz crystal microbalance study reveals the enhancement in the deposition of PMG at MWCNTs-NF film. The surface morphology of the composite film deposited on ITO electrode has been studied using scanning electron microscopy (SEM) and scanning tunneling microscopy (STM). These two techniques reveal that the PMG incorporated on MWCNTs-NF film. The MWCNTs-NF-PMG composite film also exhibits promising enhanced electrocatalytic activity towards the simple aliphatic alcohols such as methanol, ethanol and propanol. The electroanalytical responses of analytes at NF-PMG and MWCNTs-NF-PMG films were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electroanalytical studies, well defined voltammetric peaks have been obtained at MWCNTs-NF-PMG composite film for methanol, ethanol and propanol at Epa=609, 614 and 602mV respectively. The sensitivity of MWCNTs-NF-PMG composite film towards methanol, ethanol and propanol in CV technique are 0.59, 0.36 and 0.92microAmM(-1)cm(-2) respectively, which are higher than NF-PMG film. Further, the sensitivity values obtained using DPV are higher than the values obtained using CV technique.

  14. Polysaccharides from Traditional Chinese Medicines: Extraction, Purification, Modification, and Biological Activity

    Directory of Open Access Journals (Sweden)

    Yun Chen

    2016-12-01

    Full Text Available Traditional Chinese Medicine (TCM has been used to treat diseases in China for thousands of years. TCM compositions are complex, using as their various sources plants, animals, fungi, and minerals. Polysaccharides are one of the active and important ingredients of TCMs. Polysaccharides from TCMs exhibit a wide range of biological activities in terms of immunity- modifying, antiviral, anti-inflammatory, anti-oxidative, and anti-tumor properties. With their widespread biological activities, polysaccharides consistently attract scientist's interests, and the studies often concentrate on the extraction, purification, and biological activity of TCM polysaccharides. Currently, numerous studies have shown that the modification of polysaccharides can heighten or change the biological activities, which is a new angle of polysaccharide research. This review highlights the current knowledge of TCM polysaccharides, including their extraction, purification, modification, and biological activity, which will hopefully provide profound insights facilitating further research and development.

  15. Non-cellulosic polysaccharides from cotton fibre are differently impacted by textile processing

    DEFF Research Database (Denmark)

    Runavot, Jean-Luc; Guo, Xiaoyuan; Willats, William George Tycho

    2014-01-01

    -cellulosic cotton fibre polysaccharides during different steps of cotton textile processing using GC-MS, HPLC and comprehensive microarray polymer profiling to obtain monosaccharide and polysaccharide amounts and linkage compositions. Additionally, in situ detection was used to obtain information on polysaccharide......Cotton fibre is mainly composed of cellulose, although non-cellulosic polysaccharides play key roles during fibre development and are still present in the harvested fibre. This study aimed at determining the fate of non-cellulosic polysaccharides during cotton textile processing. We analyzed non...... localization and accessibility. We show that pectic and hemicellulosic polysaccharide levels decrease during cotton textile processing and that some processing steps have more impact than others. Pectins and arabinose-containing polysaccharides are strongly impacted by the chemical treatments, with most being...

  16. Polysaccharides from Traditional Chinese Medicines: Extraction, Purification, Modification, and Biological Activity.

    Science.gov (United States)

    Chen, Yun; Yao, Fangke; Ming, Ke; Wang, Deyun; Hu, Yuanliang; Liu, Jiaguo

    2016-12-13

    Traditional Chinese Medicine (TCM) has been used to treat diseases in China for thousands of years. TCM compositions are complex, using as their various sources plants, animals, fungi, and minerals. Polysaccharides are one of the active and important ingredients of TCMs. Polysaccharides from TCMs exhibit a wide range of biological activities in terms of immunity- modifying, antiviral, anti-inflammatory, anti-oxidative, and anti-tumor properties. With their widespread biological activities, polysaccharides consistently attract scientist's interests, and the studies often concentrate on the extraction, purification, and biological activity of TCM polysaccharides. Currently, numerous studies have shown that the modification of polysaccharides can heighten or change the biological activities, which is a new angle of polysaccharide research. This review highlights the current knowledge of TCM polysaccharides, including their extraction, purification, modification, and biological activity, which will hopefully provide profound insights facilitating further research and development.

  17. Multiparameter structural optimization of single-walled carbon nanotube composites: toward record strength, stiffness, and toughness.

    Science.gov (United States)

    Shim, Bong Sup; Zhu, Jian; Jan, Edward; Critchley, Kevin; Ho, Szushen; Podsiadlo, Paul; Sun, Kai; Kotov, Nicholas A

    2009-07-28

    Efficient coupling of mechanical properties of SWNTs with the matrix leading to the transfer of unique mechanical properties of SWNTs to the macroscopic composites is a tremendous challenge of today's materials science. The typical mechanical properties of known SWNT composites, such as strength, stiffness, and toughness, are assessed in an introductory survey where we focused on concrete numerical parameters characterizing mechanical properties. Obtaining ideal stress transfer will require fine optimization of nanotube-polymer interface. SWNT nanocomposites were made here by layer-by-layer (LBL) assembly with poly(vinyl alcohol) (PVA), and the first example of optimization in respect to key parameters determining the connectivity at the graphene-polymer interface, namely, degree of SWNT oxidation and cross-linking chemistry, was demonstrated. The resulting SWNT-PVA composites demonstrated tensile strength (σ(ult)) = 504.5 ± 67.3 MPa, stiffness (E) = 15.6 ± 3.8 GPa, and toughness (K) = 121.2 ± 19.2 J/g with maximum values recorded at σ(ult) = 600.1 MPa, E = 20.6 GPa, and K = 152.1 J/g. This represents the strongest and stiffest nonfibrous SWNT composites made to date outperforming other bulk composites by 2-10 times. Its high performance is attributed to both high nanotube content and efficient stress transfer. The resulting LBL composite is also one of the toughest in this category of materials and exceeding the toughness of Kevlar by 3-fold. Our observation suggests that the strengthening and toughening mechanism originates from the synergistic combination of high degree of SWNT exfoliation, efficient SWNT-PVA binding, crack surface roughening, and fairly efficient distribution of local stress over the SWNT network. The need for a multiscale approach in designing SWNT composites is advocated.

  18. Automated image segmentation and registration of vessel wall MRI for quantitative assessment of carotid artery vessel wall dimensions and plaque composition

    NARCIS (Netherlands)

    Klooster, Ronald van 't

    2014-01-01

    The main goal of this thesis was to develop methods for automated segmentation, registration and classification of the carotid artery vessel wall and plaque components using multi-sequence MR vessel wall images to assess atherosclerosis. First, a general introduction into atherosclerosis and

  19. Storage related changes of cell wall based dietary fiber components of broccoli (Brassica oleracea var. italica) stems.

    Science.gov (United States)

    Schäfer, Judith; Stanojlovic, Luisa; Trierweiler, Bernhard; Bunzel, Mirko

    2017-03-01

    Storage related changes in the cell wall composition potentially affect the texture of plant-based foods and the physiological effects of cell wall based dietary fiber components. Therefore, a detailed characterization of cell wall polysaccharides and lignins from broccoli stems was performed. Freshly harvested broccoli and broccoli stored at 20°C and 1°C for different periods of time were analyzed. Effects on dietary fiber contents, polysaccharide composition, and on lignin contents/composition were much more pronounced during storage at 20°C than at 1°C. During storage, insoluble dietary fiber contents of broccoli stems increased up to 13%. Storage related polysaccharide modifications include an increase of the portions of cellulose, xylans, and homogalacturonans and a decrease of the neutral pectic side-chains arabinans and galactans. Broccoli stem lignins are generally rich in guaiacyl units. Lignins from freshly harvested broccoli stems contain slightly larger amounts of p-hydroxyphenyl units than syringyl units. Syringyl units are predominantly incorporated into the lignin polymers during storage, resulting in increased acetyl bromide soluble lignin contents. NMR-based analysis of the interunit linkage types of broccoli stem lignins revealed comparably large portions of resinol structures for a guaiacyl rich lignin. Incorporation of syringyl units into the polymers over storage predominantly occurs through β-O-4-linkages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Electrospinning of food proteins and polysaccharides

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Boutrup Stephansen, Karen; Chronakis, Ioannis S.

    2017-01-01

    Nano-microfibrous structures of biopolymers with a wide range of compositions, morphologies, mechanical properties and bioactivities could be developed using electrospinning technology. This review focuses on the processing, properties, functionalization and potential applications of electrospun ...... biopolymers. Biopolymers include proteins (gelatin, collagen, elastin, silk, soy zein, gliadin, hordein, amaranth, casein, wheat, whey, marine sources proteins), and polysaccharides (chitosan, starch, alginate, cellulose and cellulose derivatives, pullulan, dextran, cyclodextrins)....

  1. All-solid-state flexible microsupercapacitors based on reduced graphene oxide/multi-walled carbon nanotube composite electrodes

    Science.gov (United States)

    Mao, Xiling; Xu, Jianhua; He, Xin; Yang, Wenyao; Yang, Yajie; Xu, Lu; Zhao, Yuetao; Zhou, Yujiu

    2018-03-01

    All-solid-state flexible microsupercapacitors have been intensely investigated in order to meet the rapidly growing demands for portable microelectronic devices. Herein, we demonstrate a facile, readily scalable and cost-effective laser induction process for preparing reduced graphene oxide/multi-walled carbon nanotube composite, which can be used as the interdigital electrodes in microsupercapacitors. The obtained composite exhibits high volumetric capacitance about 49.35 F cm-3, which is nearly 5 times higher than that of the pristine reduced graphene oxide film in aqueous 1.0 M H2SO4 solution (measured at a current density of 5 A cm-3 in a three-electrode testing). Additionally, an all-solid-state flexible microsupercapacitor employing these composite electrodes with PVA/H3PO4 gel electrolyte delivers high volumetric energy density of 6.47 mWh cm-3 at 10 mW cm-3 under the current density of 20 mA cm-3 as well as achieve excellent cycling stability retaining 88.6% of its initial value and outstanding coulombic efficiency after 10,000 cycles. Furthermore, the microsupercapacitors array connected in series/parallel can be easily adjusted to achieve the demands in practical applications. Therefore, this work brings a promising new candidate of prepare technologies for all-solid-state flexible microsupercapacitors as miniaturized power sources used in the portable and wearable electronics.

  2. Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types.

    Science.gov (United States)

    Kim, JunHee; You, Young-Chan

    2015-03-03

    A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs) reinforced with grid-type glass-fiber-reinforced polymer (GFRP) shear connectors. Two kinds of insulation-expanded polystyrene (EPS) and extruded polystyrene (XPS) with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation.

  3. Effectively enhanced load transfer by interfacial reactions in multi-walled carbon nanotube reinforced Al matrix composites

    International Nuclear Information System (INIS)

    Zhou, Weiwei; Yamaguchi, Tatsuya; Kikuchi, Keiko; Nomura, Naoyuki; Kawasaki, Akira

    2017-01-01

    The thermal expansion response of multi-walled carbon nanotube (MWCNT) reinforced Al matrix composites was employed to discuss the improvement of the load transfer at the interface between the MWCNTs and the Al matrix. An aluminum carbide (Al_4C_3) nanostructure at the end of the MWCNTs, incorporated in the Al matrix, was produced by appropriate heat-treatment. The stress contrast around the Al_4C_3 observed in the high-resolution transmission electron microscopy (HRTEM) image revealed the evidence of a trace of friction, which would lead to the enhancement of the anchor effect from the Al matrix. This anchor effect of Al_4C_3 may hinder the local interfacial slippage and constrain the deformation of the Al matrix. As a result, the thermal expansion behavior became linear and reversible under cyclic thermal load. It is concluded that the formation of Al_4C_3 could effectively enhance the load transfer in MWCNT/Al composites. The yield strength of MWCNT/Al composites was substantially increased under the appropriate quantity of Al_4C_3 produced at the MWCNT-Al interface by precisely controlled heat-treatment.

  4. Adaptation of polystyrene/multi-wall carbon nanotube composite properties in respect of its thermal stability

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Králová, Daniela; Lengálová, A.; Novotný, R.; Sáha, P.

    2010-01-01

    Roč. 31, č. 3 (2010), s. 452-458 ISSN 0272-8397 Institutional research plan: CEZ:AV0Z40500505 Keywords : electrical conductivity * polymer composites * miniemulsion polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.998, year: 2010

  5. A review of joining techniques for SiCf/SiC composites for first wall applications

    International Nuclear Information System (INIS)

    Lewinsohn, C.A.; Jones, R.H.

    1998-01-01

    Many methods for joining monolithic and composite silicon carbide are available. Three techniques are candidates for use in fusion energy systems: in-situ displacement reactions, pre-ceramic polymer adhesives, and reaction bonding. None of the methods are currently developed enough to satisfy all of the criteria required, i.e., low temperature fabrication, high strength, and radiation stability. 58 refs

  6. Composite materials for Tokamak wall armor, limiters, and beam dump applications

    International Nuclear Information System (INIS)

    Riley, R.E.; Wallace, T.C.; Dickinson, J.M.

    1979-01-01

    This paper describes materials which are composites of carbon fibers and low Z number carbides. The composite materials are fabricated by applying chemical vapor deposition (CVD) coats of either low Z number elements (i.e., boron, titanium, silicon, or nickel) or carbides (B 4 C, TiC, or SiC) onto graphite fibers, in the form of yarn, cloth, or three-dimensional structures, and then hot pressing the coated material to full density. The benefits of this approach are: (1) Each graphite filament (approx. 9 μm diameter) is surrounded by a refractory carbide which offers better resistance to erosion loss than graphite. If some material is spalled from the surface, the underlying graphite fibers are still coated, and thus still protected from hydrogen bombardment; (2) The composites should have longer thermal fatigue lives than carbides because of the graphite fiber reinforcement running through the composite; (3) Enhanced mechanical properties are obtained because of completely interconnected networks of carbide and graphite

  7. STUDY OF SINGLE WALLED CARBON NANOTUBE REINFORCED POLYMER COMPOSITES BY HANSEN SOLUBILITY PARAMETERS

    DEFF Research Database (Denmark)

    Ma, Jing

    reinforcement of the polymer by the addition of SWNTs. Existence of agglomerates, voids, and the lower glass transition temperature of epoxy resin, may give the negative effect on the mechanical properties of nanocomposite materials. In the design aspect of the composite material, HSP could help match SWNTs...

  8. Controlled nanostructure and high loading of single-walled carbon nanotubes reinforced polycarbonate composite

    International Nuclear Information System (INIS)

    Wang Shiren; Liang Zhiyong; Pham, Giang; Park, Young-Bin; Wang, Ben; Zhang, Chuck; Kramer, Leslie; Funchess, Percy

    2007-01-01

    This paper presents an effective technique to fabricate thermoplastic nanocomposites with high loading of well-dispersed single-walled carbon nanotubes (SWNTs). SWNT membranes were made from a multi-step dispersion and filtration method, and then impregnated with polycarbonate solution to make thermoplastic nanocomposites. High loading of nanotubes was achieved by controlling the viscosity of polycarbonate solution. SEM and AFM characterization results revealed the controlled nanostructure in the resultant nanocomposites. Dynamic mechanical property tests indicated that the storage modulus of the resulting nanocomposites at 20 wt% nanotubes loading was improved by a factor of 3.4 compared with neat polycarbonate material. These results suggest the developed approach is an effective way to fabricate thermoplastic nanocomposites with good dispersion and high SWNT loading

  9. Estimation of indigestible NDF in forages and concentrates from cell wall composition

    DEFF Research Database (Denmark)

    Krämer, Monika; Weisbjerg, Martin Riis; Lund, Peter

    2012-01-01

    within plant type, where INDF is defined as the portion of plant cell walls not digested after 288 h rumen incubation in Dacron bags with 12 μm pore size. INDF is one of the more important parameters determining the net energy (NE) value of a diet in some recently developed ruminant feed evaluation...... systems. Effects of maturity and cut number on INDF in three legumes and 18 grasses were determined based on an experiment in which each forage was cut at three times of primary growth and once in each of the following three regrowths. These data were supplemented with data from earlier experiments...... System (CNCPS) to predict INDF, averaging 2.6 for legumes, grains and grain byproducts, 2.7 for grasses and 1.0 for oilseeds including byproducts. The INDF/IOM ratio varied less among plant species within plant type than among plant types. Multiple linear regression analysis revealed higher INDF...

  10. Transmission electron microscopy, fluorescence microscopy, and confocal raman microscopic analysis of ultrastructural and compositional heterogeneity of Cornus alba L. wood cell wall.

    Science.gov (United States)

    Ma, Jianfeng; Ji, Zhe; Zhou, Xia; Zhang, Zhiheng; Xu, Feng

    2013-02-01

    Transmission electron microscopy (TEM), fluorescence microscopy, and confocal Raman microscopy can be used to characterize ultrastructural and compositional heterogeneity of plant cell walls. In this study, TEM observations revealed the ultrastructural characterization of Cornus alba L. fiber, vessel, axial parenchyma, ray parenchyma, and pit membrane between cells, notably with the ray parenchyma consisting of two well-defined layers. Fluorescence microscopy evidenced that cell corner middle lamella was more lignified than adjacent compound middle lamella and secondary wall with variation in lignification level from cell to cell. In situ Raman images showed that the inhomogeneity in cell wall components (cellulose and lignin) among different cells and within morphologically distinct cell wall layers. As the significant precursors of lignin biosynthesis, the pattern of coniferyl alcohol and aldehyde (joint abbreviation Lignin-CAA for both structures) distribution in fiber cell wall was also identified by Raman images, with higher concentration occurring in the fiber secondary wall where there was the highest cellulose concentration. Moreover, noteworthy was the observation that higher concentration of lignin and very minor amounts of cellulose were visualized in the pit membrane areas. These complementary microanalytical methods provide more accurate and complete information with regard to ultrastructural and compositional characterization of plant cell walls.

  11. An in vitro model of the glomerular capillary wall using electrospun collagen nanofibres in a bioartificial composite basement membrane.

    Directory of Open Access Journals (Sweden)

    Sadie C Slater

    Full Text Available The filtering unit of the kidney, the glomerulus, contains capillaries whose walls function as a biological sieve, the glomerular filtration barrier. This comprises layers of two specialised cells, glomerular endothelial cells (GEnC and podocytes, separated by a basement membrane. Glomerular filtration barrier function, and dysfunction in disease, remains incompletely understood, partly due to difficulties in studying the relevant cell types in vitro. We have addressed this by generation of unique conditionally immortalised human GEnC and podocytes. However, because the glomerular filtration barrier functions as a whole, it is necessary to develop three dimensional co-culture models to maximise the benefit of the availability of these cells. Here we have developed the first two tri-layer models of the glomerular capillary wall. The first is based on tissue culture inserts and provides evidence of cell-cell interaction via soluble mediators. In the second model the synthetic support of the tissue culture insert is replaced with a novel composite bioartificial membrane. This consists of a nanofibre membrane containing collagen I, electrospun directly onto a micro-photoelectroformed fine nickel supporting mesh. GEnC and podocytes grew in monolayers on either side of the insert support or the novel membrane to form a tri-layer model recapitulating the human glomerular capillary in vitro. These models will advance the study of both the physiology of normal glomerular filtration and of its disruption in glomerular disease.

