bluuebunny/crossref_metadata_2025 huggingface dataset:
Delocalization of Positive and Negative Charge Carriers on Oligo- and Poly-fluorenes Studied by Low-Temperature Matrix Isolation Technique
Authors: Koizumi Yoshiko , Seki Shu , Acharya Anjali , Saeki Akinori , Tagawa Seiichi
Published: September 2004

Oligofluorenes with well-defined chain length (n = 1–5) have been synthesized by step-by-step Suzuki coupling reaction as the basis sets of conjugated segments in polyfluorenes. Cation and anion radicals of oligofluorenes (n > 2) showed intense and clear three infrared absorptions attributed to transitions between SOMO state delocalized over fluorene moieties and valence (HOMOs) or conduction states (LUMOs) in the backbone. The transition energies of the IR band decreased linearly from 1.2 to 0.55 eV in the range of unit number while 1-D exciton transition energies showed apparent saturation at n > 5. This implied that delocalization degree of excess electrons or holes along fluorene chains would saturate at larger number of units than that of neutral excitons.
Sexually Transmitted Diseases Among American Youth: Incidence and Prevalence Estimates, 2000
Authors: Weinstock Hillard , Berman Stuart , Cates Willard
Published: September 2004

CONTEXT In the United States, young people aged 15–24 represent 25% of the sexually experienced population. However, the incidence and prevalence of sexually transmitted diseases (STDs) among this age‐group are unknown.

METHODS Data from a variety of sources were used to estimate the incidence and prevalence of STDs among 15–24‐year‐olds in the United States in 2000. The quality and reliability of the estimates were categorized as good, fair or poor, depending on the quality of the data source.

RESULTS Approximately 18.9 million new cases of STD occurred in 2000, of which 9.1 million (48%) were among persons aged 15–24. Three STDs (human papillomavirus, trichomoniasis and chlamydia) accounted for 88% of all new cases of STD among 15–24‐year‐olds.

CONCLUSIONS These estimates emphasize the toll that STDs have on American youth. More representative data are needed to help monitor efforts at lowering the burden of these infections.
The Estimated Direct Medical Cost of Sexually Transmitted Diseases Among American Youth, 2000
Authors: Chesson Harrell W. , Blandford John M. , Gift Thomas L. , Tao Guoyu , Irwin Kathleen L.
Published: September 2004

CONTEXT: Each year, millions of U.S. youth acquire sexually transmitted diseases (STDs). Estimates of the economic burden of STDs can help to quantify the impact of STDs on the nation's youth and on the payers of the cost of their medical care.

METHODS: We synthesized the existing literature on STD costs to estimate the lifetime medical cost per case of eight major STDs–HIV, human papillomavirus (HPV), genital herpes simplex virus type 2, hepatitis B, chlamydia, gonorrhea, trichomoniasis and syphilis. We then estimated the total burden of disease by multiplying these cost‐per‐case estimates by the approximate number of new cases of STDs acquired by youth aged 15–24.

RESULTS: The total estimated burden of the nine million new cases of these STDs that occurred among 15–24‐yearolds in 2000 was $6.5 billion (in year 2000 dollars). Viral STDs accounted for 94% of the total burden ($6.2 billion), and nonviral STDs accounted for 6% of the total burden ($0.4 billion). HIV and HPV were by far the most costly STDs in terms of total estimated direct medical costs, accounting for 90% of the total burden ($5.9 billion).

CONCLUSIONS: The large number of infections acquired by persons aged 15–24 and the high cost per case of viral STDs, particularly HIV, create a substantial economic burden.
Adolescent Clinic Visits for Contraception: Support from Mothers, Male Partners and Friends
Authors: Harper Cynthia , Callegari Lisa , Raine Tina , Blum Maya , Darney Philip
Published: September 2004

CONTEXT: To increase effective contraceptive use among adolescents at high risk of pregnancy, it is important to understand what factors influence them to visit a clinic for contraception, including support from their mothers, male partners and friends.

METHODS: Data from a prospective cohort study of 399 teenage clinic attendees using the pill, the implant or condoms were collected through a questionnaire at baseline and at a one‐year follow‐up interview. Data were analyzed using multivariate regression analysis to show differences in social support for adolescents' clinic visit at baseline and method continuation at one year.

