bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Surface Nano-step Structures and Improvement of Photocatalytic Activities of NaTaO3 by Doping of Alkaline Earth Metal Ions
Authors: Iwase Akihide , Kato Hideki , Okutomi Hiroaki , Kudo Akihiko
Published: September 2004

Powders of NaTaO3 doped with alkaline earth metal ions were prepared. Scanning electron microscopy observation revealed that NaTaO3 crystals doped with Ca, Sr, and Ba became smaller than nondoped NaTaO3 crystals. In addition, nano-step structures were constructed on the surfaces of NaTaO3 doped with Ca, Sr, and Ba. The photocatalytic activity of water splitting on NaTaO3 was improved by the doping of Ca, Sr, and Ba. It is due to the small particle size and the formation of surface nano-step structures as observed for La doping.
Spongiacysteine, a Novel Cysteine Derivative from Marine Sponge Spongia sp.
Authors: Kobayashi Keiko , Shimogawa Hiroki , Sakakura Akira , Teruya Toshiaki , Suenaga Kiyotake , Kigoshi Hideo
Published: September 2004

A novel cysteine derivative, spongiacysteine (1), was isolated from marine sponge Spongia sp. The gross structure was elucidated by detailed spectroscopic analysis, and the absolute stereostructure was established by its total synthesis. This compound showed moderate antimicrobial activity against rice blast fungus Pyricularia oryzae.
Amorphous Molecular Materials with High Carrier Mobilities: Thiophene- and Selenophene-Containing Tris(oligoarylenyl)amines
Authors: Ohishi Hitoshi , Tanaka Masatake , Kageyama Hiroshi , Shirota Yasuhiko
Published: September 2004

A novel class of amorphous molecular materials, thiophene- and selenophene-containing tris(oligoarylenyl)amines, were developed. They were found to exhibit high hole drift mobilities greater than 10−2 cm2V−1s−1 at an electric field of 1.0 × 105 Vcm−1 at 293 K in their amorphous glassy states. These values are of the highest level among those reported for organic disordered systems.
Color Changes Dependent on the Anisotropic Intercalation of Poly(diacetylenecarboxylates) in LDH Clay Hybrids
Authors: Itoh Toshio , Shichi Tetsuya , Yui Tatsuto , Takahashi Hiroki , Takagi Katsuhiko
Published: September 2004

Variation in the coloration of LDH clay-intercalated poly(diacetylenecarboxylates), i.e., poly-[m,n]/LDH, was found to be dependent on the conformations of the carboxylates within the hybrid which were quite sensitive to the carbon numbers, m and n, in the alkyl chains.
One-pot Solution-phase Synthesis of Paramagnetic Co2P Nanorods
Authors: Hou Hongwei , Yang Qing , Tan Chenrong , Ji Guangbin , Gu Benxi , Xie Yi
Published: September 2004

A solution-phase route has been developed for the synthesis of cobalt phosphide nanorods, which have been characterized by techniques of X-ray diffraction (XRD), electron microscope (SEM), and X-ray photoelectron spectroscope (XPS). The microscope analysis reveals that the nanorods have width of about 10 nm and length of 200–300 nm, which exhibit paramagnetic behavior down to 2 K, determined by a commercial superconducting quantum interference device (SQUID) magnetometer.
Palladium-Catalyzed Mizoroki–Heck-type Reactions Using Telluronium Salts
Authors: Hirabayashi Kazunori , Nara Yoshiko , Shimizu Toshio , Kamigata Nobumasa
Published: September 2004

A Mizoroki–Heck-type reaction of telluronium iodides with olefins proceeded under mild conditions to produce substituted olefins in high yields. The reaction required a catalytic amount of palladium(II) species and a stoichiometric amount of silver(I) acetate as an additive.
A Novel Layered Structure of a New Cadmium Chlorophosphate with an Imidazolium Template
Authors: Liu Wei , Chen Hao-Hong , Yang Xin-Xin , Li Man-Rong , Ge Ming-Hui , Zhao Jing-Tai
Published: September 2004

A new organically templated cadmium chlorophosphate, (C3H6N2)[Cd2Cl2(HPO4)2] (C3H6N2 = diprotonated imidazole) with a novel layered structure, was synthesized hydrothermally in the presence of imidazole as a structure-directing agent. This is the first example of a cadmium chlorophosphate with polymeric chains that consist of Cd–O/Cl–Cd units.
Growth of Mesoscale Tubular CdS Crystals via a Hydrothermal Method
Authors: Liu Xinzheng , Guo Fan
Published: September 2004

Cadmium sulfide tubular crystals, with the range of 0.5–2 mm in length, 10–20 μm in the external diameter and 3–6 μm in the wall thickness, were successfully grown in sodium hydroxide solution via a hydrothermal method at 350 °C. XRD, SEM, and XPS methods characterized the products. A possible growth mechanism for the tubular structure was also proposed.
Preparation of Mixed-metal Polynuclear Complexes by Stepwise Phosphine-bridging Reaction
Authors: Aizawa Sen-ichi , Kawamoto Tatsuya , Saito Kenji
Published: September 2004

The phosphine-bridged Pd(II)–Pt(II)–Pd(II) trinuclear and Rh(III)–Pd(II)–Pt(II)–Pd(II)–Rh(III) pentanuclear complexes with tris[2-(diphenylphosphino)ethyl]phosphine (pp3) ligands were successfully prepared by stepwise phosphine-bridging reaction of the terminal phosphino groups of the pp3 ligands on the Pd(II) cores.
Selective Production of ε-Caprolactam via Liquid-phase Beckmann Rearrangement of Cyclohexanone Oxime over HUSY Catalyst
Authors: Ngamcharussrivichai Chawalit , Wu Peng , Tatsumi Takashi
Published: September 2004