  12. Research and tests of steel-concrete-steel sandwich composite shear wall in reactor containment of HTR-PM

    International Nuclear Information System (INIS)

    Sun Yunlun; Huang Wen; Zhang Ran; Zhang Pei; Tian Chunyu

    2014-01-01

    By quasi-static test of 8 specimens of steel-concrete-steel sandwich composite shear wall, the bearing capacity, hysteretic behavior, failure mode of the specimens was studied. So was the effect of the shear-span ratios, steel ratios and spacing of studs on the properties of the specimens. The failure patterns of all specimens with different shear-span ratios between 1.0 and 1.5 were compression-bending failure. The hysteretic curves of all specimens were relatively plump, which validated the well deformability and energy dissipation capacity of the specimens. When shear-span ratio less than 1.5, the shear property of the steel plate was well played, and so was the deformability of the specimens. The bigger the steel ratio was, the better the lateral resistance capacity and the deformability was. Among the spacing of studs in the test, the spacing of studs had no significant effect on the bearing capacity, deformability and ductility of the specimens. Based on the principle of superposition an advised formula for the compression-bending capacity of the shear wall was proposed, which fitted well with the test result and had a proper safety margin. (author)

  13. Analysis of interlaminar fracture toughness and damage mechanisms in composite laminates reinforced with sprayed multi-walled carbon nanotubes

    KAUST Repository

    Almuhammadi, Khaled; Alfano, Marco; Yang, Yang; Lubineau, Gilles

    2014-01-01

    The present work is focused on the nanoreinforcement of prepreg based carbon fiber composite laminates to improve delamination resistance. Functionalized multi-walled carbon nanotubes (MWCNTs) were dispersed over the interface between prepreg layers through solvent spraying and the resulting mode I interlaminar fracture toughness was determined. For comparison, baseline samples with neat prepregs were also prepared. Results indicate that the introduction of functionalized MWCNTs can favorably affect the interlaminar fracture toughness, and the associated mechanisms of failure have been investigated. The manufacturing procedures and the interfacial reinforcing mechanism were explored by analyzing (i) the wettability between CNTs-solvent solution and prepreg surface, (ii) CNTs dispersion and (iii) the fractured surfaces through high resolution scanning electron microscopy and Raman mapping. © 2013 Elsevier Ltd.

  14. Plant cell wall sugars: sweeteners for a bio-based economy.

    Science.gov (United States)

    Van de Wouwer, Dorien; Boerjan, Wout; Vanholme, Bartel

    2018-02-12

    Global warming and the consequent climate change is one of the major environmental challenges we are facing today. The driving force behind the rise in temperature is our fossil-based economy, which releases massive amounts of the greenhouse gas carbon dioxide into the atmosphere. In order to reduce greenhouse gas emission, we need to scale down our dependency on fossil resources, implying that we need other sources for energy and chemicals to feed our economy. Here, plants have an important role to play; by means of photosynthesis, plants capture solar energy to split water and fix carbon derived from atmospheric carbon dioxide. A significant fraction of the fixed carbon ends up as polysaccharides in the plant cell wall. Fermentable sugars derived from cell wall polysaccharides form an ideal carbon source for the production of bio-platform molecules. However, a major limiting factor in the use of plant biomass as feedstock for the bio-based economy is the complexity of the plant cell wall and its recalcitrance towards deconstruction. To facilitate the release of fermentable sugars during downstream biomass processing, the composition and structure of the cell wall can be engineered. Different strategies to reduce cell wall recalcitrance will be described in this review. The ultimate goal is to obtain a tailor-made biomass, derived from plants with a cell wall optimized for particular industrial or agricultural applications, without affecting plant growth and development. This article is protected by copyright. All rights reserved.

  15. Investigating Aspergillus nidulans secretome during colonisation of cork cell walls.

    Science.gov (United States)

    Martins, Isabel; Garcia, Helga; Varela, Adélia; Núñez, Oscar; Planchon, Sébastien; Galceran, Maria Teresa; Renaut, Jenny; Rebelo, Luís P N; Silva Pereira, Cristina

    2014-02-26

    Cork, the outer bark of Quercus suber, shows a unique compositional structure, a set of remarkable properties, including high recalcitrance. Cork colonisation by Ascomycota remains largely overlooked. Herein, Aspergillus nidulans secretome on cork was analysed (2DE). Proteomic data were further complemented by microscopic (SEM) and spectroscopic (ATR-FTIR) evaluation of the colonised substrate and by targeted analysis of lignin degradation compounds (UPLC-HRMS). Data showed that the fungus formed an intricate network of hyphae around the cork cell walls, which enabled polysaccharides and lignin superficial degradation, but probably not of suberin. The degradation of polysaccharides was suggested by the identification of few polysaccharide degrading enzymes (β-glucosidases and endo-1,5-α-l-arabinosidase). Lignin degradation, which likely evolved throughout a Fenton-like mechanism relying on the activity of alcohol oxidases, was supported by the identification of small aromatic compounds (e.g. cinnamic acid and veratrylaldehyde) and of several putative high molecular weight lignin degradation products. In addition, cork recalcitrance was corroborated by the identification of several protein species which are associated with autolysis. Finally, stringent comparative proteomics revealed that A. nidulans colonisation of cork and wood share a common set of enzymatic mechanisms. However the higher polysaccharide accessibility in cork might explain the increase of β-glucosidase in cork secretome. Cork degradation by fungi remains largely overlook. Herein we aimed at understanding how A. nidulans colonise cork cell walls and how this relates to wood colonisation. To address this, the protein species consistently present in the secretome were analysed, as well as major alterations occurring in the substrate, including lignin degradation compounds being released. The obtained data demonstrate that this fungus has superficially attacked the cork cell walls apparently by

  16. Dye-sensitized solar cells based on anatase TiO2/multi-walled carbon nanotubes composite nanofibers photoanode

    International Nuclear Information System (INIS)

    Du, Pingfan; Song, Lixin; Xiong, Jie; Li, Ni; Wang, Lijun; Xi, Zhenqiang; Wang, Naiyan; Gao, Linhui; Zhu, Hongliang

    2013-01-01

    Highlights: ► TiO 2 /multi-walled carbon nanotubes (MWCNTs) hybrid nanofibers are prepared via electrospinning. ► Dye-sensitized solar cells (DSSCs) are assembled using TiO 2 /MWCNTs nanofibers film as photoanode. ► Energy conversion efficiency of DSSCs is greatly dependent on the content of MWCNTs. ► Moderate MWCNTs incorporation can substantially enhance the performance of DSSCs. - Abstract: Anatase TiO 2 /multi-walled carbon nanotubes (TiO 2 /MWCNTs) hybrid nanofibers (NFs) film was prepared via a facile electrospinning method. Dye-sensitized solar cells (DSSCs) based on TiO 2 /MWCNTs composite NFs photoanodes with different contents of MWCNTs (0, 0.1, 0.3, 0.5, 1 wt.%) were assembled using N719 dye as sensitizer. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Raman spectrometer were used to characterize the TiO 2 /MWCNTs electrode films. The photocurrent–voltage (I–V) characteristic, incident photo-to-current conversion efficiency (IPCE) spectrum, and electrochemical impedance spectroscopy (EIS) measurements were carried out to evaluate the photoelectric properties of the DSSCs. The results reveal that the energy conversion efficiency is greatly dependent on the content of MWCNTs in the composite NFs film, and a moderate incorporation of MWCNTs can substantially enhance the performance of DSSCs. When the electrode contains 0.3 wt.% MWCNTs, the corresponding solar cell yield the highest efficiency of 5.63%. This efficiency value is approximately 26% larger than that of the unmodified counterpart.

  17. Multi-walled carbon nanotubes/polymer composites in absence and presence of acrylic elastomer (ACM).

    Science.gov (United States)

    Kumar, S; Rath, T; Mahaling, R N; Mukherjee, M; Khatua, B B; Das, C K

    2009-05-01

    Polyetherimide/Multiwall carbon nanotube (MWNTs) nanocomposites containing as-received and modified (COOH-MWNT) carbon nanotubes were prepared through melt process in extruder and then compression molded. Thermal properties of the composites were characterized by thermo-gravimetric analysis (TGA). Field emission scanning electron microscopy (FESEM) images showed that the MWNTs were well dispersed and formed an intimate contact with the polymer matrix without any agglomeration. However the incorporation of modified carbon nanotubes formed fascinating, highly crosslinked, and compact network structure throughout the polymer matrix. This showed the increased adhesion of PEI with modified MWNTs. Scanning electron microscopy (SEM) also showed high degree of dispersion of modified MWNTs along with broken ends. Dynamic mechanical analysis (DMA) results showed a marginal increase in storage modulus (E') and glass transition temperature (T(g)) with the addition of MWNTs. Increase in tensile strength and impact strength of composites confirmed the use the MWNTs as possible reinforcement agent. Both thermal and electrical conductivity of composites increased, but effect is more pronounced on modification due to formation of network of carbon nanotubes. Addition of acrylic elastomer to developed PEI/MWNTs (modified) nanocomposites resulted in the further increase in thermal and electrical properties due to the formation of additional bond between MWNTs and acrylic elastomers at the interface. All the results presented are well corroborated by SEM and FESEM studies.

  18. Dynamic mechanical analysis of multi-walled carbon nanotube/HDPE composites.

    Science.gov (United States)

    Kanagaraj, S; Guedes, R M; Oliveira, Mónica S A; Simões, José A O

    2008-08-01

    Since the discovery of carbon nanotubes (CNTs), their remarkable properties make them ideal candidates to reinforce in advanced composites. In this attempt, an enhancement of mechanical properties of high density polyethylene (HDPE) by adding 1 wt% of CNTs is studied using Dynamic mechanical and Thermal analyzer (DMTA). The chemically treated and functionalized CNTs were homogeneously dispersed with HDPE and the test samples were made using injection molding machine. Using DMTA, storage modulus (E'), loss modulus (E") and damping factor (tan delta) of the sample under oscillating load were studied as a function of frequency of oscillation and temperatures. The storage modulus decreases with an increase of temperature and increases by adding CNTs in the composites where the reinforcing effect of CNT is confirmed. It is concluded that the large scale polymer relaxations in the composites are effectively restrained by the presence of CNTs and thus the mechanical properties of nanocomposites increase. The transition frequency of loss modulus is observed at 1 Hz. The loss modulus decreases with an increase of temperature at below 1 Hz but opposite trend was observed at above 1 Hz. The shift factor could be predicted from Williams-Landel-Ferry (WLF) model which has good agreement with experimental results.

  19. Thin-walled composite tubes using fillers subjected to quasistatic axial compression

    International Nuclear Information System (INIS)

    AL-Qrimli, Haidar F; Mahdi, Fadhil A; Ismail, Firas B; Alzorqi, Ibrahim S

    2015-01-01

    It has been demonstrated that composites are lightweight, fatigue resistant and easily melded, a seemingly attractive alternative to metals. However, there has been no widespread switch from metals to composites in the automotive sector. This is because there are a number of technical issues relating to the use of composite materials that still need to be resolved including accurate material characterization, manufacturing and joining process. The total of 36 specimens have been fabricated using the fibre-glass and resin (epoxy) with a two different geometries (circular and corrugated) each one will be filled with five types of filler (Rice Husk, Wood Chips, Aluminium Chips, Coconut Fibre, Palm Oil Fibre) all these type will be compared with empty Tubes for circular and corrugated in order to comprehend the crashworthiness parameters (initial failure load, average load, maximum crushing load, load ratio, energy absorption, specific energy absorption, volumetric energy absorption, crushing force efficiency and crush strain relation) which are considered very sufficient parameters in the design of automotive industry parts. All the tests have been done using the “INSTRON Universal machine” which is computerized in order to simply give a high precision to the collection of the results, along with the use of quasi-static load to test and observe the behaviour of the fabricated specimens. (paper)

  20. Thin-walled composite tubes using fillers subjected to quasistatic axial compression

    Science.gov (United States)

    AL-Qrimli, Haidar F.; Mahdi, Fadhil A.; Ismail, Firas B.; Alzorqi, Ibrahim S.

    2015-04-01

    It has been demonstrated that composites are lightweight, fatigue resistant and easily melded, a seemingly attractive alternative to metals. However, there has been no widespread switch from metals to composites in the automotive sector. This is because there are a number of technical issues relating to the use of composite materials that still need to be resolved including accurate material characterization, manufacturing and joining process. The total of 36 specimens have been fabricated using the fibre-glass and resin (epoxy) with a two different geometries (circular and corrugated) each one will be filled with five types of filler (Rice Husk, Wood Chips, Aluminium Chips, Coconut Fibre, Palm Oil Fibre) all these type will be compared with empty Tubes for circular and corrugated in order to comprehend the crashworthiness parameters (initial failure load, average load, maximum crushing load, load ratio, energy absorption, specific energy absorption, volumetric energy absorption, crushing force efficiency and crush strain relation) which are considered very sufficient parameters in the design of automotive industry parts. All the tests have been done using the “INSTRON Universal machine” which is computerized in order to simply give a high precision to the collection of the results, along with the use of quasi-static load to test and observe the behaviour of the fabricated specimens.

  1. Comparison of Polysaccharides from Two Species of Ganoderma

    Directory of Open Access Journals (Sweden)

    Yu-Ping Tang

    2012-01-01

    Full Text Available Ganoderma lucidum and Ganoderma sinense, known as Lingzhi in Chinese, are commonly used Chinese medicines with excellent beneficial health effects. Triterpenes and polysaccharides are usually considered as their main active components. However, the content of triterpenes differs significantly between the two species of Ganoderma. To date, a careful comparison of polysaccharides from the two species of Ganoderma has not been performed. In this study, polysaccharides from fruiting bodies of two species of Lingzhi collected from different regions of China were analyzed and compared based on HPSEC-ELSD and HPSEC-MALLS-RI analyses, as well as enzymatic digestion and HPTLC of acid hydrolysates. The results indicated that both the HPSEC-ELSD profiles and the molecular weights of the polysaccharides were similar. Enzymatic digestion showed that polyshaccharides from all samples of Lingzhi could be hydrolyzed by pectinase and dextranase. HPTLC profiles of their TFA hydrolysates colored with different reagents and their monosaccharides composition were also similar.

  2. Detection of Inulin, a Prebiotic Polysaccharide, in Maple Syrup.

    Science.gov (United States)

    Sun, Jiadong; Ma, Hang; Seeram, Navindra P; Rowley, David C

    2016-09-28

    Maple syrup is a widely consumed plant-derived natural sweetener produced by concentrating xylem sap collected from certain maple (Acer) species. During thermal evaporation of water, natural phytochemical components are concentrated in maple syrup. The polymeric components from maple syrup were isolated by ethanol precipitation, dialysis, and anion exchange chromatography and structurally characterized by glycosyl composition analysis, glycosyl linkage analysis, and nuclear magnetic resonance spectroscopy. Among the maple syrup polysaccharides, one neutral polysaccharide was characterized as inulin with a broad molecular weight distribution, representing the first isolation of this prebiotic carbohydrate from a xylem sap. In addition, two acidic polysaccharides with structural similarity were identified as arabinogalactans derived from rhamnogalacturonan type I pectic polysaccharides.

  3. Highly transparent and conductive thin films fabricated with nano-silver/double-walled carbon nanotube composites.

    Science.gov (United States)

    Lee, Shie-Heng; Teng, Chih-Chun; Ma, Chen-Chi M; Wang, Ikai

    2011-12-01

    This study develops a technique for enhancing the electrical conductivity and optical transmittance of transparent double-walled carbon nanotube (DWNT) film. Silver nanoparticles were modified with a NH(2)(CH(2))(2)SH self-assembled monolayer terminated by amino groups and subsequent surface condensation that reacted with functionalized DWNTs. Ag nanoparticles were grafted on the surface of the DWNTs. The low sheet resistance of the resulting thin conductive film on a polyethylene terephthalate (PET) substrate was due to the increased contact areas between DWNTs and work function by grafting Ag nanoparticles on the DWNT surfaces. Increasing the contact area between DWNTs and work function improved the conductivity of the DWNT-Ag thin films. The prepared DWNT-Ag thin films had a sheet resistance of 53.4 Ω/sq with 90.5% optical transmittance at a 550 nm wavelength. After treatment with HNO(3) and annealing at 150 °C for 30 min, a lower sheet resistance of 45.8 Ω/sq and a higher transmittance of 90.4% could be attained. The value of the DC conductivity to optical conductivity (σ(DC)/σ(OP)) ratio is 121.3. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Cell wall composition contributes to the control of transpiration efficiency in Arabidopsis thaliana.

    Science.gov (United States)

    Liang, Yun-Kuan; Xie, Xiaodong; Lindsay, Shona E; Wang, Yi Bing; Masle, Josette; Williamson, Lisa; Leyser, Ottoline; Hetherington, Alistair M

    2010-11-01

    To identify loci in Arabidopsis involved in the control of transpirational water loss and transpiration efficiency (TE) we carried out an infrared thermal imaging-based screen. We report the identification of a new allele of the Arabidopsis CesA7 cellulose synthase locus designated AtCesA7(irx3-5) involved in the control of TE. Leaves of the AtCesA7(irx3-5) mutant are warmer than the wild type (WT). This is due to reduced stomatal pore widths brought about by guard cells that are significantly smaller than the WT. The xylem of the AtCesA7(irx3-5) mutant is also partially collapsed, and we suggest that the small guard cells in the mutant result from decreased water supply to the developing leaf. We used carbon isotope discrimination to show that TE is increased in AtCesA7(irx3-5) when compared with the WT. Our work identifies a new class of genes that affects TE and raises the possibility that other genes involved in cell wall biosynthesis will have an impact on water use efficiency. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.

  5. Brazed graphite/refractory metal composites for first-wall protection elements

    Science.gov (United States)

    Šmid, I.; Croessmann, C. D.; Salmonson, J. C.; Whitley, J. B.; Kny, E.; Reheis, N.; Kneringer, G.; Nickel, H.

    1991-03-01

    The peak surface heat flux deposition on divertor elements of near term fusion devices is expected to exceed 10 MW/m 2. The needed reliability of brazed plasma interactive components, particularly under abnormal operating conditions with peak surface temperatures well beyond 1000°C, makes refractory metallic substrates and brazes with a high melting point very attractive. TZM, a high temperature alloy of molybdenum, and isotropic graphite, materials very closely matched in their thermal expansion, were brazed with four high-temperature brazes. The brazes used were Zr, 90Ni/10Ti, 90Cu/10Ti and 70Ag/27Cu/3Ti (nominal composition prior to brazing, wt%). The resulting composite tiles of 50 × 50 mm2 with a TZM thickness of 5 mm and a graphite thickness of 10 mm have been tested in high heat flux simulation for their thermal fatigue properties. Up to 600 loading cycles were carried out with an average heat flux of 10 MW/m 2 for 0.5 s pulses. The maximum surface temperature was 1100°C. In support of the experiment, the thermal response and temperature gradients of the samples were investigated using a finite element model.

