bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stabilizing Effect of Chromated Salt Treatment on the Green Color of Ma Bamboo (Dendrocalamus latiflorus)
Authors: Chang Shang-Tzen , Wu Jyh-Horng 
Published: October 2004

SummaryProcessed bamboo culms capable of maintaining the greenish color in their skin have increased economic value. The use of protectors to preserve the green color and to improve the color fastness of bamboo culms has, therefore, attracted great interest in the industry. In this paper three exposure tests, including accelerated UV lightfastness, outdoor weathering, and indoor exposure, were used to evaluate the color fastness of ma bamboo (Dendrocalamus latiflorusMunro) treated with chromium based reagents. Experimental results revealed that bamboo culms treated with CCP (chromated copper phosphate) or CP (chromated phosphate), both homemade by the authors, exhibited excellent color fastness. Among all inorganic salt-treated bamboo culms the CP-treated samples had the brighter greenish skin and also provided the best green color fastness. It was further noticed that ultraviolet light plays an important role on the color conversion of CrO3-treated bamboo. The green color becomes significantly enhanced with increased exposure time.
Dielectrically Observed Consequences of Microbial Treatment of Wood and Bamboo
Authors: Khan Muhammad Abdullah , Rizvi Tasneem Zahra , Abdullah Naheed , Zaheer Muhammad Yar , Iqbal Muhammad Zafar , Sadiq Shoaib 
Published: October 2004

Summary
Changes in dielectric constant and loss factor of two different species of wood namely Sheesham (Dalbergia
Sissoo) and Bamboo (Bambusa sp) are reported in the frequency range 30 Hz–3 MHz following
their microbial treatment with Coriolus versicolor. Comparison of dielectric data of C. versicolor treated
and untreated wood obtained in oven dried samples and in the samples exposed to atmospheric moisture
for more than 2 weeks reflect the alteration in chemical composition of the wood after C. versicolor
treatment and its associated altered hydration behaviour. In all the experiments described here the
principal feature of the frequency dependent dielectric response is a low frequency dispersion in ∈
∣
and
∈
∥
and a weak loss peak observed at a higher frequency. The low frequency dispersion is attributed to
localised hopping of charge carriers between neighbouring sites and the higher frequency peak to the
reorientation of polar sub molecular species of constituent molecules.
Comparative Studies of Hemicelluloses Solubilized during the Treatments of Maize Stems with Peroxymonosulfuric Acid, Peroxyformic Acid, Peracetic Acid, and Hydrogen Peroxide. Part 1. Yield and Chemical Characterization
Authors: Sun RunCang , Tomkinson J. , Geng Z. C. , Wang N. J. 
Published: October 2004

Summary
Treatment of the water-extracted maize stems with peroxymonosulfuric acid at 20 °C for 144 h, peroxyformic
acid at 80°C for 6 h, peracetic acid at 50°C for 6 h, and 2% hydrogen peroxide at 45°C for 12
h at pH 1.5, 4.4, 9.5, 11.5, 12.0, and 12.6, respectively, solubilized 47.1%, 91.3%, 33.3%, 16.6%,
15.9%, 17.4%, 86.2%, 87.7%, and 91.3% of the original lignin, and hydrolysed or dissolved 12.1%,
99.1%, 4.5%, 2.7%, 3.1%, 3.1%, 63.3%, 64.7%, and 83.0% of the original hemicelluloses, respectively.
Substantial lignins and hemicelluloses were degraded or released during the treatment with peroxyformic
acid and alkaline peroxide at pH ≥ 11.5, while an insignificant effect on delignification and
hemicellulose solubilization was observed by using peroxymonosulfuric acid, peracetic acid, and hydrogen
peroxide in acidic, natural, and weak alkaline media. The optimum condition for extraction of hemicelluloses
was found to use 2% H2O2 at 45°C for 12 h at pH 11.5–12.0, which yielded 63.3–64.7% of
the original hemicelluloses having much lighter color than those obtained by peroxymonosulfuric acid
and peracetic acid under conditions used and 2% H2O2 at pH 1.5, 4.4, 9.5, and 12.6. Xylose and arabinose
were the major sugar constituents in these hemicellulose preparations, whereas glucose, galactose,
mannose, rhamnose, and fucose were present as minor components. The α-ether linkages between lignin
and hemicelluloses in the cell wall of maize stems were substantially cleaved during the treatment with
2% H2O2 at pH ≥11.5 as shown by a minimal amount of associated lignin (2.9–3.9%), rich in syringyl
units, in the solubilized hemicelluloses.
Eucalyptus globulus Kraft Pulp Residual Lignins. Part 1. Effects of Extraction Methods upon Lignin Structure
Authors: Duarte Ana Paula , Robert Danielle , Lachenal Dominique 
Published: October 2004

