A5040694983- Advanced Cellulose Research Studies
- Lignin and Wood Chemistry
- Polysaccharides and Plant Cell Walls
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Biofuel production and bioconversion
- Nanocomposite Films for Food Packaging
- Material Properties and Processing
- Electrospun Nanofibers in Biomedical Applications
- Studies on Chitinases and Chitosanases
- Catalysis for Biomass Conversion
- Crystallography and molecular interactions
- Food composition and properties
- Fungal Biology and Applications
- Antifungal resistance and susceptibility
- Enzyme Structure and Function
- Dyeing and Modifying Textile Fibers
- Polysaccharides Composition and Applications
- biodegradable polymer synthesis and properties
- Carbohydrate Chemistry and Synthesis
- Wood Treatment and Properties
- Natural Fiber Reinforced Composites
- Silk-based biomaterials and applications
- Advanced Materials and Mechanics
- Surfactants and Colloidal Systems
Centre de Recherches sur les Macromolécules Végétales
2014-2024
Centre National de la Recherche Scientifique
2015-2024
Université Grenoble Alpes
2014-2024
Université Joseph Fourier
2007-2022
Centre National pour la Recherche Scientifique et Technique (CNRST)
2022
Teikyo University
1992-2018
Ahvaz Jundishapur University of Medical Sciences
2018
Isfahan University of Medical Sciences
2018
Tehran University of Medical Sciences
2018
Google (United States)
2017
The crystal and molecular structure together with the hydrogen-bonding system in cellulose Ibeta has been determined using synchrotron neutron diffraction data recorded from oriented fibrous samples prepared by aligning microcrystals tunicin. These diffracted both X-rays neutrons to better than 1A resolution (>300 unique reflections; P2(1)). X-ray were used determine C O atom positions. resulting consisted of two parallel chains having slightly different conformations organized sheets packed...
Never-dried and once-dried hardwood celluloses were oxidized by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated system, highly crystalline individualized cellulose nanofibers, dispersed in water, prepared mechanical treatment of the cellulose/water slurries. When carboxylate contents formed from primary hydroxyl groups reached approximately 1.5 mmol/g, slurries mostly converted to transparent viscous dispersions treatment. Transmission electron microscopic observation showed...
Never-dried native celluloses (bleached sulfite wood pulp, cotton, tunicin, and bacterial cellulose) were disintegrated into individual microfibrils after oxidation mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical followed a homogenizing mechanical treatment. When oxidized with 3.6 mmol of NaClO per gram cellulose, almost totality pulp cotton readily long treatment Waring Blendor, yielding transparent highly viscous suspensions. observed transmission electron microscopy,...
The crystal and molecular structure, together with the hydrogen-bonding system in cellulose Iα, has been determined using atomic-resolution synchrotron neutron diffraction data recorded from oriented fibrous samples prepared by aligning microcrystals cell wall of freshwater alga Glaucocystis nostochinearum. X-ray were used to determine C O atom positions. resulting structure is a one-chain triclinic unit all glucosyl linkages hydroxymethyl groups (tg) identical. However, adjacent sugar rings...
The shape and size distribution of crystalline nanoparticles resulting from the sulfuric acid hydrolysis cellulose cotton, Avicel, tunicate were investigated using transmission electron microscopy (TEM) atomic force (AFM) as well small- wide-angle X-ray scattering (SAXS WAXS). Images negatively stained cryo-TEM specimens showed that majority particles flat objects constituted by elementary crystallites whose lateral adhesion was resistant against sonication treatments. Moreover, tunicin...
A revised crystal structure for mercerized cellulose based on high-resolution synchrotron X-ray data collected from ramie fibers is reported (space group P21, a = 8.10(3) Å, b 9.03(3) c 10.31(5) γ 117.10(5)°; 751 reflections in 304 composite spots; θ < 21.11°; λ 0.7208 Å; LALS refinement with d > 1.5 R' ' 0.16; SHELX97 1 R 0.21). As regenerated the consists of antiparallel chains different conformations but hydroxymethyl groups both near gt position. However, conformation center chain here...
Lignocellulosic biomass, a potentially important renewable organic source of energy and chemical feedstock, resists degradation to glucose in industrial hydrolysis processes thus requires expensive thermochemical pretreatments. Understanding the mechanism biomass breakdown during these pretreatments will lead more efficient use biomass. By combining multiple probes structure, sensitive different length scales, with molecular dynamics simulations, we reveal two fundamental responsible for...
The crystal and molecular structure hydrogen bonding system in cellulose II have been revised using new neutron diffraction data extending to 1.2 Å resolution collected from two highly crystalline fiber samples of mercerized flax. Mercerization was achieved NaOH/H2O for one sample NaOD/D2O the other, corresponding labile hydroxymethyl moieties being hydrogenated deuterated, respectively. Fourier difference maps were calculated which amplitudes combined with phases X-ray models II, A B'....