ε-Caprolactam was selectively produced through the liquid-phase Beckmann rearrangement of cyclohexanone oxime over HUSY catalyst when the by-products formation was effectively retarded by blockage of the corresponding active centers of pre-adsorbed water and benzonitrile molecules.
A Cross‐national Comparison of R&D Expenditure Decisions: Tax Incentives and Financial Constraints*
Authors: KLASSEN KENNETH J. , PITTMAN JEFFREY A. , REED MARGARET P. , FORTIN STEVE
Published: September 2004

We provide evidence on the impact of tax incentives and financial constraints on corporate R&D expenditure decisions. We contribute to extant research by comparing R&D expenditures in the United States and Canada, thereby exploiting the differences in the two countries' R&D tax credit mechanisms and generally accepted accounting principles. The two tax incentive mechanism designs are consistent with differing views of the degree of financial constraints faced by firms in these economies. Our sample also allows us to explore the effects of capitalizing R&D on Canadian firms. Employing a matched design, we document relations between tax credit incentives and R&D spending consistent with both Canadian and U.S. public companies responding as though they are not financially constrained. We estimate that the Canadian credit system induces, on average, $1.30 of additional R&D spending per dollar of taxes forgone while the U.S. system induces, on average, $2.96 of additional spending. We also find that firms that capitalize R&D costs in Canada spend, on average, 18 percent more on R&D. Collectively, this evidence is important to the ongoing debates in both countries concerning the appropriate design of incentives for R&D and is consistent with the assumptions found in the U.S. tax credit system, but not those found in the Canadian system.
Use of Detergents to Study Membrane Rafts: The Good, the Bad, and the Ugly
Authors: Shogomori H. , Brown D.A.
Published: September 2004

Eukaryotic cell membranes contain microdomains
called lipid rafts, which are cholesterol-rich domains
in which lipid acyl chains are tightly packed and highly
extended. A variety of proteins associate preferentially
with rafts, and this raft association is important
in a wide range of functions. A powerful and widely used
method for studying lipid rafts takes advantage
of their insolubility in non-ionic detergents. Here we
describe the basis of detergent insolubility, and review
strengths, limitations, and unresolved puzzles
regarding this method.
Bioactivatable, Membrane-Permeant Analogs of Cyclic Nucleotides as Biological Tools for Growth Control of C6 Glioma Cells
Authors: Bartsch M. , Zorn-Kruppa M. , Kühl N. , Genieser H.-G. , Schwede F. , Jastorff B.
Published: September 2004

In the present study, the cAMP analogs 8-bromocAMP (8-Brc-AMP), N6-2'O-dibutyryl-cAMP (DBcAMP) and 8-parachlorophenylthio-cAMP (8-CPT-cAMP), as well as the corresponding cAMP-acetoxymethyl (AM)-ester-prodrugs were tested in a HPLC study for their membrane permeability, intracellular accumulation and biotransformation. Antiproliferative activities of these compounds were studied in the rat C6 glioma cell line. Chromatographic analysis revealed that the AM-ester analogs of the cyclic nucleotides penetrate quantitatively into rat C6 glioma cells and generate high amounts of their parent cyclic nucleotides intracellularly within 60 min; however, longterm growth inhibition tested in C6 cells is only slightly enhanced with the AM-ester prodrugs of 8-Br-cAMP or DBcAMP.
HIV TAT Basic Peptide Is Not a High-Affinity Ligand for VEGF Receptor 2
Authors: Demirovic A. Rubio , Canadi J. , Weiglhofer W. , Scheidegger P. , Jaussi R. , Ballmer-Hofer K.
Published: September 2004

The 'transactivator of transcription' (TAT) protein of human immunodeficiency virus transforms cells in culture and promotes the development of tumors, socalled Kaposi's sarcoma, in AIDS patients. TAT induces growth and differentiation of blood vessels and has been suggested to directly activate VEGF receptor 2 expressed on endothelial cells through a peptide sequence located between amino acids 46 and 64, the so-called basic domain. This peptide mimics many aspects of TAT function when added to endothelial cells, even when expressed in the context of recombinant chimeric proteins. To define the exact sites of interaction between this peptide and VEGF receptor 2 we performed binding studies with recombinant proteins derived from the extracellular ligand binding domain of VEGF receptor 2. These in vitro binding studies showed that the TAT peptide binds with only low specificity to Iglike domain 3 of the receptor, while VEGF interacts with receptor-derived proteins encompassing at least extracellular domains 1 through 3. The original concept that the angiogenic properties of TAT basic peptide result from specific, high-affinity interaction with VEGF receptor 2 must therefore be revised. Apparently this peptide interacts with cells in multiple ways: by directly activating acidic cell surface-exposed receptors, by releasing extracellular matrix-bound growth factors such as bFGF and VEGF which then bind to their cognate receptors, and by activating intracellular signalling molecules with which basic peptide interacts upon translocation into cells.
The Relationship Between Variability of Cell Wall Mass of Earlywood and Latewood Tracheids in Larch Tree-Rings, the Rate of Tree-Ring Growth and Climatic Changes
Authors: Silkin P. P. , Kirdyanov A. V.
Published: September 2004