RESULTS: Almost all teenagers (96%) reported that their mother, a male partner or a friend was aware of their clinic visit for contraception; of these, 92–96% also said that their mother or a male partner was supportive. Teenagers who chose the pill or implant were more likely than condom users to report that their mother and male partner were aware and that their mother was supportive of their contraceptive clinic visit. Implant users were significantly more likely than those who chose the pill or condom to continue using their chosen method for one year. Teenagers who took part in high‐risk behaviors were more likely than others to involve a friend but not their mother or a male partner in their contraceptive decision‐making.

CONCLUSIONS: Pregnancy prevention programs and counseling protocols that integrate supportive networks for teenagers into contraceptive services may help adolescents to use effective methods.
Market Structure and Audit Fees: A Local Analysis*
Authors: BANDYOPADHYAY SATI P. , KAO JENNIFER L.
Published: September 2004

This study conducts a local analysis of the relation between market structure and audit fees. The research question of interest to us is how audit fees are determined by each practicing local office, after taking into account the auditor's own position in a local market and the influence exerted by his or her clients. Appealing to the economic theories of monopoly and monopsony power, we hypothesize a positive audit fee‐concentration relation, and a negative audit fee‐client influence relation. Results indicate that auditor market concentration is positively associated with the non‐Big 6 audit fees but is unrelated to the Big 6 audit fees. Evidence is mixed concerning the client influence hypothesis. When this construct is proxied by the number of rival auditors operating within a geographic area centered on the municipality, the prediction of negative audit fee‐client influence relation is strongly supported for both groups of auditors. Results are much weaker using measures developed based on the relative importance of a municipal client to its auditor's audit portfolio. The issues addressed in this study are important at a time when the Canadian municipal sector is undergoing major changes because of municipal amalgamation, altering the underlying market structure for audit services and the bargaining position of a municipality vis‐Ã‐vis its auditor. More broadly speaking, our analysis implies that when assessing an auditor's report for signs of client pressure, the professional oversight bodies and regulatory authorities need to consider the relative, rather than the absolute, bargaining position of the client in question.
Equilibrium Earnings Management, Incentive Contracts, and Accounting Standards*
Authors: LIANG PIERRE JINGHONG
Published: September 2004

In this paper, we model earnings management as a consequence of the interaction among self‐interested economic agents ‐ namely, the managers, the shareholders, and the regulators. In our model, a manager controls a stochastic production technology and makes periodic accounting reports about his or her performance; an owner chooses a compensation contract to induce desirable managerial inputs and reporting choices by the manager; and a regulatory body selects and enforces accounting standards to achieve certain social objectives. We show that various economic trade‐offs give rise to endogenous earnings management. Specifically, the owner may reduce agency costs by designing a compensation contract that tolerates some earnings management because such a contract allocates the compensation risk more efficiently. The earnings‐management activity produces accounting reports that deviate from those prescribed by accounting standards. Given such reports, the valuation of the firm may be nonlinear and s‐shaped, thereby recognizing the manager's reporting incentives. We also explore policy implications, noting that (1) the regulator may find enforcing a zero‐tolerance policy ‐ no earnings management allowed ‐ economically undesirable; and (2) when selecting the optimal accounting standard, valuation concerns may conflict with stewardship concerns. We conclude that earnings management is better understood in a strategic context that involves various economic trade‐offs.
Professionalization in Action: Accountants' Attempt at Building a Network of Support for the WebTrust Seal of Assurance*
Authors: GENDRON YVES , BARRETT MICHAEL
Published: September 2004

This paper examines the attempts by the North American accounting institutes to develop a new market in e‐commerce assurance based on their claims to professional expertise through the WebTrust project. Employing actor‐network theory in an in‐depth longitudinal field study, we investigate how WebTrust was originally developed and promoted as a seal of business‐to‐consumer assurance, which largely failed to generate support in the marketplace. Proponents were subsequently able to generate more interest in the eyes of managers of online organizations by reshaping WebTrust as a flexible set of principles and criteria for systems advice and business‐to‐business assurance. Our analysis suggests that attempts to expand the accounting profession's domain of expertise reflect a trial‐and‐error process where the outcome achieved may be far from the vision that motivated the institutes into undertaking the project in the first place. We further show that the initial network of support for such projects can be quite fragile and dynamic as various actors reposition themselves around the shifting meanings attributed to the project.
Decomposition of Fraud‐Risk Assessments and Auditors' Sensitivity to Fraud Cues*
Authors: WILKS T. JEFFREY , ZIMBELMAN MARK F.
Published: September 2004