Summary
Residual lignins of Eucalyptus globulus kraft pulp were shown to be structurally different depending
upon the type of extraction chosen. Enzymatic hydrolysis releases a residual lignin with a well preserved
etherified structure but substantially contaminated by protein and carbohydrate moieties coming from
the enzyme. Moreover, the extraction yield is poor and obviously it does not work as well as in the case
of softwood kraft pulp. The residual lignin extracted by acid hydrolysis has less etherified units and more
free phenolic functions than that of the enzymatic hydrolysis. It contains some unsaturated structures but
no carbohydrate contaminants. Comparison with Milled Wood Lignin (MWL) treated under the acid
hydrolysis conditions shows that ether splitting occurs during this extraction. The different residual
lignin fractions were characterised by HPSEC, FT-IR, 13C NMR and sugar analysis.
Lignin Behavior During the Autocatalyzed Methanol Pulping of Eucalyptus globulus Changes in Molecular Weight and Functionality
Authors: Gilarranz Miguel A. , Rodríguez Francisco , Oliet Mercedes 
Published: October 2004

Summary
The molecular weight distribution and functional group contents (phenolic and carbonyl) of lignin samples
from the autocatalyzed pulping of Eucalyptus globulus wood were determined. A total of 17 pulping
runs were carried out at different conditions according to a surface response design experimental
matrix (central composite). The influence of pulping temperature (170–200°C), pulping time
(40–120 min) and methanol concentration (30–70%, w/w) on the characteristics of the isolated lignins
was studied. Empirical models were developed and used to predict the lignin properties as a function of
the cooking conditions. Under high temperature, long cooking time and low alcohol concentration, a rise
in functional groups content and a drop in molecular weight of lignin
Lignin Degradation in Oxygen Delignification Catalysed by [PMo7V5O40]8- Polyanion. Part I. Study on Wood Lignin
Authors: Evtuguin D.V. , Neto C. Pascoal , Rocha J. 
Published: October 2004

Summary
The behaviour of lignin in wood delignification by oxygen in acidic media in the presence of the molybdovanadophosphate
heteropolyanion [PMO7V5O40]8−as studied using wet chemistry methods, solid
and liquid state 13C NMR spectroscopy. Lignin is oxidised by [PMO7V5O40]8− almost completely to
carbon dioxide, with a minor yield of intermediate low-molecular weight aromatic products. The analysis
of the reaction products shows that the lignin acidolysis and homolysis involving the oxygen participation
in oxidation take place. The residual lignin in the wood residue is more “condensed” and richer
in guaiacyl structural units than that in the initial wood. The analysis of “condensed” structures issued
from permanganate oxidation of residual lignins suggests that these are formed predominantly by acid-catalysed
reactions. The use of an organic solvent, such as ethanol, in the pulping solution favours the
oxidative delignification, protecting the lignin against competing reactions (condensation).
Biobleaching of Pulp with Dioxygen in the Laccase-Mediator System. Part 1. Kinetics of Delignification
Authors: Balakshin Mikhail , Chen Chen-Loung , Gratzl Josef S. , Kirkman Adrianna G. , Jakob Harald 
Published: October 2004

SummaryKinetics of pine kraft-AQ pulp delignification with the laccase-mediator system (LMS) and the effects of variable factors on the delignification were studied. The delignification was conducted in acetate buffer solution at pH 4.5 and at 40°C under atmospheric pressure. Only a part of the residual lignin could be removed in one-stage processes. Kinetics of kappa number reduction follows a pseudo-second order rate law with pulp consistency of 10 %, mediator charge of 0.1 mmole HOBT/g pulp and laccase charage of 10 UCorioluslaccase/g pulp. Kinetics of dioxygen uptake follows a pseudo-first order rate law up to first 8 hours of the reaction and a pseudo-zero order rate law at the reaction time of 8–24 hours. The amounts of dioxygen consumed per removal of one C9-unit equivalent of residual lignin is rather high, 1.5–2.5 mole, and increases with increasing reaction time. Experimental data show that side reactions between the Laccase-Mediator System and products of oxidative degradation of lignin strongly inhibit the delignification either by chemical or physical means or both. Removal of the degraded lignin fragments by alkaline extraction effectively restores the delignification of pulp with LMS. A four-stage process consisting of consecutive treatment of pulp with dioxygen-laccase-HOBT (LMS) followed by alkaline extraction (E), (LMS-E)4, decreased kappa number of a pine kraft-AQ pulp from 21.8 to less than 5. On the basis of the kinetic data, the mechanism of the pulp delignification with LMS is discussed.
Degradation of Model Compounds for Cellulose and Lignocellulosic Pulp during Ozonation in Aqueous Solution
Authors: Olkkonen Carola , Tylli Henrik , Forsskåhl Ingegerd , Fuhrmann Agneta , Hausalo Tiina , Tamminen Tarja , Hortling Bo , Janson Jan 
Published: October 2004