Mass accumulation dynamics in earlywood and latewood cell walls of larch from northern regions
of Central Siberia are investigated and correlations among cell mass of different tree-ring zones,
radial tracheid sizes and tree-ring width are found. A linear relationship exists between cell wall
mass and radial cell size. The deviation of cell mass from the regression line (index of mass deviation)
and the mean density of the respective tree-ring zone are similarly functionally dependent on
the radial cell size and reflect the realization of the potential determined during the period of cell
formation. There is a critical value of larch tree-ring width in relation to cell mass. For the tree-rings
with width less than this critical value the difference in the mass of earlywood and latewood
cells increases with decreasing tree-ring width.The cell wall mass correlates with the monthly temperatures
of June and July. Under favorable growing conditions tracheids with similar mass of cell
walls are formed in earlywood and latewood, while under unfavorable conditions cell wall mass accumulation
in latewood is severly limited. A comparative analysis of the cell wall mass in earlywood
and latewood indicates that mass accumulation is independent of the switching processes
from earlywood production to the production of latewood.
Reactivity of a Fungal Laccase Towards Lignin in Softwood Kraft Pulp
Authors: Lund M. , Eriksson M. , Felby C.
Published: September 2004

The reactivity of a fungal laccase to lignin of six different spruce kraft pulps with kappa numbers ranging from 15 to 110 was studied. Enzymatic oxidation of lignin was investigated by monitoring the oxygen consumption in a suspension of the pulp and the number of radicals generated in the pulp, as measured by electron paramagnetic resonance spectroscopy. The laccase catalyzed oxidation of lignin in kraft pulp followed a double exponential function. This indicates the presence of two types of substrates oxidized by the enzyme at different rates. The two substrates were interpreted as lignin located on the surface of the pulp fibers and as lignin in the cell wall. A linear relationship was found between the kappa number of the pulps and the observed first-order rate constant for oxidation of substrate in the cell wall. Quantification of free radicals in the pulp showed a linear dependence on the lignin content and the number of free radicals generated upon oxidation with laccase.
Investigation of Lignin Oligomers Using Electrospray Ionisation Mass Spectrometry
Authors: önnerud H. , Palmblad M. , Gellerstedt G.
Published: September 2004

Electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (MS) and
size exclusion chromatography (SEC) was utilised for analysis of milled wood lignin (MWL) and
lignin model compounds degraded by thioacidolysis. MS and SEC showed that thioacidolysis was
an efficient method for degradation of the β-O-4 bond in lignin. Moreover, the molecular weight of
thioacidolysed pinoresinol and MWL were analysed using matrix assisted laser desorption ionisation
time-of-flight mass spectrometry. Tandem MS was successfully applied for the structural determination
of thioacidolysed pinoresinol with and without acetylation of the product. The MS results
of thioacidolysis on MWL resulted in the identification of a tetrameric lignin structure
containing a 5-O-4, 5-5, β-1 linkage pattern.
The Reactions of Lignin Model Compounds with Hydrogen Peroxide at Low pH
Authors: Kishimoto T. , Kadla J. F. , Chang H.-m. , Jameel H.
Published: September 2004

In peroxymonosulfuric acid bleaching, the presence of hydrogen peroxide is dependent on the reaction
conditions and the conversion ratios used to generate the peroxy acid. Substantial amounts
of hydrogen peroxide may be present in the reaction system under certain conditions. An understanding
of the reactions of hydrogen peroxide under these conditions would be beneficial. Therefore,
several simple lignin model compounds were reacted with acidic hydrogen peroxide, pH 1-3,
at 70°C. In all cases the phenolic lignin model compounds reacted much faster than their non-phenolic
counterparts. In fact, the extent of reaction was very much dependent on the structure of the
lignin model compound. The α-hydroxyl compounds, 4-(1-Hydroxy-ethyl)-2-methoxy-phenol and
1-(3,4-Dimethoxy-phenyl)-ethanol, reacted faster than the corresponding α-carbonyl compounds
with both reacting much faster than the aromatic compounds, with simple alkyl substituents. A
new reaction mechanism for α-hydroxyl compounds is proposed, in which benzyl carbocation formation
is followed by nucleophilic addition of hydrogen peroxide. Unlike the mechanisms proposed
in the past, no evidence of aromatic hydroxylation via perhydronium ion was observed. The
reactivities were very pH dependent, in that higher reactivity was associated with lower pH. Decreasing
pH further increased the amount of condensation products identified, such that condensation
was competitive with degradation. These condensation reactions were also present under
the Caro's acid bleaching conditions at pH below 2. However, under all conditions the reactivity of
acidic peroxide was found to be much less than that of peroxymonosulfuric acid.
Ultrastructural Localisation of Glucomannan in Kraft Pulp Fibres
Authors: Duchesne I. , Takabe K. , Daniel G.
Published: September 2004

The localisation of glucomannan on the surface of Norway spruce kraft pulp fibres with varying
glucomannan (GM) contents (10.3 and 3.8%) was studied using immunogold labelling, rapid
freeze deep etching (RFDE) followed by metal replication and transmission electron microscopy
(TEM). The ultrastructure of P, S1 and S2 of pulp fibres with low hemicellulose content tended to
be more compact than that of pulp fibres with high hemicellulose content, suggesting aggregation
of cellulose microfibrils upon hemicellulose removal. The degree of immunogold labelling visualised
as globular structures was similar for the two pulps, despite the large difference in total glucomannan
content. Thus, no correlation between the bulk and surface contents of glucomannan
was found. The globular structures were heterogeneously located along the cellulose macrofibrils
(fibril aggregates) and their frequency varied greatly within and between TEM micrographs.
Peroxide Bleaching of Parquet Blocks and Glue Lams
Authors: Möttönen V. , Asikainen A. , Malvaranta P. , Öykkönen M.
Published: September 2004