  6. Brazed graphite/refractory metal composites for first-wall protection elements

    International Nuclear Information System (INIS)

    Smid, I.; Croessmann, C.D.; Salmonson, J.C.; Whitley, J.B.; Nickel, H.

    1991-01-01

    The peak surface heat flux deposition on divertor elements of near term fusion devices is expected to exceed 10 MW/m 2 . The needed reliability of brazed plasma interactive components, particularly under abnormal operating conditions with peak surface temperatures well beyond 1000deg C, makes refractory metallic substrates and brazes with a high melting point very attractive. TZM, a high temperature alloy of molybdenum, and isotropic graphite, materials very closely matched in their thermal expansion, were brazed with four high-temperature brazes. The brazes used were Zr, 90Ni/10Ti, 90Cu/10Ti and 70Ag/27Cu/3Ti (nominal composition prior to brazing, wt%). The resulting composite tiles of 50x50 mm 2 with a TZM thickness of 5 mm and a graphite thickness of 10 mm have been tested in high heat flux simulation for their thermal fatigue properties. Up to 600 loading cycles were carried out with an average heat flux of 10 MW/m 2 for 0.5 s pulses. The maximum surface temperature was 1100deg C. In support of the experiment, the thermal response and temperature gradients of the samples were investigated using a finite element model. (orig.)

  7. Brazed graphite/refractory metal composites for first-wall protection elements

    International Nuclear Information System (INIS)

    Smid, I.; Croessmann, C. D.; Salmonson, J. C.; Whitley, J. B.; Kny, E.; Reheis, N.; Kneringer, G.; Nickel, H.

    1995-01-01

    The peak surface heat flux deposition on divertor elements of near term fusion devices is expected to exceed 10 MW/m 2 . The needed reliability of brazed plasma interactive components, particularly under abnormal operating conditions with peak surface temperatures well beyond 1000 degree C, makes refractory metallic substrates and brazes with a high melting point very attractive. TZM, a high temperature alloy of molybdenum, and isotropic graphite, materials very closely matched in their thermal expansion, were brazed with four high-temperature brazes. The brazes used were Zr, 90Ni/10Ti, 90Cu/10Ti and 70Ag/27Cu/3Ti (nominal composition prior to brazing, wt%). The resulting composite tiles of 5O X 50 mm 2 with a TZM thickness of 5 mm and a graphite thickness of 10 mm have been tested in high heat flux simulation for their thermal fatigue properties. Up to 600 loading cycles were carried out with an average heat flux of 10 MW/m 2 for 0.5 s pulses. The maximum surface temperature was 1100 degree C. In support of the experiment, the thermal response and temperature gradients of the samples were investigated using a finite element model. (author)

  8. Brazed graphite/refractory metal composites for first wall protection elements

    International Nuclear Information System (INIS)

    Smid, I.; Croessmann, C. D.; Salmonson, J. C.; Whitley, J. B.; Kny, E.; Reheis, N; Kneringer, G.; Nickel, H.

    1995-01-01

    The peak surface heat flux deposition on divertor elements of near term fusion devices is expected to exceed 10 MW/m 2 . The needed reliability of brazed plasma interactive components, particularly under abnormal operating conditions with peak surface temperatures well beyond 1000 degree C, makes refractory metallic substrates and brazes with a high melting point very attractive. TZM, a high temperature alloy of molybdenum, and isotropic graphite, materials very closely matched in their thermal expansion, were brazed with four high-temperature brazes. The brazes used were Zr, 90Ni/10Ti, 90Cu/10Ti and 70Ag/27Cu/10Ti (nominal composition prior to brazing, wt%). The resulting composite tiles of 50 x 50 mm with a TZM thickness of 5 mm and a graphite thickness of 10 mm have been tested in high heat flux simulation for their thermal fatigue properties. Up to 600 loading cycles were carried out with the experimental parameters chosen to cover NET/ITER design specifications. In support of the experiment, the thermal response and temperature gradients of the samples were investigated using a finite element model. (author)

  9. Industrially synthesized single-walled carbon nanotubes: compositional data for users, environmental risk assessments, and source apportionment

    Energy Technology Data Exchange (ETDEWEB)

    Plata, D L; Gschwend, P M [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Reddy, C M [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 (United States)], E-mail: dplata@whoi.edu

    2008-05-07

    Commercially available single-walled carbon nanotubes (SWCNTs) contain large percentages of metal and carbonaceous impurities. These fractions influence the SWCNT physical properties and performance, yet their chemical compositions are not well defined. This lack of information also precludes accurate environmental risk assessments for specific SWCNT stocks, which emerging local legislation requires of nanomaterial manufacturers. To address these needs, we measured the elemental, molecular, and stable carbon isotope compositions of commercially available SWCNTs. As expected, catalytic metals occurred at per cent levels (1.3-29%), but purified materials also contained unexpected metals (e.g., Cu, Pb at 0.1-0.3 ppt). Nitrogen contents (up to 0.48%) were typically greater in arc-produced SWCNTs than in those derived from chemical vapor deposition. Toluene-extractable materials contributed less than 5% of the total mass of the SWCNTs. Internal standard losses during dichloromethane extractions suggested that metals are available for reductive dehalogenation reactions, ultimately resulting in the degradation of aromatic internal standards. The carbon isotope content of the extracted material suggested that SWCNTs acquired much of their carbonaceous contamination from their storage environment. Some of the SWCNTs, themselves, were highly depleted in {sup 13}C relative to petroleum-derived chemicals. The distinct carbon isotopic signatures and unique metal 'fingerprints' may be useful as environmental tracers allowing assessment of SWCNT sources to the environment.

  10. Enhanced electrical conductivity and hardness of silver-nickel composites by silver-coated multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Lee, Dongmok; Sim, Jeonghyun; Baik, Seunghyun; Kim, Wonyoung; Moon, Chuldong; Cho, Wookdong

    2015-01-01

    We investigated electrical conductivity and Vickers hardness of Ag- and Ni-based composites prepared by powder metallurgy involving spark plasma sintering. The starting composition was Ag:Ni = 61:39 vol%, which provided an electrical conductivity of 3.30 × 10"5 S cm"−"1 and a hardness of 1.27 GPa. The addition of bare multi-walled carbon nanotubes (MWNTs, 1.45 vol%) increased hardness (1.31 GPa) but decreased electrical conductivity (2.99 × 10"5 S cm"−"1) and carrier mobility (11 cm"2 V"−"1 s"−"1) due to the formation of Ni_3C in the interface between the MWNTs and Ni during spark plasma sintering. The formation of Ni_3C was prevented by coating the surface of the nanotubes with Ag (nAgMWNTs), concomitantly increasing electrical conductivity (3.43 × 10"5 S cm"−"1) and hardness (1.37 GPa) of the sintered specimen (Ag:Ni:nAgMWNTs = 59.55:39:1.45 vol%). The electrical contact switching time (133 357) was also increased by 30%, demonstrating excellent feasibility as electrical contact materials for electric power industries. (paper)

  11. Colony variation of Helicobacter pylori: pathogenic potential is correlated to cell wall lipid composition.

    Science.gov (United States)

    Bukholm, G; Tannaes, T; Nedenskov, P; Esbensen, Y; Grav, H J; Hovig, T; Ariansen, S; Guldvog, I

    1997-05-01

    Differences in expression of disease after infection with Helicobacter pylori have so far been connected with host factors and bacterial interstrain variation. In this study, spontaneous and ecology-mediated intrastrain variation was examined. Four clinical isolates of H. pylori were shown to give rise to two colony forms. Bacterial morphology was examined by electron microscopy. Bacterial fractions were examined for proteins using ion exchange chromatography and SDS-PAGE; for lipids using thin-layer chromatography, lipid anion-exchange chromatography, column chromatography on silica gel, 31P-NMR, gas chromatography and mass spectrometry. Bacterial in vitro invasiveness and adhesiveness were examined in two different systems, and urease and VacA toxin were assayed by Western blot analysis. H. pylori was shown to give rise to two colony forms: at normal pH the population was dominated by L colonies. One strain was chosen for further studies. Bacteria from L colonies retained VacA toxin and urease, did not invade or adhere to epithelial cells, and contained normal quantities of phosphatidylethanolamine. In a small frequency, spontaneous S colonies were formed. Bacteria from these colonies released VacA and urease, adhered to and invaded epithelial cells and contained increased amounts of lysophosphatidyl ethanolamine and phosphatidyl serine. After addition of HCl to the culture medium (pH6), almost only S colonies were formed. The results demonstrate that environmental factors, such as HCl, can change the bacterial cell wall, and thereby enhance expression of virulence factors of H. pylori in vitro. A similar in vivo variation would have implications for our understanding of the interaction between HCl secretion in the gastric mucosa and H. pylori in the development of peptic ulcer disease.

  12. Development of a photoelectrochemical lactic dehydrogenase biosensor using multi-wall carbon nanotube-TiO2 nanoparticle composite as coenzyme regeneration tool

    International Nuclear Information System (INIS)

    Liu, Xiaoqiang; Yan, Rui; Zhu, Jie; Huo, Xiaohe; Wang, Xinhai

    2015-01-01

    Highlights: •Multi-wall Carbon Nanotube-TiO 2 nanoparticle composite was synthesized by hydrothermal method •The composite was characterized by TEM, XRD, FT-IR •A photoelectrochemical (PEC) lactic dehydrogenase (LDH) biosensor was developed based on the composite •The composite acts as both coenzyme regeneration tool and immobilization material •The PEC biosensor shows superiority over the electrochemical LDH biosensors in analytical performance -- Abstract: A novel photoelectrochemical (PEC) lactic dehydrogenase (LDH) biosensor was developed based on a multi-wall carbon nanotube (MWCNT)-TiO 2 nanoparticle (TNP) composite platform. This composite platform can not only aid in regeneration of nicotinamide adenine dinucleotide (NAD + ) in the enzymatic cycle, but also immobilize enzymes on electrode surface. TNPs were grown on MWCNT surface through a hydrothermal method and the composite was characterized by various spectroscopic techniques. The electrochemical performance of the LDH biosensors has demonstrated that the composite is a feasible immobilization matrix for LDH. The PEC experiments have confirmed that NAD + can be regenerated by the holes produced by irradiating MWCNT-TNP composite to fulfill the enzyme catalytic cycle. The analytical performance of the PEC LDH biosensor was studied by measuring its photocurrents. The dynamic range, sensitivity and limit of detection of the biosensor were estimated to be 0.5 to 120 μM, 0.0242 μA μM −1 and 0.1 μM respectively, which are superior to those of electrochemical LDH biosensors

  13. Investigation on Nano composite Membrane of Multi walled Carbon Nano tube Reinforced Polycarbonate Blend for Gas Separation

    International Nuclear Information System (INIS)

    Kausar, A.

    2016-01-01

    Carbon nano tube has been explored as a nano filler in high performance polymeric membrane for gas separation. In this regard, nano composite membrane of polycarbonate (PC), poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHFP), and multi walled carbon nano tube (MWCNT) was fabricated via phase inversion technique. Poly (ethylene glycol) (PEG) was employed for the compatibilization of the blend system. Two series of PC/PVFHFP/PEG were developed using purified P-MWCNT and acid functional A-MWCNT nano filler. Scanning and transmission electron micrographs have shown fine nano tube dispersion and wetting by matrix, compared with the purified system. Tensile strength and Young s modulus of PC/PVFHFP/PEG/MWCNT-A 1-5 were found to be in the range of 63.6-72.5 MPa and 110.6-122.1 MPa, respectively. The nano composite revealed 51% increase in Young s modulus and 28% increase in tensile stress relative to the pristine blend. The A-MWCNT was also effective in enhancing the perm selectivity αCO 2 /N 2 (31.2-39.9) of nano composite membrane relative to the blend membrane (21.6). The permeability ρCO 2 of blend was 125.6 barrer; however, the functional series had enhancedρCO 2 values ranging from 142.8 to 186.6 barrer. Moreover, A-MWCNT loading improved the gas diffusivity of PC/PVFHFP/PEG/MWCNT-A 1-5; however, filler content did not significantly influence the CO 2 and N 2 solubility.

  14. Multi-walled carbon nanotubes/graphene oxide hybrid and nanohydroxyapatite composite: A novel coating to prevent dentin erosion.

    Science.gov (United States)

    Nahorny, Sídnei; Zanin, Hudson; Christino, Vinie Abreu; Marciano, Fernanda Roberta; Lobo, Anderson Oliveira; Soares, Luís Eduardo Silva

    2017-10-01

    To date is emergent the development of novel coatings to protect erosion, especially to preventive dentistry and restorative dentistry. Here, for the first time we report the effectiveness of multi-walled carbon nanotube/graphene oxide hybrid carbon-base material (MWCNTO-GO) combined with nanohydroxyapatite (nHAp) as a protective coating for dentin erosion. Fourier transform Raman spectroscopy (FT-Raman), scanning electron (SEM), and transmission electron (TEM) microscopy were used to investigated the coatings and the effect of acidulated phosphate fluoride gel (APF) treatment on bovine teeth root dentin before and after erosion. The electrochemical corrosion performance of the coating was evaluated. Raman spectra identified that: (i) the phosphate (ν 1 PO 4 3- ) content of dentin was not significantly affected by the treatments and (ii) the carbonate (ν 1 CO 3 2- ) content in dentin increased when nHAp was used. However, the nHAp/MWCNTO-GO composite exposited lower levels of organic matrix (CH bonds) after erosion compared to other treatments. Interesting, SEM micrographs identified that the nHAp/MWCNTO-GO formed layers after erosive cycling when associate with APF treatment, indicating a possible chemical bond among them. Treatments of root dentin with nHAp, MWCNTO-GO, APF_MWCNTO-GO, and APF_nHAp/MWCNTO-GO increased the carbonate content, carbonate/phosphate ratio, and organic matrix band area after erosion. The potentiodynamic polarization curves and Nyquist plot showed that nHAp, MWCNT-GO and nHAp/MWCNT-GO composites acted as protective agents against corrosion process. Clearly, the nHAp/MWCNTO-GO composite was stable after erosive cycling and a thin and acid-resistant film was formed when associated to APF treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Steel-plate composite (SC) walls for safety related nuclear facilities: Design for in-plane forces and out-of-plane moments

    International Nuclear Information System (INIS)

    Varma, Amit H.; Malushte, Sanjeev R.; Sener, Kadir C.; Lai, Zhichao

    2014-01-01

    Steel-concrete (SC) composite walls being considered and used as an alternative to conventional reinforced concrete (RC) walls in safety-related nuclear facilities due to their construction economy and structural efficiency. However, there is a lack of standardized codes for SC structures, and design guidelines and approaches are still being developed. This paper presents the development and verification of: (a) mechanics based model, and (b) detailed nonlinear finite element model for predicting the behavior and failure of SC wall panels subjected to combinations of in-plane forces. The models are verified using existing test results, and the verified models are used to explore the behavior of SC walls subjected to combinations of in-plane forces and moments. The results from these investigations are used to develop an interaction surface in principle force (S p1 –S p2 ) space that can be used to design or check the adequacy of SC wall panels. The interaction surface is easy to develop since it consists of straight line segments connecting anchor points defined by the SC wall section strengths in axial tension, in-plane shear, and compression. Both models and the interaction surface (for design) developed in this paper are recommended for future work. However, in order to use these approaches, the SC wall section should be detailed with adequate shear connector and tie bar strength and spacing to prevent non-ductile failure modes

  16. Experimental thermal study and numerical simulation of a composite solar wall. Optimization of the energetic performances; Etude thermique experimentale et simulation numerique d`un mur solaire composite. Optimisation des performances energetiques

    Energy Technology Data Exchange (ETDEWEB)

    Zalewski, L.

    1996-11-27

    The objective of this work is the analysis of a passive solar component: the composite solar wall, a building component, which includes an insulating panel located behind the massive wall. This panel has two vents located at the top and at the bottom, which allow the air to circulate from the room to the layer in contact with the back of the massive wall, where it is heated, and then back to the room. The solar energy is transferred to the building by conduction through the massive wall, and then by convection using a thermosyphon phenomenon. The monitoring of 2 solar houses in Verdun-Thierville (Meuse, France) has clearly shown, control issues of the air layer. The wall must be operated as autonomously as possible, to not be a constraint for the occupants and to get an optimization of the energy gains. To solve these problems, a composite solar wall prototype was erected in a test cell at Cadarache and tested in real operating conditions. This allows to use a more complete instrumentation, to have access more easily to the sensors and to study various configurations. The first experiments revealed an inverse thermosyphon phenomenon. To avoid this effect, two systems were designed, tested at Cadarache and then implemented in the walls at Verdun. (author) 77 refs.

  17. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

    International Nuclear Information System (INIS)

    Li Xinchun; Chen Zuanguang; Zhong Yuwen; Yang Fan; Pan Jianbin; Liang Yajing

    2012-01-01

    Highlights: ► CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. ► Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. ► An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. ► Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 μM (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and high sensitivity, hold great potential for hydrazine compounds assay in the lab-on-a-chip system.

  18. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

    Energy Technology Data Exchange (ETDEWEB)

    Li Xinchun [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Chen Zuanguang, E-mail: chenzg@mail.sysu.edu.cn [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Zhong Yuwen, E-mail: yu0106@163.com [Center for Disease Control and Prevention of Guangdong Province, 176 Xingangxi, Guangzhou 510300 (China); Yang Fan; Pan Jianbin; Liang Yajing [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. Black-Right-Pointing-Pointer Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. Black-Right-Pointing-Pointer An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. Black-Right-Pointing-Pointer Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 {mu}M (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and

  19. Tabique walls composite earth-based material characterization in the Alto Douro wine region, Portugal

    Directory of Open Access Journals (Sweden)

    Rui CARDOSO

    2015-12-01

    Full Text Available The Alto Douro Wine Region, located in the northeast of Portugal, a UNESCO World Heritage Site, presents a relevant tabique building stock, a traditional vernacular building technology. A technology based on a timber framed structure filled with a composite earth-based material. Meanwhile, previous research works have revealed that, principally in rural areas, this Portuguese heritage is highly deteriorated and damaged because of the rareness of conservation and strengthening works, which is partly related to the non-engineered character of this technology and to the growing phenomenon of rural to urban migration. Those aspects associated with the lack of scientific studies related to this technology motivated the writing of this paper, whose main purpose is the physical and chemical characterization of the earth-based material applied in the tabique buildings of that region. Consequently, an experimental work was conducted and the results obtained allowed, among others, the proposal of a particle size distribution envelope in respect to this material. This information will provide the means to assess the suitability of a given earth-based material in regard to this technology. The knowledge from this study could be very useful for the development of future normative documents and as a reference for architects and engineers that work with earth to guide and regulate future conservation, rehabilitation or construction processes helping to preserve this fabulous legacy.