Summary
Ozonations of methylpyranosides, as model compounds for cellulose, were performed in unbuffered
aqueous solution at room temperature. The degradation of the pyranosides was followed spectrophotometrically
and with high-performance liquid chromatography (HPLC) as a function of ozonation time.
The substrates studied were the α- and β-anomers of methyl-D-glucopyranoside, methyl-D-mannopyranoside
and methyl-D-xylopyranoside. Methyl-α-D-xylopyranoside degraded more slowly than the other
compounds, whereas the rate of degradation was fastest for methyl-β-D-mannopyranoside. In general
the degradation of the α-anomers was slower than that of the corresponding β-anomers. HPLC and gas
chromatography—mass selective (GC-MS) analyses of the ozonated glucopyranoside samples showed
that monosaccharides, lactones, furanosides and acidic compounds are formed during ozonation.
A lignin-carbohydrate complex (LCC), containing a D-xylose unit connected to an aromatic part
through a βglycosidic bond, was used as a model compound for lignocellulosic pulp. The degradation
of this compound during ozonation was also investigated. The results from UV analyses showed that the
reaction was extremely fast at the beginning and that the degradation of benzene structures in the lignin
mimicking part of the LCC was very rapid. The degradation of the carbohydrate part was slower. This
suggests that lignin provides some protection for the cellulose in lignin-containing pulps against attack
by ozone. IR and NMR analyses of the freeze-dried ozonated LCC samples showed further that C=O
structures are produced during ozonation.
Application of a Catalyst in Peroxide Bleaching of Eucalyptus Kraft Pulp
Authors: Kühne L. , Odermatt J. , Wachter T. 
Published: October 2004

Summary
A binuclear [Mn(III)Mn(IV)(μ-O)2(μ-CH3COO)L](ClO4−)2 complex with L = 1,2 Bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane, described as a selective catalyst in hydrogen peroxide bleaching of
softwood pulps, was tested in hardwood kraft pulp bleaching. The catalyst application gave rise to a higher
consumption of peroxide which resulted in higher pulp brightness. The delignification improvement
caused by the catalyst was shown to be much lower compared to catalysed peroxide bleaching of softwood
kraft pulp. In contrast to the results of softwood pulp bleaching no selectivity improvements could
be found when using the catalyst in bleaching of eucalyptus kraft pulp.
Kinetic Study on Delignification of Kraft-AQ Pine Pulp with Hydrogen Peroxide Catalyzed by Mn(IV)-Me4DTNE
Authors: Cui Yu , Puthson Pratuang , Chen Chen-Loung , Gratzl Josef S. , Kirkman Adrianna G. 
Published: October 2004

Summary
The kinetics of delignification of a kraft-AQ southern pine pulp with hydrogen peroxide catalyzed by
[LMn(IV)(μ-O)3Mn(IV)](ClO4)2 (1), where L = 1,2-bis(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)ethane
was studied. The degree of delignification was significantly improved by using the catalyst. The pulp
was bleached for 2 hours at 80°C, in 10% consistency with 2% NaOH, 4% H2O2 and 60 ppm catalyst
charges on pulp (O.D.). Kappa number of the pulp was reduced from 31.6 to 16.8 corresponding to a
degree of delignification of approximately 4%, while GE brightness was increased from 24.2 to 44.7.
At the same time, viscosity of the resulting pulp was reduced from 31.1 mPa•s to 20.1 mPa•s compared
to the reduction from 31.1 mPa•s to 20.1 mPa•s in the uncatalyzed bleaching under the same reaction
condition. This indicates that the degradation of the carbohydrates was moderate in the catalyzed bleaching
compared to the uncatalyzed bleaching. The delignification was found to follow pseudo first order
kinetics with respect to kappa number, i.e., residual lignin, in the initial phase and quickly slowed down
after 30 minutes (residual phase) under all the reaction temperatures investigated. The delignification
rate constants in the initial phase were 0.17, 0.18, and 0.21 min−1 at 50, 60, and 80°C, respectively.
Degree of delignification at the delignification time of 30 minutes is approximately 40% at 80°C. The
possible delignification mechanism was discussed on the basis of the kinetic studies and lignin model
compound experiments.
Monoterpenes in Scots Pine and Norway Spruce and their Emission during Kiln Drying
Authors: Englund Finn , Nussbaum Ralph M. 
Published: October 2004