Practitioners and regulators are concerned that when auditors perceive management's attitude or character as indicative of low fraud risk, they are not sufficiently sensitive to high levels of incentive or opportunity risks in their overall fraud‐risk assessments. In this study, we examine whether a fraud‐triangle decomposition of fraud‐risk assessments (that is, separately assessing attitude, opportunity, and incentive risks prior to assessing overall fraud risk) increases auditors' sensitivity to opportunity and incentive cues when perceptions of management's attitude suggest low fraud risk. In an experiment with 52 practicing audit managers, we find that auditors who decompose fraud‐risk assessments are more sensitive to opportunity and incentive cues when making their overall assessments than auditors who simply make an overall fraud‐risk assessment. However, this increased sensitivity to opportunity and incentive cues appears to happen only when those cues suggest low fraud risk. When opportunity and incentive cues suggest high fraud risk, auditors are equally sensitive to those cues whether they use a decomposition or a holistic approach. We discuss and examine potential explanations for this finding.
JIT Adoption: The Effects of LIFO Reserves and Financial Reporting and Tax Incentives*
Authors: KINNEY MICHAEL R. , WEMPE WILLIAM F.
Published: September 2004

Using matched samples of JIT adopters and nonadopters, we examine the association of JIT adoption with firms' financial reporting and tax incentives, earnings‐management histories, and LIFO reserve levels. We find evidence that adoption decisions are influenced by the interaction of firms' LIFO reserves with their income smoothing, debt covenant, and tax incentives. We also find that adoption is less likely for firms historically engaging in high degrees of earnings management, particularly when such firms have no substantial LIFO reserves. Our study extends earlier research demonstrating a relation between inventory valuation method and year‐end inventory transactions, and documents a relation between earnings‐management incentives and a fundamental supply‐chain design choice.
A Nucleosome-Free dG-dC-Rich Sequence Element Promotes Constitutive Transcription of the Essential Yeast RIO1 Gene
Authors: Angermayr M. , Schwerdtfeger K. , Bandlow W.
Published: September 2004

RIO1 is an essential gene that encodes a protein serine kinase and is transcribed constitutively at a very low level. Transcriptional activation of RIO1 dispenses with a canonical TATA box as well as with classical transactivators or specific DNA-binding factors. Instead, a dG-dC-rich sequence element, that is located 40 to 48 bp upstream the single site of mRNA initiation, is essential and presumably constitutes the basal promoter. In addition, we demonstrate here that this promoter element comprises a nucleosomefree gap which is centered at the dG-dC tract and flanked by two positioned nucleosomes. This element is both, necessary and sufficient, for basal transcription initiation at the RIO1 promoter and, thus, constitutes a novel type of core promoter element.
Molecular Recognition between Azotobacter vinelandii Rhodanese and a Sulfur Acceptor Protein
Authors: Cereda A. , Forlani F. , Iametti S. , Bernhardt R. , Ferranti P. , Picariello G. , Pagani S. , Bonomi F.
Published: September 2004

The occurrence of rhodanese-like proteins in the major
evolutionary phyla, together with the observed
abundance of these proteins also within the same
genome, suggests that their function cannot be limited
to cyanide scavenging. The aim of the present
study was to investigate whether Azotobacter vinelandii
RhdA, an enzyme possessing unique biochemical
and structural features with respect to other
members of rhodanese homology superfamily, could
recognize a suitable protein as a potential acceptor of
the sulfane sulfur held on its catalytic Cys residue.
Both the potential sulfur-delivery RhdA-S and the sulfur-
deprived RhdA were found to interact with either
holo- or apo-adrenodoxin, the 'substrate' protein
used in this work. Interaction of RhdA-S with apoadrenodoxin
led to mobilization of RhdA-S sulfane
sulfur. Under appropriate conditions, the sulfur released
from RhdA-S was productively used for 2Fe
2S cluster reconstitution to yield holo-adrenodoxin
from apo-adrenodoxin in the absence of any other
sulfur source. A comparison of the reactivity of RhdA-S
with protein and non-protein thiols allowed also
some insights into the accessibility of the sulfane sulfur
carried by RhdA.
Modulation of the Activation of Extracellular Signal-Regulated Kinase (ERK) and the Production of Inflammatory Mediators by ADP-Ribosylation Inhibitors
Authors: Page C. Le , Wietzerbin J.
Published: September 2004