  20. The Magma Chamber Simulator: Modeling the Impact of Wall Rock Composition on Mafic Magmas during Assimilation-Fractional Crystallization

    Science.gov (United States)

    Creamer, J. B.; Spera, F. J.; Bohrson, W. A.; Ghiorso, M. S.

    2012-12-01

    Although stoichiometric titration is often used to model the process of concurrent Assimilation and Fractional Crystallization (AFC) within a compositionally evolving magma body, a more complete treatment of the problem involves simultaneous and self-consistent determination of stable phase relationships and separately evolving temperatures of both Magma (M) and Wall Rock (WR) that interact as a composite M-WR system. Here we present results of M-WR systems undergoing AFC forward modeled with the Magma Chamber Simulator (MCS), which uses the phase modeling capabilities of MELTS (Ghiorso & Sack 1995) as the thermodynamic basis. Simulations begin with one of a variety of mafic magmas (e.g. HAB, MORB, AOB) intruding a set mass of Wall Rock (e.g. lherzolite, gabbro, diorite, granite, metapelite), and heat is exchanged as the M-WR system proceeds towards thermal equilibrium. Depending on initial conditions, the early part of the evolution can involve closed system FC while the WR heats up. The WR behaves as a closed system until it is heated beyond the solidus to critical limit for melt fraction extraction (fc), ranging between 0.08 and 0.12 depending on WR characteristics including composition and, rheology and stress field. Once fc is exceeded, a portion of the anatectic liquid is assimilated into the Magma. The MCS simultaneously calculates mass and composition of the mineral assemblage (Magma cumulates and WR residue) and melt (anatectic and Magma) at each T along the equilibration trajectory. Sensible and latent heat lost or gained plus mass gained by the Magma are accounted for by the MCS via governing Energy Constrained- Recharge Assimilation Fractional Crystallization (EC-RAFC) equations. In a comparison of two representative MCS results, consider a granitic WR intruded by HAB melt (51 wt. % SiO2) at liquidus T in shallow crust (0.1 GPa) with a WR/M ratio of 1.25, fc of 0.1 and a QFM oxygen buffer. In the first example, the WR begins at a temperature of 100o

  1. Electrospinning of Xanthan Polysaccharide

    DEFF Research Database (Denmark)

    Shekarforoush, Elhamalsadat; Faralli, Adele; Ndoni, Sokol

    2017-01-01

    .5 to 2.5 wt/vol%). The correlation between the concentration and the rheological properties of xanthan solutions, with the morphology of the nanofibers is investigated. At the polysaccharide concentrations where nanofiber formation is observed, an increase of the elastic modulus and first normal stress...... differences is observed. The typical “weak gel-like” and thixotropic properties known for aqueous xanthan solutions, are not observed for the xanthan solutions in formic acid. The Fourier transform infrared spectroscopic and circular dichroism studies verify that an esterification reaction takes place, where...

  2. Marine Derived Polysaccharides for Biomedical Applications: Chemical Modification Approaches

    Directory of Open Access Journals (Sweden)

    Paola Laurienzo

    2008-09-01

    Full Text Available Polysaccharide-based biomaterials are an emerging class in several biomedical fields such as tissue regeneration, particularly for cartilage, drug delivery devices and gelentrapment systems for the immobilization of cells. Important properties of the polysaccharides include controllable biological activity, biodegradability, and their ability to form hydrogels. Most of the polysaccharides used derive from natural sources; particularly, alginate and chitin, two polysaccharides which have an extensive history of use in medicine, pharmacy and basic sciences, and can be easily extracted from marine plants (algae kelp and crab shells, respectively. The recent rediscovery of poly-saccharidebased materials is also attributable to new synthetic routes for their chemical modification, with the aim of promoting new biological activities and/or to modify the final properties of the biomaterials for specific purposes. These synthetic strategies also involve the combination of polysaccharides with other polymers. A review of the more recent research in the field of chemical modification of alginate, chitin and its derivative chitosan is presented. Moreover, we report as case studies the results of our recent work concerning various different approaches and applications of polysaccharide-based biomaterials, such as the realization of novel composites based on calcium sulphate blended with alginate and with a chemically modified chitosan, the synthesis of novel alginate-poly(ethylene glycol copolymers and the development of a family of materials based on alginate and acrylic polymers of potential interest as drug delivery systems.

  3. [Analysis of thickening polysaccharides by the improved diethyldithioacetal derivatization method].

    Science.gov (United States)

    Akiyama, Takumi; Yamazaki, Takeshi; Tanamoto, Kenichi

    2011-01-01

    The identification test for thickening polysaccharides containing neutral saccharides and uronic acids was investigated by GC analysis of constituent monosaccharides. The reported method, in which monosaccharides were converted to diethyldithioacetal derivatives with ethanethiol followed by trimethylsilylation, was improved in terms of operability and reproducibility of GC/MS analysis. The suitability of the improved diethyldithioacetal derivatization method was determined for seven thickening polysaccharides, i.e., carob bean gum, guar gum, karaya gum, gum arabic, gum ghatti, tragacanth gum and peach gum. The samples were acid-hydrolyzed to form monosaccharides. The hydrolysates were derivatized and analyzed with GC/FID. Each sugar derivative was detected as a single peak and was well separated from others on the chromatograms. The amounts of constituent monosaccharides in thickening polysaccharides were successfully estimated. Seven polysaccharides were distinguished from each other on the basis of constituent monosaccharides. Further examination of the time period of hydrolysis of polysaccharides using peach gum showed that the optimal times were not the same for all monosaccharides. A longer time was needed to hydrolyze glucuronic acid than neutral saccharides. The findings suggest that hydrolysis time may sometimes affect the analytical results on composition of constituent monosaccharides in polysaccharides.

  4. [Comparison on polysaccharide content and PMP-HPLC fingerprints of polysaccharide in stems and leaves of Dendrobium officinale].

    Science.gov (United States)

    Zhou, Gui-Fen; Pang, Min-Xia; Chen, Su-Hong; Lv, Gui-Yuan; Yan, Mei-Qiu

    2014-03-01

    In order to provide scientific basics for exploitation and sufficient application of Dendrobium officinale leaves resources, the phenol-sulfuric acid method was applied to determine the polysaccharide content. The monosaccharides were derivated by PMP and the derivatives were identified by HPLC-DAD-ESI-MS(n) and the contents of mannose and glucose were determined simultaneously. Similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine (2004A) was employed to generate the mean chromatogram and similarity analysis of the samples was carried out. The results demonstrated that polysaccharide content, monosaccharide compositions and composition ratio had an obvious difference between stems and leaves. The polysaccharide content of stems was higher than that of leaves. Monosaccharide composition in leaf was significantly different from that in stem. The polysaccharide from stems was composed of mannose and glucose, however the polysaccharide of leaves was acid heteropolysaccharide and was mainly composed of five monosaccharides, including mannose, galacturonic acid, glucose, galactose and arabinose. The similarity value of the 14 batches was above 0.9, indicating that similarity of fingerprints among different samples was high. The study can provide evidence for expanding the medicinal parts of D. officinale.

  5. Polysaccharides on microsporocytes and tapetum in Rhoeo discolor. Cytochemical and autoradiographic study (/sup 3/H-glucose)

    Energy Technology Data Exchange (ETDEWEB)

    Albertini, L; Souvre, A [Ecole Nationale Superieure Agronomique, 31 - Toulouse (France); Toulouse-3 Univ., 31 (France))

    1978-01-01

    In Rhoeo discolor, we have been studying the evolution of cytoplasmic and wall polysaccharides on microsporocytes and tapetum by cytochemical and autoradiographic (6-/sup 3/H glucose) methods with particular attention to the meiocyte special wall, microspore intine, pollen generative cell wall, microsporocyte plastids and tapetum cytoplasm.

  6. Mechanical characterization and validation of poly (methyl methacrylate)/multi walled carbon nanotube composite for the polycentric knee joint.

    Science.gov (United States)

    Arun, S; Kanagaraj, S

    2015-10-01

    Trans femoral amputation is one of the most uncomfortable surgeries in patient׳s life, where the prosthesis consisting of a socket, knee joint, pylon and foot is used to do the walking activities. The artificial prosthetic knee joint imitates the functions of human knee to achieve the flexion-extension for the above knee amputee. The objective of present work is to develop a light weight composite material for the knee joint to reduce the metabolic cost of an amputee. Hence, an attempt was made to study the mechanical properties of multi walled carbon nanotubes (MWCNT) reinforced Poly (methyl methacrylate) (PMMA) prepared through melt mixing technique and optimize the concentration of reinforcement. The PMMA nanocomposites were prepared by reinforcing 0, 0.1, 0.2, 0.25, 0.3 and 0.4 wt% of MWCNT using injection moulding machine via twin screw extruder. It is observed that the tensile and flexural strength of PMMA, which were studied as per ASTM D638 and D790, respectively, were increased by 32.9% and 26.3% till 0.25 wt% reinforcement of MWCNT. The experimental results of strength and modulus were compared with theoretical prediction, where a good correlation was noted. It is concluded that the mechanical properties of PMMA were found to be increased to maximum at 0.25 wt% reinforcement of MWCNT, where the Pukanszky model and modified Halpin-Tsai model are suggested to predict the strength and modulus, respectively, of the PMMA/MWCNT composite, which can be opted as a suitable materiel for the development of polycentric knee joint. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Characterization of mechanical properties of hydroxyapatite-silicon-multi walled carbon nano tubes composite coatings synthesized by EPD on NiTi alloys for biomedical application.

    Science.gov (United States)

    Khalili, Vida; Khalil-Allafi, Jafar; Sengstock, Christina; Motemani, Yahya; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther; Köller, Manfred

    2016-06-01

    Release of Ni(1+) ions from NiTi alloy into tissue environment, biological response on the surface of NiTi and the allergic reaction of atopic people towards Ni are challengeable issues for biomedical application. In this study, composite coatings of hydroxyapatite-silicon multi walled carbon nano-tubes with 20wt% Silicon and 1wt% multi walled carbon nano-tubes of HA were deposited on a NiTi substrate using electrophoretic methods. The SEM images of coated samples exhibit a continuous and compact morphology for hydroxyapatite-silicon and hydroxyapatite-silicon-multi walled carbon nano-tubes coatings. Nano-indentation analysis on different locations of coatings represents the highest elastic modulus (45.8GPa) for HA-Si-MWCNTs which is between the elastic modulus of NiTi substrate (66.5GPa) and bone tissue (≈30GPa). This results in decrease of stress gradient on coating-substrate-bone interfaces during performance. The results of nano-scratch analysis show the highest critical distance of delamination (2.5mm) and normal load before failure (837mN) as well as highest critical contact pressure for hydroxyapatite-silicon-multi walled carbon nano-tubes coating. The cell culture results show that human mesenchymal stem cells are able to adhere and proliferate on the pure hydroxyapatite and composite coatings. The presence of both silicon and multi walled carbon nano-tubes (CS3) in the hydroxyapatite coating induce more adherence of viable human mesenchymal stem cells in contrast to the HA coated samples with only silicon (CS2). These results make hydroxyapatite-silicon-multi walled carbon nano-tubes a promising composite coating for future bone implant application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials

    Science.gov (United States)

    Irshidat, Mohammad

    A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

  9. Why Were Polysaccharides Necessary?

    Science.gov (United States)

    Tolstoguzov, Vladimir

    2004-12-01

    The main idea of this paper is that the primordial soup may be modelled by food systems whose structure-property relationship is based on non-specific interactions between denatured biopolymers. According to the proposed hypothesis, polysaccharides were the first biopolymers that decreased concentration of salts in the primordial soup, `compatibilised' and drove the joint evolution of proto-biopolymers. Synthesis of macromolecules within the polysaccharide-rich medium could have resulted in phase separation of the primordial soup and concentration of the polypeptides and nucleic acids in the dispersed phase particles. The concentration of proto-biopolymer mixtures favoured their cross-linking in hybrid supermacromolecules of conjugates. The cross-linking of proto-biopolymers could occur by hydrophobic, electrostatic interactions, H-bonds due to freezing aqueous mixed biopolymer dispersions and/or by covalent bonds due to the Maillard reaction. Cross-linking could have increased the local concentration of chemically different proto-biopolymers, fixed their relative positions and made their interactions reproducible. Attractive-repulsive interactions between cross-linked proto-biopolymer chains could develop pairing of the monomer units, improved chemical stability (against hydrolysis) and led to their mutual catalytic activity and coding. Conjugates could probably evolve to the first self-reproduced entities and then to specialized cellular organelles. Phase separation of the primordial soup with concentration of conjugates in the dispersed particles has probably resulted in proto-cells.

  10. Analysis of interlaminar fracture toughness and damage mechanisms in composite laminates reinforced with sprayed multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Almuhammadi, Khaled; Alfano, Marco; Yang, Yang; Lubineau, Gilles

    2014-01-01

    Highlights: • CNTs are solvent sprayed on CFRP prepreg to improve interlaminar fracture toughness. • Raman mapping revealed the actual penetration of CNTs across the interface. • A finite thickness nanoreinforced region was able to spread damage through CNT pull-out and peeling. • The induced dissipation mechanisms are operative at the microscale. • The nanoreinforcement strategy led to an increased fracture toughness. - Abstract: The present work is focused on the nanoreinforcement of prepreg based carbon fiber composite laminates to improve delamination resistance. Functionalized multi-walled carbon nanotubes (MWCNTs) were dispersed over the interface between prepreg layers through solvent spraying and the resulting mode I interlaminar fracture toughness was determined. For comparison, baseline samples with neat prepregs were also prepared. Results indicate that the introduction of functionalized MWCNTs can favorably affect the interlaminar fracture toughness, and the associated mechanisms of failure have been investigated. The manufacturing procedures and the interfacial reinforcing mechanism were explored by analyzing (i) the wettability between CNTs-solvent solution and prepreg surface, (ii) CNTs dispersion and (iii) the fractured surfaces through high resolution scanning electron microscopy and Raman mapping

  11. Facile preparation of disposable immunosensor for Shigella flexneri based on multi-wall carbon nanotubes/chitosan composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Guangying, E-mail: zhaogy-user@163.co [Food Safety Key Lab of Zhejiang Province, Department of Food Quality and Safety, Zhejiang Gongshang University, 149, Jiaogong Road, Hangzhou 310035, Zhejiang Province (China); Zhan Xuejia [Food Safety Key Lab of Zhejiang Province, Department of Food Quality and Safety, Zhejiang Gongshang University, 149, Jiaogong Road, Hangzhou 310035, Zhejiang Province (China)

    2010-02-28

    Based on multi-wall carbon nanotubes (MWCNT)/chitosan/horseradish peroxidase labeled antibodies to Shigella flexneri (HRP-anti-S. flexneri) biocomposite film on a screen-printed electrode (SPE) surface, a disposable immunosensor has been developed for the rapid detection of S. flexneri. The HRP-anti-S. flexneri can be entrapped into MWCNT/chitosan composite matrix without other cross-linking agent. Thionine and H{sub 2}O{sub 2} were used as the mediator and substrate, respectively. The surface morphologies of modified films were characterized by atomic force microscope (AFM). Cyclic voltammery (CV) was carried out to characterize the electrochemical properties of the immobilization of materials on the electrode surface and quantified S. flexneri. Due to the strong electrocatalytic properties of MWCNT and HRP toward H{sub 2}O{sub 2}, the response signal was significantly amplified. S. flexneri could be detected by the decrease of the reduction peak current before and after immunoreaction. Under optimal conditions, S. flexneri could be detected in the range of 10{sup 4} to 10{sup 10} cfu mL{sup -1}, with a detection limit of 2.3 x 10{sup 3} cfu mL{sup -1} (S/N = 3). Furthermore, the proposed immunosensor exhibited a satisfactory specificity, reproducibility, stability and accuracy, indicating that the proposed immunosensor has potential application for a facile, rapid and harmless immunoassay.

  12. Facile preparation of disposable immunosensor for Shigella flexneri based on multi-wall carbon nanotubes/chitosan composite

    International Nuclear Information System (INIS)

    Zhao Guangying; Zhan Xuejia

    2010-01-01

    Based on multi-wall carbon nanotubes (MWCNT)/chitosan/horseradish peroxidase labeled antibodies to Shigella flexneri (HRP-anti-S. flexneri) biocomposite film on a screen-printed electrode (SPE) surface, a disposable immunosensor has been developed for the rapid detection of S. flexneri. The HRP-anti-S. flexneri can be entrapped into MWCNT/chitosan composite matrix without other cross-linking agent. Thionine and H 2 O 2 were used as the mediator and substrate, respectively. The surface morphologies of modified films were characterized by atomic force microscope (AFM). Cyclic voltammery (CV) was carried out to characterize the electrochemical properties of the immobilization of materials on the electrode surface and quantified S. flexneri. Due to the strong electrocatalytic properties of MWCNT and HRP toward H 2 O 2 , the response signal was significantly amplified. S. flexneri could be detected by the decrease of the reduction peak current before and after immunoreaction. Under optimal conditions, S. flexneri could be detected in the range of 10 4 to 10 10 cfu mL -1 , with a detection limit of 2.3 x 10 3 cfu mL -1 (S/N = 3). Furthermore, the proposed immunosensor exhibited a satisfactory specificity, reproducibility, stability and accuracy, indicating that the proposed immunosensor has potential application for a facile, rapid and harmless immunoassay.

  13. Surface-Anchored Poly(4-vinylpyridine)–Single-Walled Carbon Nanotube–Metal Composites for Gas Detection

    KAUST Repository

    Yoon, Bora

    2016-08-05

    A platform for chemiresistive gas detectors based upon single-walled carbon nanotube (SWCNT) dispersions stabilized by poly(4-vinylpyridine) (P4VP) covalently immobilized onto a glass substrate was developed. To fabricate these devices, a glass substrate with gold electrodes is treated with 3-bromopropyltrichlorosilane. The resulting alkyl bromide coating presents groups that can react with the P4VP to covalently bond (anchor) the polymer–SWCNT composite to the substrate. Residual pyridyl groups in P4VP not consumed in this quaternization reaction are available to coordinate metal nanoparticles or ions chosen to confer selectivity and sensitivity to target gas analytes. Generation of P4VP coordinated to silver nanoparticles produces an enhanced response to ammonia gas. The incorporation of soft Lewis acidic Pd2+ cations by binding PdCl2 to P4VP yields a selective and highly sensitive device that changes resistance upon exposure to vapors of thioethers. The latter materials have utility for odorized fuel leak detection, microbial activity, and breath diagnostics. A third demonstration makes use of permanganate incorporation to produce devices with large responses to vapors of volatile organic compounds that are susceptible to oxidation.