Summary
Scots pine (Pinus silvestris) and Norway spruce (Picea abies) were dried in a laboratory kiln, using
conventional schedules with temperatures up to 60°C as well as schedules reaching 110°C. The losses
of terpenes, which completely dominate the fugitive emissions from kiln drying of softwoods, were estimated
by extraction of pooled subsamples from each batch, before and after drying. The original contents
of terpenes were found to be in the ranges of 0.4–0.5% in pine sapwood, 0.8–1.1% in pine heartwood,
and 0.02–0.08% in spruce, all calculated relative to the dry weight of the wood. The emissions
from pine corresponded to 25–50% of the original content and those from spruce to 10–50%. High temperature
drying in the laboratory was accompanied by larger losses, but this tendency was not found in
the full-scale drying of spruce. No consistent difference was found between timber from the north of
Sweden and from the south. Sampling of the vent exhaust fumes did not give results of sufficient reliability
to confirm the extraction analyses.
The Dimensional Stabilisation of Maritime Pine Sapwood (Pinus pinaster) by Chemical Reaction with Organosilicon Compounds
Authors: Sèbe Gilles , Jéso Bernard De 
Published: October 2004

Summary
The dimensional stabilisation imparted to Maritime pine sapwood by chemical modification with
hydrophobic organosilicon compounds was investigated. Modification was performed via esterification,
using different chemically synthesised models bearing trimethylsilyl groups: 3-trimethylsilylpropanoic
anhydride (I), 2-trimethylsilylmethylglutaric anhydride (II) and trimethylsilylethenone (III). Grafting
was confirmed by infrared spectroscopy as well as 13C and 29Si NMR CP MAS analysis and was located
into the wood cell walls. The dimensional stabilisation induced by I and II appeared to be stable during
three oven-dry/water-soak cycles and, for a given number of hydroxyl blocked, to be superior to that
imparted by acetylation. The graft from III, however, was found to hydrolyse progressively into an acetyl
group via a metallotropic rearrangement. Further investigation on the hygroscopicity and swelling behaviour
of modified wood from I and II indicated that dimensional stabilisation was attributable to a bulking
effect rather than a change in substrate hygroscopicity. The bulky grafts from I and II were, in particular,
thought to locally over-swell the wood cell wall, revealing regions with new water-accessible
hydroxyl groups.
Comparative Studies of Hemicelluloses Solubilized during the Treatments of Maize Stems with Peroxymonosulfuric Acid, Peroxyformic Acid, Peracetic Acid, and Hydrogen Peroxide. Part 2. Spectroscopic and Thermal Characterizations
Authors: Sun Runcang , Tomkinson J. , Geng Z. C. , Wang N. J. 
Published: October 2004

Summary
Ten hemicellulosic preparations, obtained by treatments of the water-extracted maize stems with peroxymonosulfuric
acid, peroxyformic acid, peracetic acid, and 2% hydrogen peroxide under the conditions
given, respectively, were investigated by gel permeation chromatography and spectroscopic techniques
such as Fourier transform infrared and carbon-13 nuclear magnetic resonance. Under an optimum
extracting condition (2% H2O2, 45°C, 12 h, pH 11.5–12.0), the hemicelluloses obtained represented
63.3–64.7 % of the original hemicelluloses and had high weight-average molar mass between 69060 and
54740 g mol−1. The most obvious feature was found that the alkaline peroxide treatment of the stems
under the conditions used did not affect the overall structure of the hemicelluloses. The thermal stability
of the hemicelluloses was found to increase slightly with increasing molar mass. All the hemicellulosic
preparations were, however, to varying degree thermally unstable at temperature above 180°C.
Hemicellulase Activity of Aerobic Fungal Cellulases
Authors: Lawoko M. , Nutt A. , Henriksson H. , Gellerstedt G. , Henriksson G. 
Published: October 2004