ADP-ribosylation is involved in nuclear factor κB (NF-κB)-dependent gene expression induced by lipopolysaccharide in murine macrophages. Here we have investigated the mechanism by which ADP-ribosylation inhibitors block signaling pathways induced in macrophages. In RAW264.7 macrophages the inducers of NF-κB activate the production of reactive oxygen species and three mitogenactivated protein kinases (MAPK), the extracellular signal regulated kinase (ERK), the c-jun N-terminal kinase/stress-activated protein kinase (JNK), and p38. We demonstrate that ADP-ribosylation inhibitors specifically inhibit ERK MAPK activation and reduce the release of inflammatory mediators such as tumor necrosis factor α (TNF-α), IL-6 and nitrite.
Aza-Peptide Epoxides: Potent and Selective Inhibitors of Schistosoma mansoni and Pig Kidney Legumains (Asparaginyl Endopeptidases)
Authors: James K. E. , Götz M. G. , Caffrey C. R. , Hansell E. , Carter W. , Barrett A. J. , McKerrow J. H. , Powers J. C.
Published: September 2004

Aza-peptide epoxides are a new class of irreversible
cysteine protease inhibitors. Derivatives containing a
P1 aza-asparagine residue are specific for Schistosoma
mansoni and pig kidney legumains, which are clan
CD cysteine proteases. The inhibitors have secondorder
rate constants of up to 104 M-1s -1 with pig kidney
legumain and IC50 values as low as 45 nM with S.
mansoni legumain. The most potent epoxides contain
an ester moiety with S,S stereochemistry attached to
the epoxide. Interestingly, amide and amino acid derivatives
of the epoxysuccinate moiety were not inhibitors
of legumain, while disubstituted amide derivatives
are quite potent. The inhibitors have little or no
inhibitory activity with other proteases such as caspases,
chymotrypsin, papain, cathepsin B, granzyme
B, and various aspartyl proteases.
How Variability in OSB Mechanical Properties Affects Biological Durability Testing
Authors: Curling S. F. , Winandy J. E. , Carll C. , Micales J. A. , A. Tenwolde A.
Published: September 2004

Loss in bending strength of wood has been shown to be a more sensitive measure of decay than is
weight loss. Using modulus of rupture as the decay criterion is problematic for oriented strandboard
(OSB) because of variation in mechanical properties due to particle orientation and size.
Moreover, the small specimen size required for such tests increases the variance in mechanical
properties. This study compared the variance in bending strength of ASTM D1037 standard-sized
specimens and small specimens from two samples of commercial OSB. The small specimens were
found to have a significantly higher level of variance in bending strength than the standard-sized
specimens. A simple method of sorting the specimens based on strand orientation on the tensile
surface significantly reduced the level of variance measured. The effects of differing levels of variance
on the size, design and limitations of the experimental study are presented.
Microfibril Angles Inside and Outside Crossfields of Norway Spruce Tracheids
Authors: Lichtenegger H. C. , Müller M. , Wimmer R. , Fratzl P.
Published: September 2004

The major part of the wood cell wall consists of parallel-aligned cellulose fibrils. Locally, pits connecting
adjacent cell walls disturb the fibril arrangement. The local fibril orientation around these
mechanically weak points is crucial for the mechanical stability of the cell. In some softwood
species like spruce, the pit apertures at junctions of tracheids and cross-running ray parenchyma
cells are elongated and slit-like. The pit orientation has often been assumed to directly reflect the
fibril orientation. In this paper we use X-ray microdiffraction to determine the local microfibril angle
(tilt angle versus the cell axis, MFA) in single tracheid walls of Norway spruce in the vicinity of
pit apertures. The results from microdiffraction are compared with the pit orientation observed
under the light microscope.Whereas a good correlation was found in thick-walled latewood cells
from the stem and compression wood, large discrepancies occurred for thin-walled earlywood
cells. A simple mechanical model that could explain the different situation in earlywood and latewood
is presented.
Lignans and Lipophilic Extractives in Norway Spruce Knots and Stemwood
Authors: Willför S. , Hemming J. , Reunanen M. , Eckerman C. , Holmbom B.
Published: September 2004