  14. Field emission from a composite structure consisting of vertically aligned single-walled carbon nanotubes and carbon nanocones

    International Nuclear Information System (INIS)

    Yeh, C M; Chen, M Y; Hwang, J; Gan, J-Y; Kou, C S

    2006-01-01

    Vertically aligned single-walled carbon nanotubes (VA-SWCNTs) have been fabricated on carbon nanocones (CNCs) in a gravity-assisted chemical vapour deposition (CVD) process. The CNCs with nanoscale Co particles at the top were first grown on the Co/Si(100) substrate biased at 350 V in a plasma enhanced chemical vapour deposition process. The CNCs typically are ∼200 nm in height, and their diameters are ∼100 nm near the bottom and ∼10 nm at the top. The nanoscale Co particles ∼10 nm in diameter act as catalysts which favour the growth of VA-SWCNTs out of CNCs at 850 0 C in the gravity-assisted CVD process. The average length and the growth time of VA-SWCNTs are ∼150 nm and 1.5 min, equivalent to a growth rate of ∼6 μm h -1 . The diameters of VA-SWCNTs are estimated to be 1.2-2.1 nm. When VA-SWCNTs are fabricated on CNCs, the turn-on voltage is reduced from 3.9 to 0.7 V μm -1 and the emission current density at the electric field of 5 V μm -1 is enhanced by a factor of more than 200. The composite VA-SWCNT/CNC structure is potentially an excellent field emitter. The emission stability of the VA-SWCNT/CNC field emitter is discussed

  15. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

    Directory of Open Access Journals (Sweden)

    Hoon-Sang Chang

    2013-07-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. MATERIAL AND METHODS: Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. RESULTS: The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. CONCLUSION: In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

  16. A 3-D Model of a Perennial Ryegrass Primary Cell Wall and Its Enzymatic Degradation

    Directory of Open Access Journals (Sweden)

    Indrakumar Vetharaniam

    2014-05-01

    Full Text Available We have developed a novel 3-D, agent-based model of cell-wall digestion to improve our understanding of ruminal cell-wall digestion. It offers a capability to study cell walls and their enzymatic modification, by providing a representation of cellulose microfibrils and non-cellulosic polysaccharides and by simulating their spatial and catalytic interactions with enzymes. One can vary cell-wall composition and the types and numbers of enzyme molecules, allowing the model to be applied to a range of systems where cell walls are degraded and to the modification of cell walls by endogenous enzymes. As a proof of principle, we have modelled the wall of a mesophyll cell from the leaf of perennial ryegrass and then simulated its enzymatic degradation. This is a primary, non-lignified cell wall and the model includes cellulose, hemicelluloses (glucuronoarabinoxylans, 1,3;1,4-β-glucans, and xyloglucans and pectin. These polymers are represented at the level of constituent monosaccharides, and assembled to form a 3-D, meso-scale representation of the molecular structure of the cell wall. The composition of the cell wall can be parameterised to represent different walls in different cell types and taxa. The model can contain arbitrary combinations of different enzymes. It simulates their random diffusion through the polymer networks taking collisions into account, allowing steric hindrance from cell-wall polymers to be modelled. Steric considerations are included when target bonds are encountered, and breakdown products resulting from enzymatic activity are predicted.

  17. Brittle stalk 2 encodes a putative glycosylphosphatidylinositol-anchored protein that affects mechanical strength of maize tissues by altering the composition and structure of secondary cell walls.

    Science.gov (United States)

    Ching, Ada; Dhugga, Kanwarpal S; Appenzeller, Laura; Meeley, Robert; Bourett, Timothy M; Howard, Richard J; Rafalski, Antoni

    2006-10-01

    A spontaneous maize mutant, brittle stalk-2 (bk2-ref), exhibits dramatically reduced tissue mechanical strength. Reduction in mechanical strength in the stalk tissue was highly correlated with a reduction in the amount of cellulose and an uneven deposition of secondary cell wall material in the subepidermal and perivascular sclerenchyma fibers. Cell wall accounted for two-thirds of the observed reduction in dry matter content per unit length of the mutant stalk in comparison to the wildtype stalk. Although the cell wall composition was significantly altered in the mutant in comparison to the wildtype stalks, no compensation by lignin and cell wall matrix for reduced cellulose amount was observed. We demonstrate that Bk2 encodes a Cobra-like protein that is homologous to the rice Bc1 protein. In the bk2-ref gene, a 1 kb transposon-like element is inserted in the beginning of the second exon, disrupting the open reading frame. The Bk2 gene was expressed in the stalk, husk, root, and leaf tissues, but not in the embryo, endosperm, pollen, silk, or other tissues with comparatively few or no secondary cell wall containing cells. The highest expression was in the isolated vascular bundles. In agreement with its role in secondary wall formation, the expression pattern of the Bk2 gene was very similar to that of the ZmCesA10, ZmCesA11, and ZmCesA12 genes, which are known to be involved in secondary wall formation. We have isolated an independent Mutator-tagged allele of bk2, referred to as bk2-Mu7, the phenotype of which is similar to that of the spontaneous mutant. Our results demonstrate that mutations in the Bk2 gene affect stalk strength in maize by interfering with the deposition of cellulose in the secondary cell wall in fiber cells.

  18. Sulfated Polysaccharides in the Freshwater Green Macroalga Cladophora surera Not Linked to Salinity Adaptation.

    Science.gov (United States)

    Arata, Paula X; Alberghina, Josefina; Confalonieri, Viviana; Errea, María I; Estevez, José M; Ciancia, Marina

    2017-01-01

    The presence of sulfated polysaccharides in cell walls of seaweeds is considered to be a consequence of the physiological adaptation to the high salinity of the marine environment. Recently, it was found that sulfated polysaccharides were present in certain freshwater Cladophora species and some vascular plants. Cladophora (Ulvophyceae, Chlorophyta) is one of the largest genera of green algae that are able to grow in both, seas and freshwater courses. Previous studies carried out on the water-soluble polysaccharides of the marine species C. falklandica established the presence of sulfated xylogalactoarabinans constituted by a backbone of 4-linked β-L-arabinopyranose units partially sulfated mainly on C3 and also on C2 with partial glycosylation, mostly on C2, with terminal β-D-xylopyranose or β-D-galactofuranose units. Besides, minor amounts of 3-, 6- and/or 3,6-linked β-D-galactan structures, with galactose in the pyranosic form were detected. In this work, the main water soluble cell wall polysaccharides from the freshwater alga Cladophora surera were characterized. It was found that this green alga biosynthesizes sulfated polysaccharides, with a structure similar to those found in marine species of this genus. Calibration of molecular clock with fossil data suggests that colonization of freshwater environments occurred during the Miocene by its ancestor. Therefore, the presence of sulfated polysaccharides in the freshwater green macroalga C. surera could be, in this case, an adaptation to transient desiccation and changes in ionic strength. Retention of sulfated polysaccharides at the cell walls may represent a snapshot of an evolutionary event, and, thus constitutes an excellent model for further studies on the mechanisms of sulfation on cell wall polysaccharides and environmental stress co-evolution.

  19. Sulfated Polysaccharides in the Freshwater Green Macroalga Cladophora surera Not Linked to Salinity Adaptation

    Directory of Open Access Journals (Sweden)

    Paula X. Arata

    2017-11-01

    Full Text Available The presence of sulfated polysaccharides in cell walls of seaweeds is considered to be a consequence of the physiological adaptation to the high salinity of the marine environment. Recently, it was found that sulfated polysaccharides were present in certain freshwater Cladophora species and some vascular plants. Cladophora (Ulvophyceae, Chlorophyta is one of the largest genera of green algae that are able to grow in both, seas and freshwater courses. Previous studies carried out on the water-soluble polysaccharides of the marine species C. falklandica established the presence of sulfated xylogalactoarabinans constituted by a backbone of 4-linked β-L-arabinopyranose units partially sulfated mainly on C3 and also on C2 with partial glycosylation, mostly on C2, with terminal β-D-xylopyranose or β-D-galactofuranose units. Besides, minor amounts of 3-, 6- and/or 3,6-linked β-D-galactan structures, with galactose in the pyranosic form were detected. In this work, the main water soluble cell wall polysaccharides from the freshwater alga Cladophora surera were characterized. It was found that this green alga biosynthesizes sulfated polysaccharides, with a structure similar to those found in marine species of this genus. Calibration of molecular clock with fossil data suggests that colonization of freshwater environments occurred during the Miocene by its ancestor. Therefore, the presence of sulfated polysaccharides in the freshwater green macroalga C. surera could be, in this case, an adaptation to transient desiccation and changes in ionic strength. Retention of sulfated polysaccharides at the cell walls may represent a snapshot of an evolutionary event, and, thus constitutes an excellent model for further studies on the mechanisms of sulfation on cell wall polysaccharides and environmental stress co-evolution.

  20. Comparison of mechanical properties of multi-walled carbon nanotube and graphene nanosheet/polyethylene oxide composites plasticized with lithium triflate

    Science.gov (United States)

    Jurkane, A.; Gaidukov, S.

    2017-10-01

    A strong engineering interest in nanostructured conducting polymers and its composite materials have been widely used to build various sensor devices, electronic interconnect devices, fuel cells and batteries. Preparation of polymeric nano-composites with finely controlled structure, especially, at nano-scale, is still one of the most perspective modification ways of the properties of polymeric composites. Multi-walled carbon nanotube (MWCNT)/polyethylene oxide (PEO) and graphene nanosheets (GR)/PEO composites and composite of MWCNT/GR/PEO were prepared by solution casting and hot-pressing method. Composites were plasticized by 5% of Lithium triflate (LiTrifl), which play role of additional ion source in conducting polymer composite. Mechanical tensile tests were performed to evaluate nanoparticles influence on the mechanical strength of the conductive polymer composite materials. Difference of tensile tests of prepared composition can be seen from tensile tests data curves. The results of tensile tests indicated that the nanoparticles can provide PEO/5%LiTrifl composite with stiffening effects at rather low filler content (at least 0.05% by volume).

  1. Electrocatalytic behahiour of cobalt tetraamino-phthalocyanine in the presence of a composite of reduced graphene nanosheets and of multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Nyoni, Stephen; Nyokong, Tebello

    2014-01-01

    Graphical abstract: A composite of multi-walled carbon nanotubes, reduced graphene nanosheets and cobalt tetraamino phthalocyanine was used for electrode modification, resulting in a rough surface as judged by scanning electrochemical microscopy. - Highlights: • Conjugates of multi-walled carbon nanotubes and reduced graphene nanosheets were used to modify glassy carbon electrode. • The electrode was further modified with cobalt tetraamino phthalocyanine. • The modified electrode was employed for the detection of paraquat. • A mechanism for paraquat detection using the composite electrodes is proposed. - Abstract: A composite of multi-walled carbon nanotubes (MWCNT) with reduced graphene nanosheets (rGNS-2) was developed in order to minimize the restacking of the latter. The composite was used to modify a glassy carbon electrode (GCE). GCE was further modified with cobalt tetraamino phthalocyanine (CoTAPc). The modified electrode is represented as rGNS-2-MWCNT-CoTAPc-GCE. X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electrochemical microscopy and Raman spectroscopy were used to explore into surface functionalities, morphology and topography of the nanocomposite. The rGNS-2-MWCNT-CoTAPc-GCE had a low limit of detection of 3.32 × 10 −8 M towards the detection of paraguat as a test analyte. A mechanism for paraquat detection using an rGNS-2-MWCNT-CoTAPc-GCE is also proposed in this work

  2. Antioxidant and immunomodulatory properties of polysaccharides from Allanblackia floribunda Oliv stem bark and Chromolaena odorata (L.) King and H.E. Robins leaves.

    Science.gov (United States)

    Boudjeko, Thaddée; Megnekou, Rosette; Woguia, Alice Louise; Kegne, Francine Mediesse; Ngomoyogoli, Judith Emery Kanemoto; Tchapoum, Christiane Danielle Nounga; Koum, Olga

    2015-12-09

    Many plant polysaccharides have shown high antioxidant and immunostimulating properties and can be explored as novel molecules with biological properties that can potentially improve immune function. The objective of this work was to characterize soluble and cell wall polysaccharides isolated from the stem bark of Allanblackia floribunda and Chromolaena odorata leaves and to evaluate their antioxidant and immunomodulatory properties. Three polysaccharide fractions: soluble polysaccharides (PoS), pectins (Pec) and hemicelluloses (Hem) were extracted from A. floribunda stem bark and C. odorata leaves. These samples were analysed for their proteins, phenolic compounds and total sugar contents. The monosaccharide composition was determined by gas chromatography and arabinogalactan proteins content in PoS was evaluated by rocket electrophoresis. The in vitro antioxidant activities were evaluated by 1, 1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2'-azino-bis-3-éthylbenzylthiazoline-6-sulphonic acid (ABTS) radical scavenging assays and ferrous ions chelating activity. Immunomodulatory activities were performed on the peripheral blood mononuclear cells (PBMCs) using proliferation and enzyme linked immunospot (ELISPOT) method to determine the production of an interferon-gamma. The characterization of the various fractions showed varied metabolites in each plant. In PoS fractions, Ara and Gal were the major monosaccharides found, indicating that arabinogalactans are the primary macromolecules. Hem fractions contained predominantly Xyl and GalA for A. floribunda and Xyl (upto 80 %) for and C. odorata. A. floribunda Hem fraction and C. odorata PoS fraction showed significant DPPH and ABTS radical scavenging activities and immunostimulatory activity via stimulation of PBMC and production of IFN-γ in a dose-dependent manner. The results obtained from this study support the ethnomedicinal use of the stem bark of A. floribunda and leaves of C. odorata. Further research is

  3. Structural Studies of Complex Carbohydrates of Plant Cell Walls

    Energy Technology Data Exchange (ETDEWEB)

    Darvill, Alan [Univ. of Georgia, Athens, GA (United States); Hahn, Michael G. [Univ. of Georgia, Athens, GA (United States); O' Neill, Malcolm A. [Univ. of Georgia, Athens, GA (United States); York, William S. [Univ. of Georgia, Athens, GA (United States)

    2015-02-17

    Most of the solar energy captured by land plants is converted into the polysaccharides (cellulose, hemicellulose, and pectin) that are the predominant components of the cell wall. These walls, which account for the bulk of plant biomass, have numerous roles in the growth and development of plants. Moreover, these walls have a major impact on human life as they are a renewable source of biomass, a source of diverse commercially useful polymers, a major component of wood, and a source of nutrition for humans and livestock. Thus, understanding the molecular mechanisms that lead to wall assembly and how cell walls and their component polysaccharides contribute to plant growth and development is essential to improve and extend the productivity and value of plant materials. The proposed research will develop and apply advanced analytical and immunological techniques to study specific changes in the structures and interactions of the hemicellulosic and pectic polysaccharides that occur during differentiation and in response to genetic modification and chemical treatments that affect wall biosynthesis. These new techniques will make it possible to accurately characterize minute amounts of cell wall polysaccharides so that subtle changes in structure that occur in individual cell types can be identified and correlated to the physiological or developmental state of the plant. Successful implementation of this research will reveal fundamental relationships between polysaccharide structure, cell wall architecture, and cell wall functions.

  4. Salt Effect on the Antioxidant Activity of Red Microalgal Sulfated Polysaccharides in Soy-Bean Formula.

    Science.gov (United States)

    Burg, Ariela; Oshrat, Levy-Ontman

    2015-10-20

    Sulfated polysaccharides produced by microalgae, which are known to exhibit various biological activities, may potentially serve as natural antioxidant sources. To date, only a few studies have examined the antioxidant bioactivity of red microalgal polysaccharides. In this research, the effect of different salts on the antioxidant activities of two red microalgal sulfated polysaccharides derived from Porphyridium sp. and Porphyridium aerugineum were studied in a soy bean-based infant milk formula. Salt composition and concentration were both shown to affect the polysaccharides' antioxidant activity. It can be postulated that the salt ions intefer with the polysaccharide chains' interactions and alter their structure, leading to a new three-dimensional structure that better exposes antiooxidant sites in comparison to the polysaccharide without salt supplement. Among the cations that were studied, Ca(2+) had the strongest enhancement effect on antioxidant activities of both polysaccharides. Understanding the effect of salts on polysaccharides' stucture, in addition to furthering knowledge on polysaccharide bioactivities, may also shed light on the position of the antioxidant active sites.

  5. Microstructure and mechanical properties of in situ casting TiC/Ti6Al4V composites through adding multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ya, Bin; Zhou, Bingwen; Yang, Hongshuo; Huang, Bingkun; Jia, Fei; Zhang, Xingguo, E-mail: zxgwj@dlut.edu.cn

    2015-07-15

    Highlights: • Adding MWCNTs in situ casting fabricating TiC/Ti6Al4V composites is first reported. • The solidification process of in situ casting TiC/Ti6Al4V composites is discussed. • Microstructure shows remarkable correlations with adding MWCNTS. • Strength and plasticity show remarkable correlations with adding MWCNTs. - Abstract: In this study, multi-walled carbon nanotubes (MWCNTs) were added as carbon sources to fabricate in situ casting TiC/Ti6Al4V (TC4) composites. The effects of MWCNTs on the microstructure and mechanical properties are studied. The composites are analyzed by X-ray diffraction, field-emission scanning electron microscope and electron probe microanalysis. The fracture behavior of TiC/TC4 composites are also studied. Smaller size of TiC particles and grain compared with TC4-graphite composites can be observed. The tensile strength of TC4-MWCNTs composites is about 1110.1 MPa, which is higher than that of TC4-graphite composites, about 1003.6 MPa. Fracture behavior also was changed by adding MWCNTs in situ casting TiC/TC4 composites.

  6. Altered cell wall disassembly during ripening of Cnr tomato fruit: implications for cell adhesion and fruit softening

    DEFF Research Database (Denmark)

    Orfila, C.; Huisman, M.M.H.; Willats, William George Tycho

    2002-01-01

    The Cnr (Colourless non-ripening) tomato (Lycopersicon esculentum Mill.) mutant has an aberrant fruit-ripening phenotype in which fruit do not soften and have reduced cell adhesion between pericarp cells. Cell walls from Cnr fruit were analysed in order to assess the possible contribution of pectic...... polysaccharides to the non-softening and altered cell adhesion phenotype. Cell wall material (CWM) and solubilised fractions of mature green and red ripe fruit were analysed by chemical, enzymatic and immunochemical techniques. No major differences in CWM sugar composition were detected although differences were...... that was chelator-soluble was 50% less in Cnr cell walls at both the mature green and red ripe stages. Chelator-soluble material from ripe-stage Cnr was more susceptible to endo-polygalacturonase degradation than the corresponding material from wild-type fruit. In addition, cell walls from Cnr fruit contained...

  7. [Cellular composition of lymphoid nodules in the trachea wall in rats with different resistance to emotional stress in a model of hemorrhagic stroke].