SummaryCellulases isolated fromTrichoderma reeseiandPhanerochaete chrysosporiumwere screened for hemicellulolytic, pectinolytic and cellulolytic activity using locust bean mannan, birchwood xylan, citrus fruit pectin and carboxymethylated cellulose (CMC) as substrates. The purpose of this work was to choose appropriate enzymes to include in a “miniature cellulase system” with minimal hemicellulase activity for the preparation of lignin-carbohydrate complexes (LCCs). The endoglucanases showed CMC activity whereas activity towards the substrate was not detected for the CBHs. Xylanase activity was observed for EG I and EG 38 whereas mannanase activity was observed for EG 44. None of the enzymes degraded pectin. The results suggest that CBH I, CBH II, CBH 58, EG II and EG III are good candidates for the effective preparation of LCCs. The possible biological function for the hemicellulolytic activity of cellulases is discussed.
Molecular Dynamics of Cellulose-Water Systems Investigated by NMR Relaxation Method
Authors: Banas K. , Blicharska B. , Dietrich W. , Kluza M. 
Published: October 2004

Summary
On the basis of the proton NMR relaxation time dependencies on temperature and frequency in cellulose
pulp a simple two-motion model of molecular dynamics has been proposed. The parameters, activation
energies and correlation times, describing the model may be correlated with structure features
such as level of crystallinity of cellulose with different origin, as well as degree of paper devastation.
Predicting the Macromolecular Structure and Properties of Lignin and Comparison with Synthetically Produced Polymers
Authors: Russell Wendy R. , Forrester Alex R. , Chesson Andrew 
Published: October 2004

Summary
Determining the structure of the plant polymer lignin is not feasible because of the heterogeneous structure
of this polymer and the difficulties encountered in its extraction. Therefore, computational chemistry
can provide information, which may otherwise be unavailable. Based on experimental results, computational
chemistry was used to mimic the processes involved in lignin formation. Synthetic polymers
also were prepared from the three major lignin precursors and their physical properties were shown to
give good correlation with computational models constructed to represent these polymers. Both computational
and experimental results, demonstrated that the higher the degree of methoxylation, the more
flexible the polymer and this was shown to be dependent on the type of inter-unit linkage. Using the
same experimentally derived parameters, a model was constructed to represent a generalised lignin. This
model was shown to be a flexible, closely packed structure and this was attributed to the predominance
of 8-O-4 linkages, which allowed closer stacking of the aromatic rings.
Dissociation of Phenolic Groups in Kraft Lignin at Elevated Temperatures
Authors: Norgren Magnus , Lindström Birger 
Published: October 2004

Summary
The dissociation of the phenolic groups in a polydisperse, low molecular weight kraft lignin (Indulin AT)
was studied in alkaline aqueous solutions in the temperature interval 21–70 °C, using a UV-spectrophotometric
method. It was found that at a constant concentration of hydroxide ions, the degree of dissociation
was decreasing when the temperature was elevated. Dissociation curves and apparent pΚ
0 values
were also calculated for the polydisperse sample at the same conditions, using the van't Hoff and the
Poisson-Boltzmann equations. At degrees of dissociation exceeding α ≈ 0.4, the outcome of the theoretical
approach showed to be in good agreement with the experimentally obtained results. Furthermore,
calculations were performed for different molecular weights of kraft lignin and from this it was found
that the apparent pΚ
0 is shifted to higher values by increasing molecular weight, due to an increased electrostatic
attraction of the hydrogen ions, which is arising from a less curved surface.
Predictions of the dissociation behavior at temperatures reached in the kraft process were performed
and under these conditions, higher molecular weight lignin fragments seem never to reach the point of
complete dissociation.
It was also found that an increase in temperature results in phase separation in kraft lignin solutions
with high ionic strengths and pH values close to the pΚ
a of the phenolic groups.
Physico-Chemical Characterization of a Fractionated Kraft Lignin
Authors: Norgren Magnus , Lindström Birger 
Published: October 2004

Summary
A kraft lignin was leached from a softwood pulp and fractionated by ultrafiltration. The fractions were
characterized in respect to phenolic group content, molecular weight distributions and self-diffusion
coefficients. The 1H-Pulsed Field Gradient (PFG) NMR self-diffusion measurements and the High-Pressure
Size Exclusion Chromatography (HPSEC) analysis of the fractions, were seen to correlate fairly
well.
From the self-diffusion measurements, the mass-weighted median hydrodynamic radii of the diffusants
in the fractions, were calculated assuming spherical fragments.
Furthermore, the content of phenolic groups in the fractions, was found to decrease by increasing
hydrodynamic radius and molecular weight, but the calculated median surface charge densities of the
macromolecules, were determined to be constant in the range of oligomers up to at least 65 structural
units.