The hydrophilic and lipophilic extractives in the heartwood of knots from 7 Norway spruce trees
were analysed by GC, GC-MS and HPSEC. The knots contained extremely large amounts of lignans,
6–24% (w/w), with hydroxymatairesinol comprising 65–85% of the lignans. Even the knots
of the young trees contained 4–8% (w/w) of lignans. The variation in the amount of lignans was
large among knots, both within a single tree and between trees. In addition to the lignans, knots
also contained 2–6% (w/w) of a complex mixture of lignan-like compounds with 3, 4 and even up
to 6 phenyl propane units, here called oligolignans. The amounts of lignans in the knots were similar
in the radial direction from the pith into the outer branch, but decreased dramatically outwards
in the branch, almost disappearing after 10–20 cm. The ratio of the 2 epimers of hydroxymatairesinol
differed between different knots and even within the knot. A new spruce lignan, nortrachelogenin,
or its enantiomer, wikstromol, was detected in knots from trees in northern Finland
as opposed to samples from southern Finland. The amount of lipophilic extractives was small compared
to the amount of hydrophilic extractives in the knots. Five of the dead knots contained more
resin acids and free diterpenyl alcohols than ordinary stemwood. In the other knots, the amount of
lipophilic extractives was on the same level as stem heartwood. The stem sapwood contained larger
amounts of esterified fatty acids than the knots.
Reactions of Lignin with Peroxymonophosphoric Acid: The Degradation of Lignin Model Compounds
Authors: Zhu T. , Kadla J. F. , Chang H.-m. , Jameel H.
Published: September 2004

Peroxymonophosphoric acid (Pp) has been shown to be an excellent delignification chemical for
kraft pulps. However, the reaction mechanism of Pp with lignin has not been elucidated. Therefore,
the reactions of Pp with non-phenolic lignin model compounds have been investigated at 70
and 90°C and compared to those of peroxymonosulfuric acid (Px). Pp and Px appear to follow
similar reaction pathways, however, the reaction kinetics are significantly different. Both Pp and
Px react with 1,2-Dimethoxy-4-methyl-benzene as electrophiles, with aromatic hydroxylation being
the main initial reaction. For 1-(3,4-Dimethoxy-phenyl)-ethanone, both Px and Pp react via the
Baeyer-Villiger reaction, in which the initial step is nucleophilic attack by the peracid.The reaction
with 1-(3,4-Dimethoxy-phenyl)-ethanol occurs primarily via carbocation formation followed by
subsequent reactions with the peracid. Changes in pH dramatically affect the reaction rates of Pp
with all the model compounds investigated, whereas with the exception of the Baeyer-Villiger reaction,
changes in pH did not affect the Px reactions. Below pH 2, Pp is a better electrophile than
Px, but above pH 2, Px is better. In addition, while Px remains reactive, Pp is not reactive at pH
above 7 for the model compounds investigated.
New Method for Quantitative Preparation of Lignin- Carbohydrate Complex from Unbleached Softwood Kraft Pulp: Lignin-Polysaccharide Networks I
Authors: Lawoko M. , Henriksson G. , Gellerstedt G.
Published: September 2004

A new method for the quantitative preparation of pulp representative lignin-carbohydrate complexes
(LCC) has been developed, in which LCC has been systematically prepared at quantitative
yield, fractionated and qualitatively determined. At least 90% of residual lignin in softwood kraft
pulp is proposed to be chemically bonded to carbohydrates. A major part of LCC (92%) in softwood
kraft pulp was observed between lignin, xylan and glucomannan, whereas a minor part (8%)
was linked to cellulose. Half of the hemicelullosic LCC is a lignin-glucomannan complex. The other
half is lignin-xylan complex and xylan-lignin-glucomannan complex. Thus, part of the residual
lignin in softwood kraft pulp crosslinks xylan and glucomannan. The proposed linkages are of covalent
type. At most 10% of the residual lignin is not bonded covalently to carbohydrates.
Non-Deterministic Description of Wood Radio Frequency Vacuum Drying
Authors: Elustondo D. , Koumoutsakos A. , Avramidis S.
Published: September 2004

