Search results for "cellulose"
showing 10 items of 318 documents
Use of two-dimensional thin-layer chromatography for the components study of poly(adenosine diphosphate ribose)
1990
Two-dimensional thin-layer chromatography on cellulose plates has been used for separating and quantifying the three adenosine derivatives: AMP, phosphoribosyl AMP (PRAMP), and (PR)2AMP obtained by venom phosphodiesterase digestion of poly(ADP-ribose). In vitro synthesized polymer, up to 300 derivatives in length were studied. Some parameters of the complexity of poly(ADP-ribose) could be deduced from our results: (i) The first branching point appears in fragments of approximately 21 derivatives in length. (ii) The branching points are located at regular distances of approximately 41 derivatives from each other.
Comparison of Water Adsorption Properties of Cellulose and Cellulose Nanocrystals Studied by Near-Infrared Spectroscopy and Gravimetry
2017
The adsorption properties of water molecules on cellulose and cellulose nanocrystals (CNCs), isolated from defatted rice bran (DRB) by 55% sulfuric acid hydrolysis under sonication were investigated. The powdered samples of cellulose and CNCs were analysed by using near infrared spectroscopy (NIR) and gravimetry at 38% and 55% humidities. Small amounts of samples were dried under vacuum at 120°C and the NIR spectra of the dry samples and their spectra during the adsorption water molecules were measured by using an NIR spectrometer equipped with a transflectance accessory and a DTGS detector. The quantitative adsorption of water molecules by the samples was determined by gravimetry. Second a…
Environmentally sustainable production of cellulose-based superabsorbent hydrogels
2006
The development of new products and materials, especially those which are non-petrolchemical reserves and based on renewable organic resources, using innovative sustainable processes is nowadays of increasing interest and deserves the attention of both academic and industrial research. Cellulose and its derivatives, as renewable organic resources, have been used to synthesize novel superabsorbent hydrogels. Although the production of cellulose is one of the causes connected to deforestation, the production of suitably engineered cellulose superabsorbent hydrogel materials has been proposed to preserve water in typically arid areas in the world. Paradoxically, divinylsulfone (DVS), a small d…
Formation and function of a complement-activating enzyme generated from factors of guinea pig serum and cobra venom
1971
An enzymatic complex can be formed by factors from guinea pig serum and cobra venom, which is able to activate C3 bypassing C1, C4 and C2. Formation and action of the enzyme are described. The action on C3 results in an activation of the terminal complement components and in membrane destruction provided suitable membrane receptors are available.
A xyloglucan from persimmon fruit cell walls
1998
Persimmon (Diospyros kaki L.) fruit cell walls have been shown to contain a high proportion of xyloglucan. This hemicellulosic polysaccharide appears to play a crucial role in the softening process that accompanies fruit ripening. In the present work, xyloglucan from persimmon fruit cell walls was extracted, purified and chemically characterized from alkali-extracted hemicelluloses. Monosaccharide analysis of purified xyloglucan showed a molar ratio of Glc:Xyl:Gal:Fuc of 10.0:6.0:3.4:1.4. Linkage analysis showed a high proportion of terminal residues, indicating a low degree of polymerization of side-chains.
Interactions between cationic amylose derivatives and a pulp fiber model surface studied by molecular modelling
2007
This study was performed in order to obtain more information about the interactions between pulp fibers and acetylated cationic starch derivatives on a molecular scale. The adsorption of the polymers on the fiber surface was studied by simulating polymers on a fiber model surface at 300 K. Fractional atomic coordinates of regenerated cellulose II were used to generate a cellulose fiber surface model. Carboxylate groups were added on the cellulose surface to represent the anionic charge of pulp fiber which originates from hemicelluloses. Amylose chains cationized and acetylated atom by atom were chosen to represent four different starch derivatives. Atomic charges used in simulations were ca…
Study of the factors influencing the bioaccessibility of 10 elements from chocolate drink powder
2016
Abstract A risk/benefit assessment of chocolate drink powder has been conducted by evaluating the total contents and the bioaccessibilities of Al, Ba, Cd, Cr, Cu, Fe, Mg, Mn, P and Zn. The bioaccessibility was studied considering the type of sample (traditional, light, diet and organic) and the different factors that may affect it, including physical-chemical parameters of the human digestive process (gastric pH, concentration of bile salts and presence of lipase) and the presence of dietary components (phytate, pectin, cellulose and tannin). The bioaccessibility varied greatly according to the sample type, being greater in the diet and organic samples, and on the element being considered (…
Untersuchungen zum oxidativen Abbau nativer Cellulose, 2. Einfluß der Alkalibehandlung auf die Viskositäts-Molekulargewichts-Beziehungen
1974
Um die Kinetik des oxidativen Abbaus nativer Cellulose viskosimetrisch verfolgen zu konnen, mussen neue [η]-M-Eichbeziehungen aufgestellt werden, da die Behandlung der Cellulose mit konzentriertem Alkali den Staudingerindex [η] erniedrigt, ohne das Molekulargewicht M zu verandern. Es wurden zwei Reihen oxidativ abgebauter, verschieden lange mit Alkali vorbehandelter Cellulosen hergestellt und an diesen die Konstanten der Kuhn-Mark-Houwink-Gleichung fur die Cellulosenitrate in Aceton und die Cellulosen in Cuoxam (Cu(NH3)4(OH)2) durch Vergleich mit Lichtstreuungsmessungen bestimmt. For kinetic studies of cellulose degradation by molecular oxygen it is necessary to establish new [η]-M-relation…
Über Molekulargewichte und Molekulargewichtsverteilungen nativer Cellulosen
1954
Ziel der vorliegenden Arbeit ist die Bestimmung der Grose und der Grosenverteilung der im nativen Pflanzenmaterial vorliegenden glukosidischen Ketten der Cellulose. Zur Gewinnung dieser Ketten wird das Pflanzenmaterial einer Extraktion mit organischen Losungsmitteln und mit 2%iger Natronlauge unterworfen und anschliesend polymeranalog nitriert. Die einzelnen Schritte des praparativen Verfahrens werden im Hinblick auf ihre mogliche Abbauwirkung durch Variation samtlicher Versuchsbedingungen kontrolliert. Es wird gezeigt, das das angewandte Verfahren die ursprunglich vorhandene Kett enlange und Kettenlangenverteilung weitgehend unverandert last. Die Bestimmung des Polymerisationsgrades erfolg…
Absolutes Molekulargewicht der nativen Cellulose der Alge Valonia
1976
Der Polymerisationsgrad der nativen Cellulose der Alge Valonia wurde bei dem unfraktionierten Material zu Pw≈26500 und bei dem durch Fallungsfraktionierung isolierten hochmolekularen Anteil der Molekulargewichtsverteilung zu Pw≈44000 ermittelt. Diese letzte Grose legt die Dimension fest, die die synthetisierende Matrize geometrisch erfullen mus. Sie durfte um einen Faktor von ca. 3 groser sein als die bei der Baumwollcellulose mit Pw≈14000. In Verbindung mit anderen Untersuchungen wird eine Biosynthese des Cellulosemolekuls als sehr wahrscheinlich angesehen, die direkt auf einer flachenformigen Matrize zu einer gefalteten Kette fuhrt. Da die thermodynamisch kontrollierte Faltungslange zu me…