The lack of a suitable method on an industrial scale has so far restricted the use of bleaching of
solid wood in the woodworking industry. In this study, a new method ‘Wood-Brite™’, based on
bleaching solid wood blocks with hydrogen peroxide solution, was investigated. According to our
measurements, the lightness of all the wood species studied could be increased and the increase
could be controlled by the intensity of peroxide treatment. Differences were observed in the
change of chroma and hue of different wood species. Redness usually decreased regardless of the
treatment intensity, except with teak, in which it increased markedly. At every treatment intensity,
the yellowness of originally light birch wood decreased, but in other wood species it increased.
Easily Degradable Chlorinated Compounds Derived from Glucuronoxylan in Filtrates from Chlorine Dioxide Bleaching of Eucalyptus globulus Kraft Pulp
Authors: Freire C. S. R. , Silvestre A. J. D. , Neto C. Pascoal , Silva A. M. S. , Evtuguin D. V. , Cavaleiro J. A. S.
Published: September 2004

Three mono-chlorinated compounds derived essentially from glucuronoxylan were identified as
the major components of the ethyl acetate extract from chlorine dioxide bleaching filtrates of E.
globulus kraft pulp; one of them is reported for the first time. It was demonstrated that these components
are responsible for an important fraction of the total AOX of the filtrates. The ecological
risk associated with these compounds is expected to be negligible since they are easily degraded
and not detected in the final mill effluent.
Bending Creep of High-Temperature Dried Spruce Timber
Authors: Bengtsson C. , Kliger R.
Published: September 2004

In this paper, bending creep test results from high-temperature (HT) dried Norway Spruce timber
are presented. The results are compared with creep tests of conventional low-temperature (LT)
dried timber. The HT drying was performed at 115°C and the LT drying was performed at 70°C.
The creep tests were performed in a varying climate with 20°C and 30–90% relative humidity. A
total number of 24 specimens, 45 × 70 × 1100 mm, were loaded in bending during approximately
240 days. Both the HT-dried and the LT-dried material were cut from the same four trees to have
as equal raw material as possible for the two drying methods.

The results show smaller bending creep deformations of HT-dried timber (approximately
30%) as compared to the LT-dried timber. The variation in magnitude of creep for HT-dried timber
was equal to or smaller than for LT-dried timber. Additionally, the variation in deformation between
the moisture cycles was smaller for HT-dried timber. These observations indicate a less pronounced
mechano-sorptive effect for HT-dried timber. The free shrinkage in the grain direction
was significantly smaller for the HT-dried material than for the LT-dried material.
Optimisation of Soda Pulping Variables for Preparation of Dissolving Pulps from Oil Palm Fibre
Authors: Rosli W. D. Wan , Leh C. P. , Zainuddin Z. , Tanaka R.
Published: September 2004

A water prehydrolysis-soda pulping sequence for the preparation of dissolving pulps from oil palm
fibre (empty fruit bunches) was investigated using a response surface methodology (RSM) statistical
experiment design. Five response variables of screened yield, Kappa number, α-cellulose, viscosity
and ash content were statistically analyzed with respect to the three input variables of pulping
temperature (T), time-at-temperature (t) and alkali level (A), while keeping the prehydrolysis
conditions constant. Optimum conditions were: T = 161°C, t = 100 min and A= 26.1%. Values predicted
by RSM for screened yield, Kappa number, α-cellulose, viscosity and ash content at the optimum
are 31.2%, 6.0, 96.9%, 16.1 cps and 0.15%, respectively. These values were experimentally
verified and very close agreement between experimental and predicted values was obtained.
Performance of Waterborne Cu(II) Octanoate/Ethanolamine Wood Preservatives
Authors: Humar M. , Pohleven F. , Šentjurc M. , Veber M. , Razpotnik P. , Pogni R. , Petrič M.
Published: September 2004

Various aqueous wood preservative solutions containing Cu(II) in the form of copper(II) sulphate or copper(II) octanoate, ethanolamine and in one case octanoic acid were investigated by spectrophotometry, polarography and Electron Paramagnetic Resonance (EPR) spectroscopy. Results have shown the same coordination environment around Cu(II) in all solutions with ethanolamine. Computer simulation of the EPR spectra also revealed that the coordination in the first coordination sphere of copper is the same at low concentration of ethanolamine. At 20% ethanolamine concentration, a mixture of two complexes (one with two nitrogens and the other with three) could be detected. The active compound in the investigated ethanolamine containing solutions is the same when previously synthesised copper(II) octanoate was used, or when copper(II) sulphate and octanoic acid were utilized instead. Fungicidal and leaching experiments with the treated wood resulted in the same conclusion: it is not necessary to use pre-synthesised copper(II) octanoate for the preparation of waterborne copper/ethanolamine wood preservatives. Preservative preparation time and costs can be reduced by simply dissolving copper(II) sulphate and octanoic acid in aqueous ethanolamine solutions.
Wood Essential Oils of Juniperus foeticissima Willd
Authors: Tunalier Z. , Kirimer N. , Başer K.H.C.
Published: September 2004

Essential oils from heartwood and sapwood of the root and stem of J. foetidissima were analyzed by GC/MS. Cedrol, widdrol, 8,14-cedranoxide, 14-hydroxy-β-caryophyllene, widdrene and α-cedrene were found as main components in the oils. The oil from the root heartwood which was collected as fractions during steam distillation was used for the isolation of constituents. Eight compounds were isolated using chromatographic techniques (such as CC, FC, MPLC, prep HPLC and prep TLC) and characterized by spectral methods as cedrol, widdrol, 8,14-cedrandiol, 8,14-cedranoxide, 14-hydroxy-β-caryophyllene, thujopsenal, α-cedrenal and cadalene.
Cambial Growth of Swietenia macrophylla King Studied under Controlled Conditions by High Resolution Laser Measurements
Authors: Dünisch O. , Schulte M. , Kruse K.
Published: September 2004