A numerical method is proposed to predict the stochastic dispersion of data that unavoidably occurs
in a real drying process. The method is based on the use of discrete frequency distribution
curves to predict a random variation on some parameters of the process and is applied to the case
of radio frequency vacuum (RFV) drying of wood. Experimental data of RFV drying of western
hemlock timbers were used to obtain the numeric values of the stochastic parameters and their
standard deviation. A mathematical model was designed to simulate the final moisture content
dispersion on hypothetical examples. Results were quantified using three indices: average, range
and standard deviation.
Molecular Identity of Species and Isolates of Internal Pore Fungi Antrodia spp. and Oligoporus placenta
Authors: Schmidt O. , Moreth U.
Published: September 2004

Antrodia vaillantii (DC.: Fr.) Ryv., A. serialis (Fr.) Donk, A. sinuosa (Fr.) P. Karsten, A. xantha (Fr.: Fr.) Ryv. and Oligoporus placenta (Fr.) Gilb.& Ryv. form a group of internal brown-rot fungi (‘Porenschwämme’), which are associated with decay of coniferous woodwork in buildings and timber in ground contact. The fungi have similar occurrence, biology, fruit bodies and mycelia. Their nomenclature has a confusing history and is still not uniform. For a better understanding of the domestic pore fungi and for a reliable species differentiation and identification of isolates, the internal transcribed spacer (ITS) of the ribosomal DNA (rDNA) was amplified by polymerase chain reaction and sequenced. Isolates from decayed wood and from culture collections were used. The ITS sequences characteristic of A. vaillantii, A. serialis,A. sinuosa, A. xantha and O. placenta were obtained and deposited in the international databases. The ITS size ranges from 636 to 668 bp. Intraspecific variation was low. A dendrogram was performed for the phylogenetic relationship. Some isolates obtained mislabelled were named correctly according to the ITS sequence. The sequences contribute to our collection of ITS data from internal wood decay fungi made to characterize fungi in culture.
Nanoparticles for the Controlled Release of Fungicides in Wood: Soil Jar Studies Using G.Trabeum and T. Versicolor Wood Decay Fungi
Authors: Liu Y. , Laks P. , Heiden P.
Published: September 2004

Nanoparticles containing a fungicide, tebuconazole or chlorothalonil, were prepared as aqueous dispersions to treat sapwood of southern yellow pine (SYP) and birch using conventional pressure treatment methods. The maximum amount of active ingredient (a.i.) delivered into wood was ca. 2 kg a.i./m3 wood with tebuconazole-containing and 1.6 kg a.i/m3 wood with chlorothalonil-containing nanoparticles. Nanoparticles were prepared using polyvinylpyridine (PVPy) and polyvinylpyridine-co-styrene with 10% styrene (PVPy-10%-Sty) and with 30% styrene (PVPy-30%-Sty) as matrices. Soil jar tests were performed where nanoparticle-treated SYP was exposed to Gloeophyllum trabeum for 16 weeks and nanoparticle-treated birch was exposed to T. versicolor for 12 weeks. Following exposure to G. trabeum, SYP lost ca. 5% of its mass when treated with tebuconazole-containing nanoparticles (PVPy, PVPy-10%-Sty, PVPy-30%-Sty) with a tebuconazole content of ca. 0.5 kg a.i./m3 SYP. Similar results were obtained with chlorothalonil-treated SYP (0.5 kg a.i./m3) with PVPy-10%-Sty and PVPy-30%-Sty. Birch exposed to T. versicolor lost ca. 5% mass when tebuconazole (in PVPy and PVPy-30%-Sty) was ca. 0.5 kg a.i./m3, while similar results were found with chlorothalonil (PVPy, PVPy-10%-Sty, PVPy-30%-Sty) only at a biocide content of ca. 1.6 kg/m3 wood.
A Density Functional Theory Study of Coniferyl Alcohol Intermonomeric Cross Linkages in Lignin - Three-Dimensional Structures, Stabilities and the Thermodynamic Control Hypothesis
Authors: Durbeej B. , Eriksson L.A.
Published: September 2004