    Science.gov (United States)

    Klyueva, L A

    2017-01-01

    To reveal regularities of changes in cellular composition of lymphoid nodules in the tracheal wall in male Wistar rats resistant and not resistant to emotional stress in a model of hemorrhagic stroke. Lymphoid formations of the tracheal wall (an area near the bifurcation of the organ) were investigated in 98 male Wistar rats using histological methods. Significant changes in the cellular composition of lymphoid nodules were found. The pattern of changes depends on the stress resistance of rats and the period of the experiment. The active cell destruction in lymphoid nodules was noted both in stress resistant and stress susceptible animals. The changes in the structure of lymphoid nodules found in the experimental hemorrhagic stroke suggest a decrease in the local immune resistance, which is most pronounced in rats not resistant to stress, that may contribute to the development of severe inflammatory complications of stroke such as pneumonia.

  8. An Applied Method for Predicting the Load-Carrying Capacity in Compression of Thin-Wall Composite Structures with Impact Damage

    Science.gov (United States)

    Mitrofanov, O.; Pavelko, I.; Varickis, S.; Vagele, A.

    2018-03-01

    The necessity for considering both strength criteria and postbuckling effects in calculating the load-carrying capacity in compression of thin-wall composite structures with impact damage is substantiated. An original applied method ensuring solution of these problems with an accuracy sufficient for practical design tasks is developed. The main advantage of the method is its applicability in terms of computing resources and the set of initial data required. The results of application of the method to solution of the problem of compression of fragments of thin-wall honeycomb panel damaged by impacts of various energies are presented. After a comparison of calculation results with experimental data, a working algorithm for calculating the reduction in the load-carrying capacity of a composite object with impact damage is adopted.

  9. Composite of TiN nanoparticles and few-walled carbon nanotubes and its application to the electrocatalytic oxygen reduction reaction

    KAUST Repository

    Isogai, Shunsuke

    2011-11-30

    Nanoparticles meet nanotubes! Direct synthesis of TiN nanoparticles in a three-dimensional network of few-walled carbon nanotubes (FWCNTs) was achieved by using mesoporous graphitic carbon nitride (C 3N 4) as both a hard template and a nitrogen source. The TiN/FWCNT composite showed high performance for the oxygen reduction reaction in acidic media. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Attachment of Salmonella strains to a plant cell wall model is modulated by surface characteristics and not by specific carbohydrate interactions.

    Science.gov (United States)

    Tan, Michelle Sze-Fan; Moore, Sean C; Tabor, Rico F; Fegan, Narelle; Rahman, Sadequr; Dykes, Gary A

    2016-09-15

    Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface. We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin. Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by

  11. Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan-silica nanoparticles strongly depends on the metabolic activity type of the cell line

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Zwe-Ling, E-mail: kongzl@mail.ntou.edu.tw; Chang, Jenq-Sheng; Chang, Ke Liang B. [National Taiwan Ocean University, Department of Food Science (China)

    2013-09-15

    Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica-chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica-chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica-chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan-silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line.

  12. Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan-silica nanoparticles strongly depends on the metabolic activity type of the cell line

    Science.gov (United States)

    Kong, Zwe-Ling; Chang, Jenq-Sheng; Chang, Ke Liang B.

    2013-09-01

    Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica-chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica-chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica-chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan-silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line.

  13. Antiproliferative effect of Antrodia camphorata polysaccharides encapsulated in chitosan–silica nanoparticles strongly depends on the metabolic activity type of the cell line

    International Nuclear Information System (INIS)

    Kong, Zwe-Ling; Chang, Jenq-Sheng; Chang, Ke Liang B.

    2013-01-01

    Chitosan molecules interact with silica and encapsulate the Antrodia camphorata extract (ACE) polysaccharides to form composite nanoparticles. The nanoparticle suspensions of ACE polysaccharides encapsulated in silica–chitosan and silica nanoparticles approach an average particle size of 210 and 294 nm in solution, respectively. The encapsulation efficiencies of ACE polysaccharides are 66 and 63.5 %, respectively. Scanning electron micrographs confirm the formation of near-spherical nanoparticles. ACE polysaccharides solution had better antioxidative capability than ACE polysaccharides encapsulated in silica or silica–chitosan nanoparticles suspensions. The antioxidant capacity of nanoparticles increases with increasing dissolution time. The antitumor effects of ACE polysaccharides, ACE polysaccharides encapsulated in silica, or silica–chitosan nanoparticles increased with increasing concentration of nanoparticles. This is the first report demonstrating the potential of ACE polysaccharides encapsulated in chitosan–silica nanoparticles for cancer chemoprevention. Furthermore, this study suggests that antiproliferative effect of nanoparticle-encapsulated bioactive could significantly depend on the metabolic activity type of the cell line

  14. Structural studies of the O-specific polysaccharide(s) from the lipopolysaccharide of Azospirillum brasilense type strain Sp7.

    Science.gov (United States)

    Sigida, Elena N; Fedonenko, Yuliya P; Shashkov, Alexander S; Zdorovenko, Evelina L; Konnova, Svetlana A; Ignatov, Vladimir V; Knirel, Yuriy A

    2013-10-18

    Lipopolysaccharide was obtained by phenol-water extraction from dried bacterial cells of Azospirillum brasilense type strain Sp7. Mild acid hydrolysis of the lipopolysaccharide followed by GPC on Sephadex G-50 resulted in a polysaccharide mixture, which was studied by composition and methylation analyses, Smith degradation and (1)H and (13)C NMR spectroscopy. The following polysaccharide structures were established, where italics indicate a non-stoichiometric (∼40%) 2-O-methylation of l-rhamnose. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Crosslinked ionic polysaccharides for stimuli-sensitive drug delivery.

    Science.gov (United States)

    Alvarez-Lorenzo, Carmen; Blanco-Fernandez, Barbara; Puga, Ana M; Concheiro, Angel

    2013-08-01

    Polysaccharides are gaining increasing attention as components of stimuli-responsive drug delivery systems, particularly since they can be obtained in a well characterized and reproducible way from the natural sources. Ionic polysaccharides can be readily crosslinked to render hydrogel networks sensitive to a variety of internal and external variables, and thus suitable for switching drug release on-off through diverse mechanisms. Hybrids, composites and grafted polymers can reinforce the responsiveness and widen the range of stimuli to which polysaccharide-based systems can respond. This review analyzes the state of the art of crosslinked ionic polysaccharides as components of delivery systems that can regulate drug release as a function of changes in pH, ion nature and concentration, electric and magnetic field intensity, light wavelength, temperature, redox potential, and certain molecules (enzymes, illness markers, and so on). Examples of specific applications are provided. The information compiled demonstrates that crosslinked networks of ionic polysaccharides are suitable building blocks for developing advanced externally activated and feed-back modulated drug delivery systems. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Chemical studies on the polysaccharides of Salicornia brachiata.

    Science.gov (United States)

    Sanandiya, Naresh D; Siddhanta, A K

    2014-11-04

    A group of 12 polysaccharide extracts were prepared from the tips, stem and roots of an Indian halophyte Salicornia brachiata Roxb. obtained by sequential extractions with cold water (CW), hot water (HW), aqueous ammonium oxalate (OX) and aqueous sodium hydroxide (ALK) solutions. Monosaccharide composition analysis revealed that all the polysaccharide extract samples consisted primarily of rhamnose, arabinose, mannose, galactose, glucose, whereas ribose and xylose were present only in some of the extracts. All the extracts exhibited low apparent viscosity (1.47-2.02 cP) and sulphate and contained no prominent toxic metal ions. Fucose was detected only in OX extract of the roots. These polysaccharides were found to be heterogeneous and highly branched (glycoside linkage analysis, size-exclusion chromatography, (13)C-NMR, FT-IR, circular dichroism and optical rotation data). Physico-chemical analyses of these polysaccharides including uronic acid, sulphate and protein contents were also carried out. This constitutes the first report on the profiling of Salicornia polysaccharides. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Computer simulation and experimental study of the polysaccharide-polysaccharide interaction in the bacteria Azospirillum brasilense Sp245

    Science.gov (United States)

    Arefeva, Oksana A.; Kuznetsov, Pavel E.; Tolmachev, Sergey A.; Kupadze, Machammad S.; Khlebtsov, Boris N.; Rogacheva, Svetlana M.

    2003-09-01

    We have studied the conformational properties and molecular dynamics of polysaccharides by using molecular modeling methods. Theoretical and experimental results of polysaccharide-polysaccharide interactions are described.

  18. Investigation of Plant Cell Wall Properties: A Study of Contributions from the Nanoscale to the Macroscale Impacting Cell Wall Recalcitrance

    Science.gov (United States)

    Crowe, Jacob Dillon

    Biochemical conversion of lignocellulosic biomass to fuel ethanol is one of a few challenging, yet opportune technologies that can reduce the consumption of petroleum-derived transportation fuels, while providing parallel reductions in greenhouse gas emissions. Biomass recalcitrance, or resistance to deconstruction, is a major technical challenge that limits effective conversion of biomass to fermentable sugars, often requiring a costly thermochemical pretreatment step to improve biomass deconstruction. Biomass recalcitrance is imparted largely by the secondary cell wall, a complex polymeric matrix of cell wall polysaccharides and aromatic heteropolymers, that provides structural stability to cells and enables plant upright growth. Polymers within the cell wall can vary both compositionally and structurally depending upon plant species and anatomical fraction, and have varied responses to thermochemical pretreatments. Cell wall properties impacting recalcitrance are still not well understood, and as a result, the goal of this dissertation is to investigate structural features of the cell wall contributing to recalcitrance (1) in diverse anatomical fractions of a single species, (2) in response to diverse pretreatments, and (3) resulting from genetic modification. In the first study, feedstock cell wall heterogeneity was investigated in anatomical (stem, leaf sheaths, and leaf blades) and internode fractions of switchgrass at varying tissue maturities. Lignin content was observed as the key contributor to recalcitrance in maturing stem tissues only, with non-cellulosic substituted glucuronoarabinoxylans and pectic polysaccharides contributing to cell wall recalcitrance in leaf sheath and leaf blades. Hydroxycinnamate (i.e., saponifiable p-coumarate and ferulate) content along with xylan and pectin extractability decreased with tissue maturity, suggesting lignification is only one component imparting maturity specific cell wall recalcitrance. In the second study

  19. Development of an efficient Procedure for Resist Wall Space Experiment

    Science.gov (United States)

    Matsumoto, Shouhei; Kumasaki, Saori; Higuchi, Sayoko; Kirihata, Kuniaki; Inoue, Yasue; Fujie, Miho; Soga, Kouichi; Wakabayashi, Kazuyuki; Hoson, Takayuki

    The Resist Wall space experiment aims to examine the role of the cortical microtubule-plasma membrane-cell wall continuum in plant resistance to the gravitational force, thereby clarifying the mechanism of gravity resistance. For this purpose, we will cultivate Arabidopsis mutants defective in organization of cortical microtubules (tua6 ) or synthesis of membrane sterols (hmg1 ) as well as the wild type under microgravity and 1 g conditions in the European Modular Cultivation System on the International Space Station up to reproductive stage, and compare phenotypes on growth and development. We will also analyze cell wall properties and gene expression levels using collected materials. However, the amounts of materials collected will be severely limited, and we should develop an efficient procedure for this space experiment. In the present study, we examined the possibility of analyzing various parameters successively using the identical material. On orbit, plant materials will be fixed with RNAlater solution, kept at 4° C for several days and then frozen in a freezer at -20° C. We first examined whether the cell wall extensibility of inflorescence stems can be measured after RNAlater fixation. The gradient of the cell wall extensibility along inflorescence stems was detected in RNAlater-fixed materials as in methanol-killed ones. The sufficient amounts of RNA to analyze the gene expression were also obtained from the materials after measurement of the cell wall extensibility. Furthermore, the levels and composition of cell wall polysaccharides could be measured using the materials after extraction of RNA. These results show that we can analyze the physical and chemical properties of the cell wall as well as gene expression using the identical material obtained in the space experiments.

  20. Aspergillus nidulans cell wall composition and function change in response to hosting several Aspergillus fumigatus UDP-galactopyranose mutase activity mutants.

    Directory of Open Access Journals (Sweden)

    Md Kausar Alam

    Full Text Available Deletion or repression of Aspergillus nidulans ugmA (AnugmA, involved in galactofuranose biosynthesis, impairs growth and increases sensitivity to Caspofungin, a β-1,3-glucan synthesis antagonist. The A. fumigatus UgmA (AfUgmA crystal structure has been determined. From that study, AfUgmA mutants with altered enzyme activity were transformed into AnugmA▵ to assess their effect on growth and wall composition in A. nidulans. The complemented (AnugmA::wild type AfugmA strain had wild type phenotype, indicating these genes had functional homology. Consistent with in vitro studies, AfUgmA residues R182 and R327 were important for its function in vivo, with even conservative amino (RK substitutions producing AnugmA? phenotype strains. Similarly, the conserved AfUgmA loop III histidine (H63 was important for Galf generation: the H63N strain had a partially rescued phenotype compared to AnugmA▵. Collectively, A. nidulans strains that hosted mutated AfUgmA constructs with low enzyme activity showed increased hyphal surface adhesion as assessed by binding fluorescent latex beads. Consistent with previous qPCR results, immunofluorescence and ELISA indicated that AnugmA▵ and AfugmA-mutated A. nidulans strains had increased α-glucan and decreased β-glucan in their cell walls compared to wild type and AfugmA-complemented strains. Like the AnugmA▵ strain, A. nidulans strains containing mutated AfugmA showed increased sensitivity to antifungal drugs, particularly Caspofungin. Reduced β-glucan content was correlated with increased Caspofungin sensitivity. Aspergillus nidulans wall Galf, α-glucan, and β-glucan content was correlated in A. nidulans hyphal walls, suggesting dynamic coordination between cell wall synthesis and cell wall integrity.

  1. Antiviral Potential of Algae Polysaccharides Isolated from Marine Sources: A Review

    Directory of Open Access Journals (Sweden)

    Azin Ahmadi

    2015-01-01

    Full Text Available From food to fertilizer, algal derived products are largely employed in assorted industries, including agricultural, biomedical, food, and pharmaceutical industries. Among different chemical compositions isolated from algae, polysaccharides are the most well-established compounds, which were subjected to a variety of studies due to extensive bioactivities. Over the past few decades, the promising results for antiviral potential of algae-derived polysaccharides have advocated them as inordinate candidates for pharmaceutical research. Numerous studies have isolated various algal polysaccharides possessing antiviral activities, including carrageenan, alginate, fucan, laminaran, and naviculan. In addition, different mechanisms of action have been reported for these polysaccharides, such as inhibiting the binding or internalization of virus into the host cells or suppressing DNA replication and protein synthesis. This review strives for compiling previous antiviral studies of algae-derived polysaccharides and their mechanism of action towards their development as natural antiviral agents for future investigations.

  2. Chemical features of Ganoderma polysaccharides with antioxidant, antitumor and antimicrobial activities.

    Science.gov (United States)

    Ferreira, Isabel C F R; Heleno, Sandrina A; Reis, Filipa S; Stojkovic, Dejan; Queiroz, Maria João R P; Vasconcelos, M Helena; Sokovic, Marina

    2015-06-01

    Ganoderma genus comprises one of the most commonly studied species worldwide, Ganoderma lucidum. However, other Ganoderma species have been also reported as important sources of bioactive compounds. Polysaccharides are important contributors to the medicinal properties reported for Ganoderma species, as demonstrated by the numerous publications, including reviews, on this matter. Yet, what are the chemical features of Ganoderma polysaccharides that have bioactivity? In the present manuscript, the chemical features of Ganoderma polysaccharides with reported antioxidant, antitumor and antimicrobial activities (the most studied worldwide) are analyzed in detail. The composition of sugars (homo- versus hetero-glucans and other polysaccharides), type of glycosidic linkages, branching patterns, and linkage to proteins are discussed. Methods for extraction, isolation and identification are evaluated and, finally, the bioactivity of polysaccharidic extracts and purified compounds are discussed. The integration of data allows deduction of structure-activity relationships and gives clues to the chemical aspects involved in Ganoderma bioactivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Polymer functionalized single-walled carbon nanotube composites and semi-fluorinated quaternary ammonium polymer colloids and coatings

    Science.gov (United States)

    Paul, Abhijit

    Scope and Method of Study: Current study focused on understanding of "wetting" and "dewetting" phenomena between surfaces of single-walled carbon nanotubes (SWCNT) which are lightly grafted with polymer chains by reversible-deactivation radical polymerization, when they are mixed with matrix chains of the same architecture as grafts. Effects of grafts to matrix chain lengths on SWCNT dispersion in matrix polymers were studied by measuring electrical conductivity, glass transition temperature, and storage and loss moduli of nanocomposites. Another area of work was to design semi-fluorinated copolymers with core-shell morphology by emulsion polymerization, study their catalytic activities for hydrolyses of Paraoxon, a toxic insecticide, in the forms of both colloidal dispersions and films, and to characterize the surfaces of the films by atomic force microscopy and by dynamic contact angle measurements. Findings and Conclusions: The glass transition temperature ( Tg) of polystyrene (PS) filled with SWCNT grafted with PS of different lengths increased from 99 to 109 °C at 6 wt% of SWCNT followed by a plateau. The heat capacity (DeltaCp ) at Tg continued to decrease only for the smallest chain length grafted PS nanocomposites. SWCNT/PS nanocomposites had low electrical conductivity and showed no percolation threshold due to the thick polymer coatings. A key finding was that the SWCNT surface can accommodate only a fixed numbers of styrene units. Similar results on change in Tg were obtained for SWCNT/PMMA nanocomposites when molecular weight of matrix (Mmatrix) ≥ molecular weight of grafts (Mgraft). No change in DeltaCp was observed for SWCNT/PMMA nanocomposites. "Wetting" to "dewetting" occurred Mmatrix/ Mgraft ≈ 1. For Mmatrix > Mgraft, electrical conductivity of nanocomposites reached the value of 10-9 S cm-1 at 1.0 wt% nanotube loading and had percolation threshold of electrical conductivity at ˜0.25 wt% SWCNT. Raman and UV-vis-NIR data confirmed that

  4. Biochemical And Genetic Modification Of Polysaccharides

    Science.gov (United States)

    Kern, Roger G.; Petersen, Gene R.; Richards, Gil F.

    1993-01-01

    Bacteriophages producing endopolysaccharase-type enzymes used to produce, isolate, and purify high yields of modified polysaccharides from polysaccharides produced by, and incorporated into capsules of, certain bacteria. Bacteriophages used in conversion of native polysaccharide materials into polymers of nearly uniform high molecular weight or, alternatively, into highly pure oligosaccharides. Also used in genetic selection of families of polysaccharides structurally related to native polysaccharide materials, but having altered properties. Resulting new polysaccharides and oligosaccharides prove useful in variety of products, including pharmaceutical chemicals, coating materials, biologically active carbohydrates, and drag-reducing additives for fluids.