The kinetics of phloem and xylem formation of two-year-old plants ofSwietenia macrophyllaKing (true mahogany) was studied in a model system along the shoot circumference (experiment 1) and along the shoot axis (experiment 2). The radius increment of the shoot was registered by high resolution laser measurements (accuracy: ±2 μm) in a spatial resolution of 7.8 to 41.3 μm along the stem circumference and 1.5 mm along the stem axis. The temporal resolution of the measurements was 2 s in experiment 1 and 20 s in experiment 2. The radius increment of the shoot detected by the laser measurements was predominately due to the radial enlargement of the phloem and xylem derivatives. On the phloem side the reinitiation of radial cell enlargement after a cambial dormancy occurred first in sieve tubes with contact to ray parenchyma cells, while on the xylem side the radial cell enlargement of vessels and paratracheal parenchyma was induced almost simultaneously along the shoot circumference. In the phloem and xylem derivatives, which were formed first after the cambial reactivation, radial cell enlargement was induced almost simultaneously along the shoot axis. In more advanced phases of phloem and xylem formation, radial cell enlargement of phloem and xylem derivatives was induced shoot downwards with a rate of approximately 13 mm per min. The mean rate of radial cell enlargement of the phloem and xylem derivatives was 2.26 and 4.37 μm per min, respectively. These findings suggest that the kinetics of cambial growth of tropical tree species differ significantly from kinetics observed in trees from temperate regions. The laser measurements might provide a useful experimental approach for studies of cambial activityin situ.
Inhomogeneities in the Chemical Structure of Hardwood Lignins
Authors: Önnerud H. , Gellerstedt G.
Published: September 2004

Bauer-McNett fractions of an aspen chemi-thermomechanical pulp showed a significant variation
with respect to lignin content and sugar composition, and two of the fractions were found to be
particularly rich in middle lamella and secondary wall material, respectively. The secondary wall
lignin of aspen was found to contain larger amounts of non-condensed β-O-4 aryl ether structures
than the middle lamella lignin and the difference was attributed to a larger amount of syringyl
structures as revealed by thioacidolysis. Size exclusion chromatography of the thioacidolysis products
from birch and spruce wood showed a larger part of lignin oligomers being present in the degraded
spruce lignin. Moreover, birch lignin had a lower phenolic content than both aspen and
spruce lignin. Thioacidolysis followed by Raney-nickel desulphuration was used for the analysis of
hardwood lignin trimers.
Molecular Modeling of Lignin β-O-4 Model Compounds. Comparative Study of the Computed and Experimental Conformational Properties for a Guaiacyl β-O-4 Dimer
Authors: Besombes S. , Robert D. , Utille J.-P. , Taravel F. R. , Mazeau K.
Published: September 2004

The conformational preferences of thethreoanderythrodiastereomeric forms of a guaiacyl β-O-4 dimer have been investigated by molecular modeling using the CHARMM force field. Many low energy conformations have been identified for each diastereomer, showing that β-O-4 dimers can adopt a large variety of shapes. A consistent structural model has emerged that indicates different conformational behavior for thethreoanderythroforms, corresponding to a preferential extended overall shape for thethreoform. All the low energy conformers are stabilized by intramolecular H-bonds. In particular, the highly directional H-bond between the α or γ hydroxyl hydrogen and the aromatic methoxy oxygen governs the B aromatic ring orientation. However, it has appeared that the conformational preferences are predominantly governed by local steric interactions rather than by differences in the H-bonding pattern. From the satisfactory agreement between computed data (geometries and the Boltzmann distribution of the low energy conformers) and the experimental data reported in the literature (X-ray crystal structures and3JHαHβNMR coupling constant), the CHARMM force field has been validated for the study of β-O-4 structures. Clearly, the molecular modeling calculations have led to an improved rationalization of the conformational data collected by experimental techniques.
Kraft Green Liquor Pretreatment of Softwood Chips. Part III: Lignin Chemical Modifications
Authors: Ban W. , Singh J. , Lucia L. A.
Published: September 2004

Quantitative 31P NMR analysis of residual lignin structures isolated from pulps pretreated by
green liquor (GL) as a function of various operating parameters are discussed. Uncondensed phenolics
and condensed hydroxyl groups decreased as the GL charge increased, but increased with
increasing pretreatment temperature. During the cooking of pulps employing variable sulfidities
and the addition of anthraquinone (AQ) or polysulfide (PS), various hydroxyl groups exhibited no
obvious differences in the case of AQ addition, but dramatic changes were observed at variable
sulfidities when the PS was used. The results implied that PS can exert a stronger catalytic effect
under a higher sulfidity and result in more cleavage of the lignin macrostructure. The results also
demonstrated a correlation between the nature of residual lignin and the efficiency of oxygen
delignification based on the finding that the residual lignin in GL modified pulp exhibited a higher
reactivity toward oxygen delignification.
The Role of Ferulic Acid Removal during Bleaching of Wheat Straw Mechanical Pulp with Peroxygen Reagents
Authors: Pan G. X. , Thomson C. I. , Leary G. J.
Published: September 2004