The crystal and molecular structure, together with the hydrogen-bonding system in ammonia-mercerized cellulose IIII, has been determined using synchrotron X-ray neutron fiber diffraction data. structure a one-chain monoclinic unit cell an asymmetric that contains only one glucosyl residue hydroxymethyl group gt conformation. is well-defined no evidence of disorder. A bifurcated hydrogen bond links donating secondary alcohol O3 atom to ring O5 (major) primary O6 (minor) adjacent same chain....
A simple chemical modification route to confer high hydrophobicity crystalline cellulose surface was demonstrated using tunicin whiskers as model material. An alkyenyl succinic anhydride (ASA) aqueous emulsion mixed with suspension, freeze-dried, and heated 105 degrees C. The bulk degree of substitution (DS) evaluated by FT-IR spectrometry, elemental analysis, weight gain. DS quantified X-ray photoelectron spectroscopy. surface-acylated retained their morphological integrity, but due...
Small angle neutron scattering studies have been carried out on cellulose fibers from ramie and Populus maximowicii (cotton wood). Labile hydrogen atoms were replaced by deuterium atoms, in water-accessible disordered regions of the fibers, to increase contrast between crystalline regions. A meridional Bragg reflection, corresponding a longitudinal periodicity 150 nm, was observed when collected hydrogenated deuterated dry subtracted. No reflection with cotton wood probably because lower...
In the crystal structure of cellulose I beta, disordered hydrogen bonding can be represented by average two mutually exclusive schemes that have been designated A and B. An unanswered question is whether B interconvert dynamically, or they are static but present in different regions microfibril (giving temporally a spatially averaged structures, respectively). We used neutron crystallographic techniques to determine occupancies at 295 15 K, quantum mechanical calculations compare energies B,...
A temperature-sensitive, elongation-deficient mutant of Arabidopsis thaliana was isolated. At the non-permissive temperature 31°C, mutation impaired tissue elongation; otherwise, development normal. Hypocotyl cells that had established cell walls at 21°C under light-dark cycles ceased elongation and swelled when shifted to 31°C darkness, indicating affected gene is essential for elongation. Analysis plants grown revealed cellulose content reduced 40% pectin increased 162% corresponding...
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTCellulose Microcrystal Film of High Uniaxial OrientationNishiyama Yoshiharu, Kuga Shigenori, Wada Masahisa, and Okano TakeshiView Author Information Laboratory Structural Biopolymers, Department Biomaterial Sciences, Graduate School Agricultural Life The University Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan Cite this: Macromolecules 1997, 30, 20, 6395–6397Publication Date (Web):October 6, 1997Publication...
A new and highly efficient synthetic method has been developed for the surface esterification of model cellulosic substrates high crystallinity accessibility, namely, freeze-dried tunicin whiskers bacterial cellulose microfibrils dried by critical point method. The reaction, which is based on gas-phase action palmitoyl chloride, was monitored solid-state CP-MAS 13C NMR. It found that grafting density not only depended experimental conditions, but also nature conditioning samples. structural...
The synthesis of star-shaped polylactides (PLAs) having both poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) arms in one molecule, i.e., stereo-miktoarm PLAs, is described. azido-functionalized PDLAs ethynyl-functionalized PLLA possessing linear two- three-branched structures were prepared by the ring-opening polymerization d-lactide l-lactide using azido- or initiators. number-average molecular weights (Mn,NMRs) PLAs ca. 5000 g mol–1 with narrow weight distributions (Mw/Mns) less than...
The contribution of hydrogen bonds and the London dispersion force in cohesion cellulose is discussed light structure, spectroscopic data, empirical molecular-modelling parameters thermodynamics data analogue molecules. bond mainly electrostatic, stabilization energy for each estimated to be between 17 30 kJ mol-1 On average, hydroxyl groups form comparable those other simple alcohols. interaction may from attraction terms molecular modelling by integration over all components. Although this...
Abstract Silk fibroin–microcrystalline cellulose (cellulose whisker) composite films with varied compositions were prepared by casting mixed aqueous solution/suspensions of the two components. fibroin was dissolved in 10 M LiSCN followed dialysis; a whisker suspension sulfuric acid hydrolysis tunicate cellulose. Macroscopically homogeneous obtained at all mixing ratios. While Young's modulus showed linear, additive dependence on ratio, tensile strength and ultimate strain maximum 70–80%...
Agarose hydrogels filled with cellulose nanowhiskers were strained in uniaxial stretching under different humidity conditions. The orientation of the whiskers was examined before and after testing an X-ray laboratory source monitored situ during loading by synchrotron diffraction. aim this approach to determine process parameters for reorienting toward a preferential direction. Results show that controlled drying hydrogel is essential establish interactions between matrix which allow stress...