The optical rotation of wood xylans

Gutmann, P. J.; Timell, T. E.

doi:10.1002/polc.5070110120

Cited by 6 publications

(3 citation statements)

References 19 publications

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“…The specific optical rotation of extracted xylan matches well with the commercial xylan and confirms that the extracted xylan is composed of α-linked d -glucuronic acid and β-linked d -xylose monosugar. Similar results for different xylans extracted from wood were reported by Gutmann and Timell . The elemental composition analysis of extracted xylan showed that it contains 36.70% carbon content and 3.92% hydrogen content, while the nitrogen and sulfur content are absent in the extracted xylan, confirming that the extracted xylan is highly pure.…”

Section: Results and Discussionsupporting

confidence: 88%

“…Similar results for different xylans extracted from wood were reported by Gutmann and Timell. 29 The elemental composition analysis of extracted xylan showed that it contains 36.70% carbon content and 3.92% hydrogen content, while the nitrogen and sulfur content are absent in the extracted xylan, confirming that the extracted xylan is highly pure.…”

Section: Resultsmentioning

confidence: 87%

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Acacia Xylan as a Substitute for Commercially Available Xylan and Its Application in the Production of Xylooligosaccharides

et al. 2020

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Over the past two decades, birchwood and beechwood xylans have been used as a popular substrate for the characterization of xylanases. Recently, major companies have discontinued their commercial production. Therefore, there is a need to find an alternative to these substrates. Xylan extraction from Acacia sawdust resulted in 23.5% (w/w) yield. The extracted xylan is composed of xylose and glucuronic acid residues in a molar ratio of 6:1 with a molecular mass of ∼70 kDa. The specific optical rotation analysis of extracted xylan displayed that it is composed of the d-form of xylose and glucuronic acid monomeric sugars. The nuclear magnetic resonance analysis of extracted xylan revealed that the xylan backbone is substituted with 4-O-methyl glucuronic acid at the O2 position. Fourier transform infrared analysis confirmed the absence of lignin contamination in the extracted xylan. Xylanase from Clostridium thermocellum displayed the enzyme activity of 1761 U/mg against extracted xylan, and the corresponding activity against beechwood xylan was 1556 U/mg, which confirmed that the extracted xylan could be used as an alternative substrate for the characterization of xylanases.

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Section: Results and Discussionsupporting

confidence: 88%

Section: Resultsmentioning

confidence: 87%

Acacia Xylan as a Substitute for Commercially Available Xylan and Its Application in the Production of Xylooligosaccharides

et al. 2020

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“…One would therefore expect, on this model, to find carrier mobilities in polymers increasing with molecular weight. Such an effect has been predicted by Gutmann 38 on the basis of a computer study of residual long-range order in polymers. He finds that the spatial extent of such order is proportional to (molecular weight)* and proposes the formation of energy bands which, although fairly wide, are localized in both space and time.…”

Section: Results a N D Discussionmentioning

confidence: 79%

Charge transfer in paraffinic hydrocarbons under the influence of external electric fields

Fleming¹

1970

Trans. Faraday Soc.

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Two papers treating electrical conductivity in organic solids, by McCubbin and Eley and Willis, art: discussed and the approaches therein modified and combined in a first-order time-independent perturbation treatment of electrical conductivity in the paraffinic hdyrocarbon octacosane (CZSH58). Extrinsic conductivity is assumed, electrons moving within one-dimensional wells of width comparable to the length of the molecule, and of depth slightly less than its ionization potential. The electrons tunnel through potential barriers between neighbouring molecules. Electron mobilities in the range 50-100 cm2/V s are deduced for paraffins containing twenty or more carbon atoms and for polymers such as polyethylene. This result agrees with an estimate of hole mobility in polyethylene published by McCubbin and Gurney using conventional band theory. Since tunnelling and hopping models of conduction are generally considered to apply when carrier mobilities do not exceed approximately 1 cm2/V s, it would therefore appear that, in the absence of reliable experimental mobility data for polymers, the charge transfer properties of such materials are more properly described in terms of the familiar energy-band formation concepts.

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Behaviors of southern red oak hemicelluloses and lignin in a mild sulfuric acid hydrolysis

Tran

Chambers

1986

Biotech & Bioengineering

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Removal and modification of southern red oak hemicelluloses and lignin in a 0.05%(w/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150 degrees C for in 38 min and to extend the hydrolysis at 150 degrees C for 1 h. At the end of the hydrolysis, 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded from room temperature to 150 degrees C, a part of red oak xylan was removed to yield an oligomer fraction having maximal yield and average molecular weight of 3460 at 150 degrees C. This fraction and the bulk xylan extracted during the first 30 min at 150 degrees C were further degraded to give a lower molecular weight oligomer fraction, of which the yield and average molecular weight (2610) were highest at the end of the bulk removal of xylan. Red oak lignin, syringyl and guaiacyl units in particular, was increasingly removed with the progress of the hydrolysis. Lignin derivatives and a part of red oak extractives soluble in the hydrolysate were identified.

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The optical rotation of wood xylans

Cited by 6 publications

References 19 publications

Acacia Xylan as a Substitute for Commercially Available Xylan and Its Application in the Production of Xylooligosaccharides

Acacia Xylan as a Substitute for Commercially Available Xylan and Its Application in the Production of Xylooligosaccharides

Charge transfer in paraffinic hydrocarbons under the influence of external electric fields

Behaviors of southern red oak hemicelluloses and lignin in a mild sulfuric acid hydrolysis

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