The present paper reports our investigation into the use of two peroxygen reagents, peroxymonosulfate
(PMS) and dimethyldioxirane (DMD), in bleaching sequences with peroxide to bleach
wheat straw mechanical pulp, their reactivity with ferulic acid model compounds, and the likely relation
between the two aspects. It was observed that combinations of PMS or DMD with peroxide
offered a synergy leading to substantially improved brightness development in bleaching of wheat
straw pulp. At the same time, these oxidizing reagents, especially DMD, were shown to be highly
reactive with ferulic acid derivatives and increased the removal of ferulic acid from wheat straw
pulp in bleaching. The results would suggest that the presence of non-lignin, peroxide-resistant
chromophoric components, such as ferulic acid derivatives, might be an important factor limiting
the brightness development of wheat straw mechanical pulp by conventional peroxide bleaching.
Evaluation of the Microclimate in a Stored Softwood Chip Pile for Biopulping
Authors: Wolfaardt F. , Rabie C.
Published: September 2004

Storage of wood chips is preferred to storage of round wood, however, chip deterioration causes
considerable problems in chip piles. Factors contributing to deterioration have, therefore, been
studied to manage chip storage. The requirements of biopulping processes have renewed interest
in the microclimate in these piles. The aim of this study was to assess the suitability of a 3000 ton
softwood chip pile for colonization by a biopulping fungus. This study evaluated conditions such as
temperature, moisture and CO2 that developed over a 3-week period in the chip pile. Zones that
formed within the pile varied in temperature, CO2 concentration and moisture content. The high
temperatures that developed in some areas in the chip pile could make a large volume (29%) of
the chip pile unsuitable for colonization by mesophilic white-rot fungi. The moisture content in
24% of the chip pile reached 55%, but is not expected to have a large impact on biopulping. The
areas of high temperature and high moisture also overlapped. Special management practices
would, therefore, be required to produce a suitable environment in the chip pile for uniform colonization
by biopulping fungi. High levels of CO2 (12.7%) accumulated for a short period in some
areas, but biopulping could still be effective at these levels.
The Relationship between Longitudinal Growth Strain, Tree Form and Tension Wood at the Stem Periphery of Ten- to Eleven-Year-Old Eucalyptus globulus Labill.
Authors: Washusen R. , Ilic J. , Waugh G.
Published: September 2004

The potential for growth strain measurements for detection of tension wood was assessed in trees
from two plantations of 10- to 11-year-old Eucalyptus globulus. Tension wood had commonly developed
at or near the stem periphery of straight, vertical and dominant trees. At a localized level
growth strain was found to be a good indicator of tension wood. However, in some cases moderate
to low growth strain was also detected in some trees where tension wood had been overgrown with
small amounts of normal wood. On a whole tree basis the relationship was not as clear. In this case
growth strain values determined from multiple measurements appear to be influenced primarily
by tissue close to the site of measurements and not by wood at relatively remote locations. In some
cases low growth strain values were found in trees with significant tension wood and in others high
growth strain values where little tension wood had developed.
Topochemical Characterisation of Phenolic Extractives in Discoloured Beechwood (Fagus sylvatica L.)
Authors: Koch G. , Puls J. , Bauch J.
Published: September 2004

The topochemical distribution of phenolic extractives in steamed and kiln-dried beechwood with
discolourations was investigated on a cellular level by using scanning UV microspectrophotometry
(UMSP). For the chemical characterisation of accessory compounds, acetone and methanol
extracts of the discoloured beechwood were separated by accelerated solvent extraction (ASE)
and analysed with high performance liquid chromatography (HPLC). The UV microscopic investigations
reveal that the accessory compounds responsible for the discolouration of beechwood
are mainly restricted to the longitudinal and ray parenchyma cells and the lumen of vessels. The
detected extractives are characterised by high UV absorbance values and an absorbance maximum
in a wavelength range between 280 and 290 nm. The separation of the acetone and methanol
extracts of discoloured beechwood shows the presence of different low molecular phenols such as
catechin and 2,6-dimethoxybenzochinon, which are transformed into high condensation compounds
during steaming and kiln-drying.
Phenolic and Lipophilic Extractives in Scots Pine Knots and Stemwood
Authors: Willför S. , Hemming J. , Reunanen M. , Holmbom B.
Published: September 2004

The phenolic and lipophilic extractives in the heartwood of knots from seven Scots pine trees were
analysed by GC, GC-MS and HPSEC. The knots contained large amounts of phenolic stilbenes,
1–7% (w/w), and lignans, 0.4–3% (w/w), while the stemwood contained around 1% (w/w) of stilbenes
and no detectable lignans. In young trees without stem heartwood the stilbene content in the
knots was up to 200 times that in the stem. Some in-tree and between-tree variation was seen in the
content of phenolic compounds in the knots. The ratio of pinosylvin monomethyl ether to
pinosylvin was higher in the knots than in the stemwood. The most abundant lignan was nortrachelogenin,
but also matairesinol, secoisolariciresinol and liovil were present in small amounts in the
knots. The knots also contained a complex mixture of lignan-like compounds, here called oligolignans.
The flavonoid pinocembrin was present in both stemwood and knots in amounts below
0.02% (w/w). The stilbene concentration in the radial direction, from the pith to the outer branch,
decreased or was on the same level inside the stem, while it decreased markedly in the outer
branch. The lignan concentration was on the same level or decreased slightly inside the stem, while
it decreased markedly in the branches and became almost non-existent within 10 cm out in the
branches. The knots contained large amounts (4.5–32% (w/w)) of lipophilic extractives, mainly
resin acids. Some in-tree and between-tree variation was seen for the resin acids. The abietane-type
resin acids dominated over the pimarane-type acids and abietic acid was the most abundant
resin acid in the knots and in stem heartwood. The amount of resin acids in the radial direction decreased
or was on the same level inside the stem, while a clear decrease was detected in the branches.
The profile of the distribution of resin acids and phenolic compounds was similar. The knots
also contained up to 0.5% (w/w) of diterpenyl aldehydes.
Measuring Relative Fibre Length in Scots Pine by Non-Destructive Wood Sampling
Authors: Fries A. , Ericsson T. , Mörling T.
Published: September 2004