Density functional theory methods are utilized to investigate structural features and stabilities of the most common lignin dimerization products. It is found that intra-molecular hydrogen bonding acts as a stabilizing force in the lowest-energy conformer(s) of several different dimeric lignin structures. Furthermore, the calculations show that the hypothesis of thermodynamic control of monolignol dimerization accounts for some of the results obtained in experimental studies aimed at determining the ratios of intermonomeric linkages. A quantitative correlation between experimentally observed ratios and calculated relative energies cannot, however, be pointed out.
Inhomogeneities in the Chemical Structure of Spruce Lignin
Authors: Önnerud H. , Gellerstedt G.
Published: September 2004

Thioacidolysis, periodate oxidation and size exclusion chromatography (SEC) were used for the analysis of spruce lignin samples. The standard thioacidolysis method was modified by including a pre-swelling of the lignocellulosic sample before the reaction, and this gave a higher yield of monomer products. Middle lamella and compression wood lignin was found to contain a larger amount of oligomers after thioacidolysis than normal wood lignin. Analysis by thioacidolysis of a thermomechanical pulp (TMP) revealed that approximately 10% of the β-O-4 structures in the lignin were cleaved due to the mechanical grinding effect. From kraft pulp, the mixture of thioacidolysis products contains a major fraction having a considerably larger molecular mass than the products from spruce wood and TMP. The structure of this material is still unknown.
Application of ESR Spectroscopy in Bleaching Studies
Authors: Cardona-Barrau D. , Matéo C. , Lachenal D. , Chirat C.
Published: September 2004

In this study several pulp components were characterized by ESR spectroscopy. Free radicals present in the pulp lignin gave a well-defined signal, and the residual lignin content during a bleaching sequence could be followed using this technique. Organic radicals on the pulp carbohydrates were also detected and could be related to the formation of chromophore structures in pulp. Further, ESR spectroscopy made it possible to characterize several transition metal ions in pulp. Special attention was paid to metal retention and the impact of a sodium borohydride treatment, and the formation and evolution of complexes between metal ions and pulp components was scrutinized.
Ozone Bleaching of Atmospheric Acetic Acid Hardwood Pulp from Betula platyphylla var. japonica Hara
Authors: Kishimoto T. , Tsuji H. , Uraki Y. , Sano Y.
Published: September 2004

Atmospheric acetic acid pulp from Japanese white birch was bleached with 1–5% ozone with and without intermediate mild alkaline extraction. Concentrated acetic acid was a more effective bleaching media than water. Mild alkaline extraction of ozone-prebleached pulp was found to be very effective in delignification of the pulp and did not have any undesirable effects on pulp properties. A sufficiently delignified acetic acid pulp was obtained with multi-stage ozone bleaching in Z1Z2Z3 or Z1EZ2EZ3 bleaching sequence with a total ozone consumption of 2.17% on oven-dry pulp. The pulp from a Z1EZ2EZ3 sequence still contained 3.51% acetyl groups, which was 75% of the original amount of acetyl groups in unbleached acetic acid pulp.
Relationship Between Growth Stress, Mechanical-Physical Properties and Proportion of Fibre with Gelatinous Layer in Chestnut (Castanea Sativa Mill.)
Authors: Clair B. , Ruelle J. , Thibaut B.
Published: September 2004

A range of mechanical and physical properties were determined for 96 specimens of chestnut wood and for wood types ranging from compression to tension wood; tests included (1) growth stress, (2) longitudinal Young's modulus in green and air-dried states (3) shrinkage in longitudinal and tangential directions. Anatomical observations permitted determination of the proportion of fibres with a gelatinous layer. The influence of these atypical fibres on macroscopic wood properties is examined and discussed. A basic model is proposed to determine their properties in theoretically isolated conditions.
Selected Properties of Parallel Strand Lumber Made from Southern Pine and Yellow-Poplar
Authors: Liu Y. , Lee A.W.C.
Published: September 2004