  5. Photovoltaic performance of multi-wall carbon nanotube/PEDOT:PSS composite on the counter electrode of a dye-sensitized solar cell

    Science.gov (United States)

    Rhee, Yonghoon; Ko, Minjae; Jin, Hwayoung; Jin, Joon-Hyung; Min, Nam Ki

    2014-08-01

    A composite of poly(3,4-ethylendioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and multi-walled carbon nanotubes (MWCNTs) was cyclovoltametrically electropolymerized on a fluorine-doped tin oxide (FTO) substrate and used as a counter electrode for a dye-sensitized solar cell. The PEDOT:PSS-MWCNT composite film was investigated using scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The CV diagrams showed that the PEDOT:PSS-MWCNT composite film has better electro-catalytic activity for the I-/I3- redox reaction than the conventional platinized FTO. The best energy conversion efficiency was observed in EIS data with an MWCNT content of 0.002 wt %.

  6. Polyaniline/multi-walled carbon nanotubes composite with core-shell structures as a cathode material for rechargeable lithium-polymer cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Pan [School of Marine Science and Technology, Harbin Institute of Technology, Weihai 264209 (China); Han, Jia-Jun, E-mail: hanjiajunhitweihai@163.com [School of Marine Science and Technology, Harbin Institute of Technology, Weihai 264209 (China); Jiang, Li-Feng [Dalian Chemical Institute of Chinese Academy of Sciences, Dalian 116011 (China); Li, Zhao-Yu; Cheng, Jin-Ning [School of Marine Science and Technology, Harbin Institute of Technology, Weihai 264209 (China)

    2017-04-01

    Highlights: • The polyaniline multi-walled carbon nanotubes composite with core-shell structures was synthetized via in situ chemical oxidative polymerization, and the materials were characterized by physical and chemical methods. • The PANI/WMCNTs was synthetized via in situ chemical oxidative polymerization with core-shell structures. • The WMCNTs highly enhanced the conductivity of composites. • The comopsites were more conducive to the intercalation and deintercalation of anions and cations. • The much better performance as the cathode for lithium-ion cells was acquired for the composites. • The composites are low cost and eco-friendly which have a good prospect in future. - Abstract: The aniline was polymerized onto functionalized multi-walled carbon nanotubes in order to obtain a cathode material with core-shell structures for lithium batteries. The structure and morphology of the samples were investigated by Fourier transform infrared spectroscopy analysis, scanning electron microscope, transmission electron microscope and X-ray diffraction. The electrochemical properties of the composite were characterized by the cyclic voltammetry, the charge/discharge property, coulombic efficiency, and ac impedance spectroscopy in detail. At a constant current density of 0.2 C, the first specific discharge capacity of the reduced and oxidized PANI/WMCNTs were 181.8 mAh/g and 135.1 mAh/g separately, and the capacity retention rates were corresponding to 76.75% and 86.04% for 100 cycles with 99% coulombic efficiency. It was confirmed that the CNTs obviously enhanced the conductivity and electrochemical performance of polyaniline, and compared with the pure PANI, the reduced composite possessed a quite good performance for the cathode of lithium batteries.

  7. Structural characterization of a mixed-linkage glucan deficient mutant reveals alteration in cellulose microfibril orientation in rice coleoptile mesophyll cell walls

    Directory of Open Access Journals (Sweden)

    Andreia Michelle Smith-Moritz

    2015-08-01

    Full Text Available The CELLULOSE SYNTHASE-LIKE F6 (CslF6 gene was previously shown to mediate the biosynthesis of mixed-linkage glucan (MLG, a cell wall polysaccharide that is hypothesized to be a tightly associated with cellulose and also have a role in cell expansion in the primary cell wall of young seedlings in grass species. We have recently shown that loss-of-function cslf6 rice mutants do not accumulate MLG in most vegetative tissues. Despite the absence of a structurally important polymer, MLG, these mutants are unexpectedly viable and only show a moderate growth compromise compared to wild type. Therefore these mutants are ideal biological systems to test the current grass cell wall model. In order to gain a better understanding of the role of MLG in the primary wall, we performed in-depth compositional and structural analyses of the cell walls of three day-old rice seedlings using various biochemical and novel microspectroscopic approaches. We found that cellulose content as well as matrix polysaccharide composition was not significantly altered in the MLG deficient mutant. However, we observed a significant change in cellulose microfibril bundle organization in mesophyll cell walls of the cslf6 mutant. Using synchrotron source Fourier Transform Mid-Infrared Spectromicroscopy for high-resolution imaging, we determined that the bonds associated with cellulose and arabinoxylan, another major component of the primary cell was of grasses, were in a lower energy configuration compared to wild type, suggesting a slightly weaker primary wall in MLG deficient mesophyll cells. Taken together, these results suggest that MLG may influence cellulose deposition in mesophyll cell walls without significantly affecting anisotropic growth thus challenging MLG importance in cell wall expansion.

  8. Purification, characterization and antioxidant activities in vitro and in vivo of the polysaccharides from Boletus edulis bull.

    Science.gov (United States)

    Luo, Aoxue; Luo, Aoshuang; Huang, Jiandong; Fan, Yijun

    2012-07-05

    A water-soluble polysaccharide (BEBP) was extracted from Boletus edulis Bull using hot water extraction followed by ethanol precipitation. The polysaccharide BEBP was further purified by chromatography on a DEAE-cellulose column, giving three major polysaccharide fractions termed BEBP-1, BEBP-2 and BEBP-3. In the next experiment, the average molecular weight (Mw), IR and monosaccharide compositional analysis of the three polysaccharide fractions were determined. The evaluation of antioxidant activities both in vitro and in vivo suggested that BEBP-3 had good potential antioxidant activity, and should be explored as a novel potential antioxidant.

  9. Properties of polysaccharides in several seaweeds from Atlantic Canada and their potential anti-influenza viral activities

    Science.gov (United States)

    Jiao, Guangling; Yu, Guangli; Wang, Wei; Zhao, Xiaoliang; Zhang, Junzeng; Ewart, Stephen H.

    2012-06-01

    To explore the polysaccharides from selected seaweeds of Atlantic Canada and to evaluate their potential anti-influenza virus activities, polysaccharides were isolated from several Atlantic Canadian seaweeds, including three red algae ( Polysiphonia lanosa, Furcellaria lumbricalis, and Palmaria palmata), two brown algae ( Ascophyllum nodosum and Fucus vesiculosus), and one green alga ( Ulva lactuca) by sequential extraction with cold water, hot water, and alkali solutions. These polysaccharides were analyzed for monosaccharide composition and other general chemical properties, and they were evaluated for anti-influenza virus activities. Total sugar contents in these polysaccharides ranged from 15.4% (in U. lactuca) to 91.4% (in F. lumbricalis); sulfation level was as high as 17.6% in a polysaccharide from U. lactuca, whereas it could not be detected in an alikali-extract from P. palmaria. For polysaccharides from red seaweeds, the main sugar units were sulfated galactans (agar or carrageenan) for P. lanosa, F. lumbricalis, and xylans for P. palmata. In brown seaweeds, the polysaccharides largely contained sulfated fucans, whereas the polysaccharides in green seaweed were mainly composed of heteroglycuronans. Screening for antiviral activity against influenza A/PR/8/34 (H1N1) virus revealed that brown algal polysaccharides were particularly effective. Seaweeds from Atlantic Canada are a good source of marine polysaccharides with potential antiviral properties.

  10. Radiation processing of polysaccharides

    International Nuclear Information System (INIS)

    2004-11-01

    Radiation processing is a very convenient tool for imparting desirable effects in polymeric materials and it has been an area of enormous interest in the last few decades. The success of radiation technology for processing of synthetic polymers can be attributed to two reasons namely, their ease of processing in various shapes and sizes, and secondly, most of these polymers undergo crosslinking reaction upon exposure to radiation. In recent years, natural polymers are being looked at with renewed interest because of their unique characteristics, such as inherent biocompatibility, biodegradability and easy availability. Traditionally, the commercial exploitation of natural polymers like carrageenans, alginates or starch etc. has been based, to a large extent, on empirical knowledge. But now, the applications of natural polymers are being sought in knowledge - demanding areas such as pharmacy and biotechnology, which is acting as a locomotive for further scientific research in their structure-function relationship. Selected success stories concerning radiation processed natural polymers and application of their derivatives in the health care products industries and agriculture are reported. This publication will be of interest to individuals at nuclear institutions worldwide that have programmes of R and D and applications in radiation processing technologies. New developments in radiation processing of polymers and other natural raw materials give insight into converting them into useful products for every day life, human health and environmental remediation. The book will also be of interest to other field specialists, readers including managers and decision makers in industry (health care, food and agriculture) helping them to understand the important role of radiation processing technology in polysaccharides

  11. Chemical Methods for the Determination of Soluble and Insoluble Non-Starch Polysaccharides - Review

    Directory of Open Access Journals (Sweden)

    Rodica Căpriţă

    2011-10-01

    Full Text Available Polysaccharides are macromolecules of monosaccharides linked by glycosidic bonds. Non-starch polysaccharides(NSP are principally non-α-glucan polysaccharides of the plant cell wall. They are a heterogeneous group ofpolysaccharides with varying degrees of water solubility, size, and structure. The water insoluble fiber fractioninclude cellulose, galactomannans, xylans, xyloglucans, and lignin, while the water-soluble fibers are the pectins,arabinogalactans, arabinoxylans, and β-(1,3(1,4-D-glucans (β-glucans. Both the enzymatic-gravimetric andenzymatic-chemical methods used for the determination of soluble and insoluble non-starch polysaccharides haveundergone a number of modifications and improvements, most occurring over the last 20 years.

  12. Combined effects of pectic enzymes on the degradation of pectin polysaccharides of banana fruit

    International Nuclear Information System (INIS)

    Jheng, G.; Jiang, Y.; Ghen, Y.; Yang, S.

    2011-01-01

    Pectin polysaccharide is one of the major components of the primary cellular wall in the middle lamella of plant tissues. The degradation of pectin polysaccharide contributes to fruit softening. In this study, water-soluble pectin (WSP) and acid-soluble pectin (ASP) were isolated from pulp tissues of banana fruit at various ripening stages, and combinations of the enzymes such as polygalcturonase (PG), pectin methylesterase (PME) and beta-galactosidase (beta-Gal) were used to investigate the effect on the degradation of WSP and ASP. PG promoted the degradation of pectin polysaccharides, especially in ASP. An enhanced effect of the degradation of WSP and ASP from various ripening banana fruit was observed in the presence of PME. In addition, beta-Gal accelerated slightly the degradation of WSP and ASP in the presence of PG. Overall, PG, PME and beta-Gal can coordinate to promote the degradation of pectin polysaccharides of banana fruit, resulting in fruit softening. (author)

  13. Fabrication of photocatalytic composite of multi-walled carbon nanotubes/TiO{sub 2} and its application for desulfurization of diesel

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Thu Ha Thi, E-mail: ptntd2004@yahoo.fr [Vietnam Institute of Industrial Chemistry, Hanoi (Viet Nam); Nguyen, Thu Trang Thi; Nguyen, Phuong Hoa Thi; Do, Manh Hung; Au, Hang Thi [Vietnam Institute of Industrial Chemistry, Hanoi (Viet Nam); Nguyen, Thanh Binh [Faculty of Chemistry, Hanoi University of Science, Vietnam National University, Hanoi (Viet Nam); Nguyen, Dinh Lam [Faculty of Chemical Engineering, Danang University of Technology, University of Danang (Viet Nam); Park, Jun Seo [Division of Chemical Engineering, Hankyong National University, Ansung 456-749 (Korea, Republic of)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer MWNTs and TiO{sub 2} were mixed well, forming uniform microstructure in MWNTs/TiO{sub 2} composites. Black-Right-Pointing-Pointer The combination of MWNTs and TiO{sub 2} contribute to improving photocatalytic activity of TiO{sub 2}. Black-Right-Pointing-Pointer MWNTs/TiO{sub 2} composite is an effective photo-catalyst for the removal of sulfur from commercial diesel. -- Abstract: Composite of multi-walled carbon nanotubes (MWNTs) and titanium (IV) oxide (TiO{sub 2}) were prepared by a heterogeneous gelation method. The activities of the MWNTs/TiO{sub 2} composites were evaluated by photocatalytic oxidative desulfurization using dibenzothiophene (DBT), 4,6-dimethyl dibenzothiophene (4,6-DMDBT), n-tetradecane, and commercial diesel under irradiation using a high-pressure Hg lamp. The microstructures of MWNTs/TiO{sub 2} composites were characterized by N{sub 2} adsorption, scanning electron microscopy, transmission electron microscope, and X-ray diffraction. It was found that more than 98% of sulfur compounds in commercial diesel were oxidized and removed by the use of the MWNTs/TiO{sub 2} composite as a photocatalyst.

  14. Fabrication of photocatalytic composite of multi-walled carbon nanotubes/TiO2 and its application for desulfurization of diesel

    International Nuclear Information System (INIS)

    Vu, Thu Ha Thi; Nguyen, Thu Trang Thi; Nguyen, Phuong Hoa Thi; Do, Manh Hung; Au, Hang Thi; Nguyen, Thanh Binh; Nguyen, Dinh Lam; Park, Jun Seo

    2012-01-01

    Highlights: ► MWNTs and TiO 2 were mixed well, forming uniform microstructure in MWNTs/TiO 2 composites. ► The combination of MWNTs and TiO 2 contribute to improving photocatalytic activity of TiO 2 . ► MWNTs/TiO 2 composite is an effective photo-catalyst for the removal of sulfur from commercial diesel. -- Abstract: Composite of multi-walled carbon nanotubes (MWNTs) and titanium (IV) oxide (TiO 2 ) were prepared by a heterogeneous gelation method. The activities of the MWNTs/TiO 2 composites were evaluated by photocatalytic oxidative desulfurization using dibenzothiophene (DBT), 4,6-dimethyl dibenzothiophene (4,6-DMDBT), n-tetradecane, and commercial diesel under irradiation using a high-pressure Hg lamp. The microstructures of MWNTs/TiO 2 composites were characterized by N 2 adsorption, scanning electron microscopy, transmission electron microscope, and X-ray diffraction. It was found that more than 98% of sulfur compounds in commercial diesel were oxidized and removed by the use of the MWNTs/TiO 2 composite as a photocatalyst.

  15. Target or barrier? The cell wall of early- and later- diverging plants vs cadmium toxicity: differences in the response mechanisms

    Directory of Open Access Journals (Sweden)

    Luigi eParrotta

    2015-03-01

    Full Text Available Increasing industrialization and urbanization result in emission of pollutants in the environment including toxic heavy metals, as cadmium and lead. Among the different heavy metals contaminating the environment, cadmium raises great concern, as it is ecotoxic and as such can heavily impact ecosystems. The cell wall is the first structure of plant cells to come in contact with heavy metals. Its composition, characterized by proteins, polysaccharides and in some instances lignin and other phenolic compounds, confers the ability to bind non-covalently and/or covalently heavy metals via functional groups. A strong body of evidence in the literature has shown the role of the cell wall in heavy metal response: it sequesters heavy metals, but at the same time its synthesis and composition can be severely affected. The present review analyzes the dual property of plant cell walls, i.e. barrier and target of heavy metals, by taking Cd toxicity as example. Following a summary of the known physiological and biochemical responses of plants to Cd, the review compares the wall-related mechanisms in early- and later-diverging land plants, by considering the diversity in cell wall composition. By doing so, common as well as unique response mechanisms to metal/cadmium toxicity are identified among plant phyla and discussed. After discussing the role of hyperaccumulators’ cell walls as a particular case, the review concludes by considering important aspects for plant engineering.

  16. Isolation, structural characterization and bioactivities of naturally occurring polysaccharide-polyphenolic conjugates from medicinal plants-A reivew.

    Science.gov (United States)

    Liu, Jun; Bai, Ruyu; Liu, Yunpeng; Zhang, Xin; Kan, Juan; Jin, Changhai

    2018-02-01

    In recent years, several medicinal plants have been demonstrated as valuable resources of naturally occurring polysaccharide-polyphenolic conjugates. For the first time, this article introduces recent advances of polysaccharide-polyphenolic conjugates isolated from different medicinal plants. The isolation, purification, structural characterization and biological activities of polysaccharide-polyphenolic conjugates are introduced in details. In general, polysaccharide-polyphenolic conjugates can be isolated by hot water or alkaline extraction followed by purification through anion exchange chromatography or gel filtration chromatography. The structures of conjugates are usually characterized by chemical composition analysis, UV-vis, Fourier-transform infrared and nuclear magnetic resonance spectroscopy. Moreover, polysaccharide-polyphenolic conjugates exhibit several biological activities including anticoagulant, antioxidant, radioprotective, anti-platelet, antitussive and bronchodilatory effects. Therefore, polysaccharide-polyphenolic conjugates isolated from medicinal plants are certain to have a bright prospect in the field of food and pharmaceutics. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. [Studies on difference between sporoderm-broken and nonbroken spores of Ganoderma lucidum (Leyss. ex Fr.) Karst. by polysaccharide analysis].

    Science.gov (United States)

    Bao, X F; Fang, J N

    2001-05-01

    To compare the release ability of water-soluble polysaccharides in sporoderm-broken and nonbroken spores of Ganoderma lucidum, and establish a comparatively correct method for the determination and analysis of polysaccharide contents in Chinese herbs. The release ability of water-soluble polysaccharides was determined on the basis of phenol-sulfuric acid modification in different conditions. The release ability of polysaccharides of sporoderm-broken spores was much greater than that of nonbroken spores; and the phenol-sulfuric acid modified cation method proved excellent in accuracy and reproducibility, with a relative error less than 1.5%. The spores should be wall-wracked if used as a nutriment, or for extraction and analysis of their effective components. The method can be successfully used for the determination of polysaccharide contents in Chinese herbs or nutriments.

  18. Organized polysaccharide fibers as stable drug carriers

    Science.gov (United States)

    Janaswamy, Srinivas; Gill, Kristin L.; Campanella, Osvaldo H.; Pinal, Rodolfo

    2013-01-01

    Many challenges arise during the development of new drug carrier systems, and paramount among them are safety, solubility and controlled release requirements. Although synthetic polymers are effective, the possibility of side effects imposes restrictions on their acceptable use and dose limits. Thus, a new drug carrier system that is safe to handle and free from side effects is very much in need and food grade polysaccharides stand tall as worthy alternatives. Herein, we demonstrate for the first time the feasibility of sodium iota-carrageenan fibers and their distinctive water pockets to embed and release a wide variety of drug molecules. Structural analysis has revealed the existence of crystalline network in the fibers even after encapsulating the drug molecules, and iota-carrageenan maintains its characteristic and reproducible double helical structure suggesting that the composites thus produced are reminiscent of cocrystals. The melting properties of iota-carrageenan:drug complexes are distinctly different from those of either drug or iota-carrageenan fiber. The encapsulated drugs are released in a sustained manner from the fiber matrix. Overall, our research provides an elegant opportunity for developing effective drug carriers with stable network toward enhancing and/or controlling bioavailability and extending shelf-life of drug molecules using GRAS excipients, food polysaccharides, that are inexpensive and non–toxic. PMID:23544530

  19. Atomic force microscopy stiffness tomography on living Arabidopsis thaliana cells reveals the mechanical properties of surface and deep cell-wall layers during growth.