Wood fibre length of Scots pine (Pinus sylvestrisL.) was measured in wood sticks and 5-mm increment cores. The aim was to evaluate whether fibre length estimates from such small-diameter cores could be used to calculate genetic parameters, in spite of the increased amount of cut fibres produced at boring. The correlation between mean fibre lengths obtained from cores and sticks, with substantially fewer cut fibres, was high (r= 0.87,n= 53) and of the same magnitude as the correlation between samples from varied positions in the same tree (r= 0.87,n= 46). As regards evaluation of genetic tests and ranking for selection purposes, values from non-destructively sampled 5-mm cores from 0.5 m tree height appear to serve well. Fibre length development along annual ring classes started to differentiate between trees at annual rings 13–15, and after ring 16 there was a slight tendency towards stabilisation which may be interpreted as a reasonably advanced transition from juvenile wood to mature wood.
Modelling Log-End Cracks Due to Growth Stresses: Calculation of the Elastic Energy Release Rate
Authors: Jullien D. , Laghdir A. , Gril J.
Published: September 2004

The occurrence of log-end cracks, due to the release of growth stress pre-existing in the standing
tree, causes severe damage at the early stage of wood transformation. A mechanical model based
on Griffith's theory for elastic-fragile materials has been developed to explain the observed patterns:
a crack can only progress when the elastic energy release rate (G) exceeds the toughness
(Gc) of the material for the given fracture mode and orientation. At each stage of the crack propagation,
G was calculated using the finite-element method. The influence of various parameters related
to the rigidity components, the initial growth stress field or the crack geometry has been investigated,
based on a set of experimental data gathered on a population of Eucalyptus. In all cases
the high G values just after crack initiation are followed by a marked decrease until the periphery
has been reached. Their order of magnitude for a typical log is similar to Gc values measured independently
on similar material, thus supporting the validity of the approach.
A Theoretical Analysis of Timber Drying in Oscillating Climates
Authors: Salin J.-G.
Published: September 2004

In this study the influence of oscillating climates on the drying of timber is investigated theoretically.
First, the effect of oscillations superimposed on an ordinary drying schedule is examined by
solving the corresponding partial differential equations. It is shown that the average drying rate is
not affected by the oscillations. Second, properly selected oscillation amplitudes and frequencies
can result in enhanced mechano-sorptive creep in the board surface layer, which enables increased
external driving forces with an unchanged risk of checking. This method is analysed by using a drying
simulation model. It is shown that substantial reductions in the drying time can be obtained in
theory. From a practical point of view the benefit is probably rather marginal.
Wood-Derived Porous Ceramics via Infiltration of SiO2-Sol and Carbothermal Reduction
Authors: Klingner R. , Sell J. , Zimmermann T. , Herzog A. , Vogt U. , Graule T. , Thurner P. , Beckmann F. , Müller B.
Published: September 2004

The use of wood as a structure-giving material may be the key to producing temperature-resistant
ceramics featuring high and directed porosity combined with necessary strength. The objective of
this study was to develop a simple process to convert the evolutionarily optimized material wood
into highly porous ceramics. Beech and pine, known to be relatively permeable, were pyrolyzed in
a nitrogen atmosphere. The carbon-templates formed were infiltrated with various kinds of silica
sol (SiO2). The resulting SiO2/C composite was transformed into a SiC-ceramic (silicon carbide)
via carbothermal reduction. Through the described process the macroscopic pore-structure of
wood was transformed exactly into SiC. The SiC-ceramic produced proved to be thermo-resistant.
It remained stable in oxygen atmosphere at 1200°C, after a SiO2 coating around the SiC had been
formed. This study focused on the alteration of the cell wall microstructure during the conversion
of wood into SiC. Furthermore, the optimization of the individual process steps, pyrolysis, infiltration
and ceramization along the most efficient route was pursued.
Manufacture of Fiberboard from Wood Fibers Activated with Fentons Reagent (H2O2/FeSO4)
Authors: Widsten P. , Qvintus-Leino P. , Tuominen S. , Laine J. E.
Published: September 2004

Fiberboard was manufactured without synthetic resins from spruce and beech fibers activated by
treatment with Fenton's reagent (H2O2/FeSO4) and the formation of radicals in the fibers by the
action of Fenton's reagent was studied. The treatment resulted in a strong improvement of board
strength and a large increase in fiber free radical content. The improved adhesion is probably
largely due to interfiber bonds formed by reactions of radicals or other reactive groups generated
in the fibers by Fenton's reagent. The reactivity of spruce fibers in terms of radical formation increased
as defibration temperature increased. The thickness swell of the boards depended more
on the amount of sizing agent or other additive than on the defibration temperature or fiber reactivity
toward Fenton's reagent.
Formation of β-O-4 Lignin Models -A Theoretical Study
Authors: Durbeej B. , Eriksson L. A.
Published: September 2004