    Science.gov (United States)

    Radotić, Ksenija; Roduit, Charles; Simonović, Jasna; Hornitschek, Patricia; Fankhauser, Christian; Mutavdžić, Dragosav; Steinbach, Gabor; Dietler, Giovanni; Kasas, Sandor

    2012-08-08

    Cell-wall mechanical properties play a key role in the growth and the protection of plants. However, little is known about genuine wall mechanical properties and their growth-related dynamics at subcellular resolution and in living cells. Here, we used atomic force microscopy (AFM) stiffness tomography to explore stiffness distribution in the cell wall of suspension-cultured Arabidopsis thaliana as a model of primary, growing cell wall. For the first time that we know of, this new imaging technique was performed on living single cells of a higher plant, permitting monitoring of the stiffness distribution in cell-wall layers as a function of the depth and its evolution during the different growth phases. The mechanical measurements were correlated with changes in the composition of the cell wall, which were revealed by Fourier-transform infrared (FTIR) spectroscopy. In the beginning and end of cell growth, the average stiffness of the cell wall was low and the wall was mechanically homogenous, whereas in the exponential growth phase, the average wall stiffness increased, with increasing heterogeneity. In this phase, the difference between the superficial and deep wall stiffness was highest. FTIR spectra revealed a relative increase in the polysaccharide/lignin content. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  20. Changes in the chemical properties and swelling coefficient of alfalfa root cell walls in the presence of toluene as a toxic agent.

    Science.gov (United States)

    Sharifi, M; Khoshgoftarmanesh, A H; Hadadzadeh, H

    2016-04-01

    The influence of toluene pollution on the chemical properties and swelling coefficient of root cell walls in alfalfa (Medicago sativa L.) was investigated. Two sets of alfalfa seedlings were selected and one set was treated with 450 mg L(-1) toluene in the nutrient solution under hydroponic culture. Thirty days after treatment with toluene, alfalfa plants were harvested and the root cell walls were isolated. Fourier-transform infrared (FTIR) spectroscopy was carried out for the characterization of the root cell walls composition. The cation exchange capacity (CEC) and the swelling coefficient of the root cell walls (Kcw) were estimated at various pH values. The toluene contamination significantly reduced the mass of the cell wall material in the alfalfa roots. According to the FTIR spectra, the toluene pollution can change the alfalfa root cell wall properties by reducing the cell wall functional groups. These functional groups are probably related to the proteins and polysaccharides in the cell wall. Also, toluene pollution strongly reduced CEC and Kcw of the root cell walls. The results show that the decrease in the active sites of adsorption on the root cell walls as a response to toluene pollution can affect the water flow rate and the mineral nutrients uptake by roots.

  1. Optimization of wall thickness and lay-up for the shell-like composite structure loaded by non-uniform pressure field

    Science.gov (United States)

    Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

    2017-01-01

    The glass/carbon fiber composites are widely used in the design of various aircraft and rotorcraft components such as fairings and cowlings, which have predominantly a shell-like geometry and are made of quasi-isotropic laminates. The main requirements to such the composite parts are the specified mechanical stiffness to withstand the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflow-induced vibrations at the constrained weight of the part. The main objective of present study is the optimization of wall thickness and lay-up of composite shell-like cowling. The present approach assumes conversion of the CAD model of the cowling surface to finite element (FE) representation, then its wind tunnel testing simulation at the different orientation of airflow to find the most stressed mode of flight. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. A wall thickness of the shell had to change over its surface to minimize the objective at the constrained weight. We used a parameterization of the problem that assumes an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. Curve that formed by the intersection of the shell with sphere defined boundary of area, which should be reinforced by local thickening the shell wall. To eliminate a local stress concentration this increment was defined as the smooth function defined on the shell surface. As a result of structural optimization we obtained the thickness of shell's wall distribution, which then was used to design the draping and lay-up of composite prepreg layers. The global strain energy in the optimized cowling was reduced in2

  2. Diamagnetic composite material structure for reducing undesired electromagnetic interference and eddy currents in dielectric wall accelerators and other devices

    Science.gov (United States)

    Caporaso, George J.; Poole, Brian R.; Hawkins, Steven A.

    2015-06-30

    The devices, systems and techniques disclosed here can be used to reduce undesired effects by magnetic field induced eddy currents based on a diamagnetic composite material structure including diamagnetic composite sheets that are separated from one another to provide a high impedance composite material structure. In some implementations, each diamagnetic composite sheet includes patterned conductor layers are separated by a dielectric material and each patterned conductor layer includes voids and conductor areas. The voids in the patterned conductor layers of each diamagnetic composite sheet are arranged to be displaced in position from one patterned conductor layer to an adjacent patterned conductor layer while conductor areas of the patterned conductor layers collectively form a contiguous conductor structure in each diamagnetic composite sheet to prevent penetration by a magnetic field.

  3. Immunomodulating activities of acidic sulphated polysaccharides obtained from the seaweed Ulva rigida C. Agardh.

    Science.gov (United States)

    Leiro, José M; Castro, Rosario; Arranz, Jon A; Lamas, Jesús

    2007-07-01

    Water-soluble acidic polysaccharides from the cell walls of Ulva rigida are mainly composed of disaccharides that contain glucuronic acid and sulphated rhamnose. The structure of disaccharides resembles that of glycosaminoglycans (GAGs) as they both contain glucuronic acid and sulphated sugars. Glycosaminoglycans occur in the extracellular matrix of animal connective tissues but can also be produced by leucocytes at inflammatory sites. Certain types of GAGs can even activate macrophages and therefore the acidic polysaccharides from U. rigida probably modulate macrophage activity. In the present study, we evaluated the effects of U. rigida polysaccharides on several RAW264.7 murine macrophage activities, including expression of inflammatory cytokines and receptors, nitric oxide and prostaglandin E2 (PGE(2)) production, and nitric oxide synthase 2 (NOS-2) and cyclooxygenase-2 (COX-2) gene expression. U. rigida acidic polysaccharides induced a more than two-fold increase in the expression of several chemokines (chemokine (C motif) ligand 1, chemokine (C-X-C motif) ligand 12, chemokine (C-C motif) ligand 22 and chemokine (C-X-C motif) ligand 14 (Cxcl14)) and in the expression of IL6 signal transducer and IL12 receptor beta 1. Incubation of macrophages with U. rigida polysaccharides also induced an increase in nitrite production, although this effect decreased considerably after desulphation of polysaccharides, suggesting that the sulphate group is important for the stimulatory capacity of these molecules. U. rigida polysaccharides also stimulated macrophage secretion of PGE(2) and induced an increase in COX-2 and NOS-2 expression. The results indicate that U. rigida acid polysaccharide can be used as an experimental immunostimulant for analysing inflammatory responses related to macrophage functions. In addition, these polysaccharides may also be of clinical interest for modifying certain macrophage activities in diseases where macrophage function is impaired or needs

  4. Synthesis and optimization of tin dioxide/functionalized multi-walled carbon nanotube composites as anode in lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xiao-Bing; Geng, Hong-Zhang, E-mail: genghz@tjpu.edu.cn; Meng, Yan; Ding, Er-Xiong; Wang, Yan; Zhang, Ze-Chen; Wang, Wen-Yi

    2015-03-01

    In this paper, nanocomposite electrodes for rechargeable Lithium-ion battery composed of tin dioxide (SnO{sub 2}) and multi-walled carbon nanotubes (MWCNTs) were prepared using the chemical deposition method with a subsequent sintering process. The as-prepared hybrids were characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The results showed that the size of pure SnO{sub 2} particles was ∼5 nm and hybrids presented a uniform dispersion of SnO{sub 2} nanoparticles on the surfaces of the MWCNTs. The electrochemical properties of the composites were researched through a cyclic voltammetry and a galvanostatic charge–discharge test. It was found that the electrochemical performance of the composite was strongly dependent on the content of MWCNTs in the composites. The SnO{sub 2}/MWCNT composite with 18.40 wt% MWCNTs gave the best performance, exhibiting a relatively higher reversible capacity of 475 mAh g{sup −1} and an extended capacity retention of 65% even after 30 cycles at a current density of 78.2 mA g{sup −1}. - Highlights: • SnO{sub 2}/MWCNT nanocomposites were prepared using chemical deposition method. • SnO{sub 2} nanoparticles presented a uniformly dispersion on the surfaces of MWCNTs. • SnO{sub 2}/MWCNT composite anode exhibited high reversible capacity for rechargeable Li-ion battery.

  5. Functionalized Multi walled Carbon Nano tubes-Reinforced Viny lester/Epoxy Blend Based Nano composites: Enhanced Mechanical, Thermal, and Electrical Properties

    International Nuclear Information System (INIS)

    Praharaj, A. P.; Behera, D.; Bastia, T. K.; Rout, A. K.

    2015-01-01

    This paper presents a study on the mechanical, thermal, and electrical characterization of a new class of low cost multiphase nano composites consisting of Vinyl ester resin/epoxy (VER/EP) blend (40:60 w/w) reinforced with amine functionalized multi walled carbon nano tubes (f-MWCNTs). Five different sets of VER/EP nano composites are fabricated with addition of 0, 1, 3, 5, and 7 wt.% of f-MWCNTs. A detailed investigation of mechanical properties like tensile strength, impact strength, Young’s modulus, and hardness, thermal properties like thermogravimetric analysis (TGA) and thermal conductivity, electrical properties like dielectric strength, dielectric constant, and electrical conductivity, and corrosive and swelling properties of the nano composites has been carried out. Here, we report significant improvement in all the above properties of the fabricated nano composites with nano filler (f-MWCNTs) addition compared to the virgin blend (0 wt. nano filler loading). The properties are best observed in case of 5 wt.% nano filler loading with gradual deterioration thereafter which may be due to the nucleating tendency of the nano filler particles. Thus the above nano composites could be a preferable candidate for a wide range of structural, thermal, electrical, and solvent based applications.

  6. Synthesis and optimization of tin dioxide/functionalized multi-walled carbon nanotube composites as anode in lithium-ion battery

    International Nuclear Information System (INIS)

    Xu, Xiao-Bing; Geng, Hong-Zhang; Meng, Yan; Ding, Er-Xiong; Wang, Yan; Zhang, Ze-Chen; Wang, Wen-Yi

    2015-01-01

    In this paper, nanocomposite electrodes for rechargeable Lithium-ion battery composed of tin dioxide (SnO 2 ) and multi-walled carbon nanotubes (MWCNTs) were prepared using the chemical deposition method with a subsequent sintering process. The as-prepared hybrids were characterized by thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The results showed that the size of pure SnO 2 particles was ∼5 nm and hybrids presented a uniform dispersion of SnO 2 nanoparticles on the surfaces of the MWCNTs. The electrochemical properties of the composites were researched through a cyclic voltammetry and a galvanostatic charge–discharge test. It was found that the electrochemical performance of the composite was strongly dependent on the content of MWCNTs in the composites. The SnO 2 /MWCNT composite with 18.40 wt% MWCNTs gave the best performance, exhibiting a relatively higher reversible capacity of 475 mAh g −1 and an extended capacity retention of 65% even after 30 cycles at a current density of 78.2 mA g −1 . - Highlights: • SnO 2 /MWCNT nanocomposites were prepared using chemical deposition method. • SnO 2 nanoparticles presented a uniformly dispersion on the surfaces of MWCNTs. • SnO 2 /MWCNT composite anode exhibited high reversible capacity for rechargeable Li-ion battery

  7. Preparation and property investigation of multi-walled carbon nanotube (MWCNT/epoxy composite films as high-performance electric heating (resistive heating element

    Directory of Open Access Journals (Sweden)

    F. X. Wang

    2018-04-01

    Full Text Available A series of multi-walled carbon nanotube (MWCNT/epoxy composite films with a thickness of ~700 µm is prepared by a sequential process of premixing, post dispersing, film casting, and thermal curing. The effects of the physical shear dispersion on the properties of conductive polymer composites as the electric heating element are investigated. The scanning electron microscope (SEM images show that highly efficient conductive networks form with shear dispersions of MWCNTs in the polymer matrix. The electrical resistivity decreases sharply from ~1015 Ω·cm for the neat epoxy resin to ~102 Ω·cm for the composite film with 2.0 wt% MWCNTs in accordance with the percolation behaviour, and a low percolation threshold of ~0.018 wt% is fitted. The electric heating behaviour of the composite film is observed at a low MWCNT content of 0.05 wt% due to the high electrical conductivity. For the composite film with 2.0 wt% MWCNTs, an equilibrium temperature of 115 °C is reached at an applied voltage of 40 V within 30 s. The excellent electric heating behaviour, including the rapid temperature response, electric heating efficiency, and operational stability, is primarily related to the conductive two-dimensional networks consisting of MWCNTs and the thermodynamically stable polymer matrix.

  8. Aleurone Cell Walls of Wheat Grain: High Spatial Resolution Investigation Using Synchrotron Infrared Microspectroscopy

    International Nuclear Information System (INIS)

    Jamme, F.; Robert, R.; Bouchet, B.; Saulnier, L.; Dumas, P.; Guillon, F.

    2008-01-01

    Infrared microspectroscopy and immunolabeling techniques were employed in order to obtain deeper insight into the biochemical nature of aleurone cell walls of wheat grain. The use of a synchrotron source, thanks to its intrinsic brightness, has provided unprecedented information at the level of a few micrometers and has allowed the discrimination of various polysaccharides in cell walls. The high spectral quality obtained in the small analyzed domain has been beneficial in estimating the relative proportions of Β-glucan and arabinoxylan, through the use of principal component analysis (PCA). The highest amount of Β-glucan is found in periclinal cell walls close to the starchy endosperm. The junction regions between aleurone cells are enriched in arabinoxylan. At the early stage of wheat grain development (271 degrees D), the chemical composition along the cell walls is more heterogeneous than at the mature stage. Both synchrotron infrared microspectroscopy and immunolabeling experiments made it possible to reveal the spatial heterogeneity of the various chemical compositions of aleurone cell walls.

  9. Functional multi-walled carbon nanotube/polysiloxane composite films as supports of PtNi alloy nanoparticles for methanol electro-oxidation

    International Nuclear Information System (INIS)

    Wang Zhicai; Ma Zhengming; Li Hulin

    2008-01-01

    We demonstrate the use of molecular monolayers to enhance the nucleation of electrocatalytically active PtNi alloy nanoparticles onto the multi-walled carbon nanotubes (MWCNTs). After the siloxane was polymerized on the nanotube surfaces, the carbon nanotubes were embedded within the polysiloxane shell with a hydrophilic amino group situated outside. Subsequent deposition of PtNi nanoparticles led to high density of 3-10 nm diameter PtNi alloy nanoparticles uniformly deposited along the length of the carbon nanotubes. The presence of MWCNTs and PtNi in the composite films was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersion X-ray spectra analysis (EDS). The electrocatalytic activity of the PtNi-modified MWCNT/polysiloxane (PtNi/Si-MWCNT) composite electrode for electro-oxidation of methanol was investigated by cyclic voltammetry (CV), and excellent electrocatalytic activity can be observed

  10. A clade in the QUASIMODO2 family evolved with vascular plants and supports a role for cell wall composition in adaptation to environmental changes.

    Science.gov (United States)

    Fuentes, Sara; Pires, Nuno; Østergaard, Lars

    2010-08-01

    The evolution of plant vascular tissue is tightly linked to the evolution of specialised cell walls. Mutations in the QUASIMODO2 (QUA2) gene from Arabidopsis thaliana were previously shown to result in cell adhesion defects due to reduced levels of the cell wall component homogalacturonic acid. In this study, we provide additional information about the role of QUA2 and its closest paralogues, QUASIMODO2 LIKE1 (QUL1) and QUL2. Within the extensive QUA2 family, our phylogenetic analysis shows that these three genes form a clade that evolved with vascular plants. Consistent with a possible role of this clade in vasculature development, QUA2 is highly expressed in the vascular tissue of embryos and inflorescence stems and overexpression of QUA2 resulted in temperature-sensitive xylem collapse. Moreover, in-depth characterisation of qua2 qul1 qul2 triple mutant and 35S::QUA2 overexpression plants revealed contrasting temperature-dependent stem development with dramatic effects on stem width. Taken together, our results suggest that the QUA2-specific clade contributed to the evolution of vasculature and illustrate the important role that modification of cell wall composition plays in the adaptation to changing environmental conditions, including changes in temperature.

  11. Polysaccharides in Human Health Care

    NARCIS (Netherlands)

    Dam, van J.E.G.; Broek, van den L.A.M.; Boeriu, C.G.

    2016-01-01

    Polysaccharides are abundant natural polymers found in plants, animals and microorganisms with exceptional properties and essential roles to sustain life. They are well known for their high nutritive value and the positive effects on our immune and digestive functions and detoxification system. The

  12. Effect of resin-modified glass-ionomer cement lining and composite layering technique on the adhesive interface of lateral wall

    Directory of Open Access Journals (Sweden)

    Larissa Marinho AZEVEDO

    2015-06-01

    Full Text Available Interface integrity can be maintained by setting the composite in a layering technique and using liners. Objective The aim of this in vitro study was to verify the effect of resin-modified glass-ionomer cement (RMGIC lining and composite layering technique on the bond strength of the dentin/resin adhesive interface of lateral walls of occlusal restorations. Material and Methods Occlusal cavities were prepared in 52 extracted sound human molars, randomly assigned into 4 groups: Group 2H (control – no lining + two horizontal layers; Group 4O: no lining + four oblique layers; Group V-2H: RMGIC lining (Vitrebond + two horizontal layers; and Group V-4O: RMGIC lining (Vitrebond + four oblique layers. Resin composite (Filtek Z250, 3M ESPE was placed after application of an adhesive system (Adper™ Single Bond 2, 3M ESPE dyed with a fluorescent reagent (Rhodamine B to allow confocal microscopy analysis. The teeth were stored in deionized water at 37oC for 24 hours before being sectioned into 0.8 mm slices. One slice of each tooth was randomly selected for Confocal Laser Scanning Microscopy (CLSM analysis. The other slices were sectioned into 0.8 mm x 0.8 mm sticks to microtensile bond strength test (MPa. Data were analyzed by two-way ANOVA and Fisher's test. Results There was no statistical difference on bond strength among groups (p>0.05. CLSM analysis showed no significant statistical difference regarding the presence of gap at the interface dentin/resin among groups. Conclusions RMGIC lining and composite layering techniques showed no effect on the microtensile bond strength and gap formation at the adhesive interface of lateral walls of high C-factor occlusal restorations.

  13. Structural features and water holding capacities of pressed potato fibre polysaccharides

    NARCIS (Netherlands)

    Ramasamy, U.; Kabel, M.A.; Schols, H.A.; Gruppen, H.

    2013-01-01

    Pressed potato fibre (PPF) has a high water holding capacity (WHC) affecting its processing as an animal feed. The aim of this study was to characterize cell wall polysaccharides (CWPs) in PPF and investigate their WHC. This was done via sequential extractions. Half of all