The formation of two different β-O-4 lignin models is investigated by means of density functional
calculations. It is found that the coupling of two coniferyl alcohol radicals forming a quinone methide
proceeds by an energy barrier of ~2–5 kcal/mol, and that the associated reaction energy is
negative by more than 20 kcal/mol. On the basis of the corresponding results obtained for the coupling
of a coniferyl alcohol radical to a coniferyl alcohol, it is argued that the resulting radical, albeit
being formed in an energetically less favourable process, might play an important role in lignin
polymerisation. Finally, two different reaction mechanisms for the conversion of a quinone methide
into a guaiacylglycerol-β-coniferyl ether dilignol through the addition of water are explored.
Alkaline Chemi-Mechanical Pulp from Poplar. Relationship between Chemical State, Swelling and Papermaking Properties
Authors: Zanuttini M. , Marzocchi V.
Published: September 2004

In order to analyse the fundamentals of alkaline chemi-mechanical pulping of hardwoods, the
chemical state of the wood was related to both the swelling level of fibres and the papermaking
properties of pulp. Wafers of poplar wood were alkali treated following a factorial experimental
design for two variables: temperature and alkali concentration. Treated wafers were hot defibrated
in a 300-mm disk mill at 15% consistency, and then refined in PFI mill at 20% consistency. Results
show how fibre swelling gradually increases as alkaline action is increased. The significant improvement
in tensile and tear strength of the pulp can, in great part, be ascribed to the development
of fibre bonding capacity. A limited effect of ion content on cell wall swelling was found.
Swelling correlates well with deacetylation level, and is a major factor in determining the tensile
strength and scattering ability of the pulp.
Analysis of Pinus radiata D. Don Bark by Near Infrared Spectroscopy
Authors: Schimleck L. R. , Yazaki Y.
Published: September 2004

The estimation of a range of Pinus radiata D. Don bark properties by calibrated near infrared
(NIR) spectroscopy is reported. A series of P. radiata samples were characterised in terms of hot
water extractives, NaOH extractives and Stiasny value. NIR spectra were obtained from the milled
bark of each sample and used to develop calibrations for each parameter. Coefficients of determination
(R2) ranged from 0.84 (NaOH extractives) to 0.94 (Stiasny value). Standard errors of calibration
ranged from 0.96 (NaOH extractives) to 2.47 (Stiasny value). When applied to a separate
test set, the hot water extractives and Stiasny value calibrations performed well, while the NaOH
calibration was disappointing. The calibration developed for Stiasny value could be of considerable
practical importance as the method used to determine Stiasny value is particularly time consuming.
Effect of High Temperature on the Change in Color, Dimensional Stability and Mechanical Properties of Spruce Wood
Authors: Bekhta P. , Niemz P.
Published: September 2004

In this study the effect of high temperature on mechanical properties, dimensional stability and
color of spruce was investigated. Wood specimens conditioned at different relative humidities (50,
65, 80 and 95%) were subjected to heat treatment at 200°C for 2, 4, 8, 10 and 24 h and at 100, 150
and 200°C for 24 h. Color changes were measured in the Minolta Croma-Meter CR-300 color system.
Bending strength and modulus of elasticity were determined according to DIN 52186. The results
show that heat treatment mainly resulted in a darkening of wood tissues, improvement of the
dimensional stability of wood and reduction of its mechanical properties. The darkening accelerated
generally when treatment temperature exceeded approximately 200°C. Most of the darkening
occurred within the first 4 h of exposure. For the specimens heated to high temperatures, the average
decrease in bending strength was about 44–50%, while modulus of elasticity was reduced by
only 4–9%. We found that treatment time and temperature were more important than relative humidity
regarding the color responses. Strong correlations between total color difference and both
modulus of elasticity and bending strength were found. Thus, the color parameters can be estimated
quantitatively and used as a prediction of wood strength.
Effects of Clonal Selection by Microfibril Angle on the Genetic Improvement of Stiffness in Cryptomeria japonica D. Don
Authors: Nakada R. , Fujisawa Y. , Hirakawa Y.
Published: September 2004

The microfibril angle (MFA) of latewood tracheids and its radial variation at breast height in
Cryptomeria japonica D. Don (sugi) were investigated with twelve clones collected from three
sites in the Kyushu region, Japan. Large variations both between clones and between sites were observed.
The MFAs were well correlated to the stiffness of the logs collected from the sample trees.
A simulation of clonal selection according to the ranking of the clones in MFA demonstrated that
the log stiffness of the selected population was much improved even when the selection relied on
MFAs in the second ring from the pith. The improvement in log stiffness by MFA selection was not
different from the selection by log stiffness itself. The results indicate that early selection by MFA
is very effective in improving log stiffness in this species.
Loss of Flight and Associated Neuronal Rhythmicity in Inositol 1,4,5-Trisphosphate Receptor Mutants ofDrosophila
Authors: Banerjee Santanu , Lee Jisue , Venkatesh K. , Wu Chun-Fang , Hasan Gaiti
Published: September 2004

Coordinated flight in winged insects requires rhythmic activity of the underlying neural circuit. Here, we show thatDrosophilamutants for the inositol 1,4,5-trisphosphate (InsP3) receptor gene (itpr) are flightless. Electrophysiological recordings from thoracic indirect flight muscles show increased spontaneous firing accompanied by a loss of rhythmic flight activity patterns normally generated in response to a gentle puff of air. In contrast, climbing speed, the jump response, and electrical properties of the giant fiber pathway are normal, indicating that general motor coordination and neuronal excitability are much less sensitive toitprmutations. All mutant phenotypes are rescued by expression of anitpr+transgene in serotonin and dopamine neurons. Pharmacological and immunohistochemical experiments support the idea that the InsP3receptor functions to modulate flight specifically through serotonergic interneurons. InsP3receptor action appears to be important for normal development of the flight circuit and its central pattern generator.