This study was conducted to explore basic physical and mechanical properties of parallel strand lumber (PSL) made exclusively from southern pine and yellow-poplar, respectively, and to examine their relationships using statistical analysis. Small specimens were prepared from commercial southern pine PSL and yellow-poplar PSL billets and tested for specific gravity, moisture content, dimensional stability, bending properties, shear strength and compressive strength. Results indicate average specific gravity of southern pine PSL is higher than that of yellow-poplar PSL, while their average moisture content and dimensional stability are very similar. Southern pine PSL has higher average modulus of elasticity but lower average modulus of rupture than yellow-poplar PSL. While average longitudinal shear strength does not exhibit differences between southern pine PSL and yellow-poplar PSL, average compressive strength of southern pine PSL is higher than that of yellow-poplar PSL. There are positive correlations among modulus of elasticity, modulus of rupture and specific gravity. PSL improves some properties of solid wood from which PSL is made.
Effects of Cell Structure on Water Sorption for Wood
Authors: Nakano T.
Published: September 2004

Contributions of the cell structure of wood to water sorption were examined using the chemical potential change induced by restrained swelling. Thermodynamic analysis revealed that this potential was proportional to the product of moisture content and the bulk modulus of the restraining region in the wood. The modulus of the restricting region, which was calculated from isotherm curves of wood powder and block samples by using the thermodynamically derived relationship, was near that obtained from the swelling strain and stress in the cross section for whole wood. These results demonstrated that S1 and S3 layers in the cell wall, where thin crystal threads called microfibrils are wound helically in the circumference, act to resist swelling so that the isotherm curve of the block sample was lower than that of wood powder.
Moisture Dynamics in Norway Spruce and Scots Pine during Outdoor Exposure in Relation to Different Surface Treatments and Handling Conditions
Authors: Elowson T. , Bergström M. , HämälÄinen M.
Published: September 2004

Moisture dynamics in wood during weather exposure as affected by species, origin, production method and painting system were studied for nine years on 170 samples. The moisture content (MC, by dry base) was measured on 67 occasions. Principal component analysis was used for data reduction and pattern recognition. The investigation included two species; Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. (Karst)), and showed that the painting method affected the moisture dynamics most. In addition, species and type of wood were important factors, and for pine sapwood also the production method used had an influence on the moisture dynamics. Heartwood of pine had a stable development with low MC throughout the experimental time, regardless of surface treatment or handling method. The pine sapwood samples, on the other hand, had higher average MC and much faster dynamics. For painted and endsealed pine sapwood samples, the drying method was not significant for the MC dynamics, but water storage led to a higher and faster moisture uptake than for samples that were not water-stored. For untreated pine sapwood samples, air-drying led to the highest and fastest moisture uptake, but on the whole this group had unacceptably high moisture uptake. The spruce samples showed very different behaviour depending on whether they were surface treated or not. Painted and endsealed spruce led to two distinct groups, one with moisture dynamics similar to pine heartwood and one with very high moisture uptake and large spread more similar to pine sapwood. Most untreated spruce samples had moisture dynamics comparable to those of pine heartwood.
Post-Harvest Chemical Staining in Blackwood (Acacia melanoxylon R. Br.)
Authors: Barry K. M. , Davies N. W. , Mohammed C. L. , Beadle C. L.
Published: September 2004

This is the first report of post-harvest wood staining in blackwood (Acacia melanoxylonR. Br). In Tasmanian sawmills, an orange-brown stain commonly occurs upon cutting fresh blackwood. An investigation of the causal mechanism of stain development was completed using fresh flitches and stockpiled logs. Some fungi and bacteria were isolated from stained and unstained blackwood, but no species was consistently present in stained wood alone. Wood pH did not vary between stained and unstained wood, but there was some evidence of alterations in phenol composition. Blackwood extracts were analysed by HPLC and a minor phenolic compound was detected that was consistently found in stained samples and rarely in unstained. UV spectra indicated that this compound may be a quinone, but mass spectrometry data was inconclusive. Experiments with blackwood extracts showed that addition of oxygen (by means of H2O2treatment) increased absorbance in the “brown” wavelengths characteristic of stain. This supports the assumption that the stain is an oxidative chemical stain, as it develops quite rapidly from cut surfaces.
Albino Strains of Ophiostoma Species for Biological Control of Sapstaining Fungi
Authors: Held B. W. , Thwaites J. M. , Farrell R. L. , Blanchette R. A.
Published: September 2004

Albino strains ofOphiostoma floccosum,O. piceaeandO. pluriannulatumwere selected and screened for biological control of sapstaining fungi on New Zealand radiata pine (Pinus radiata). Albino strains were obtained through matings and single ascospore isolations from cultures of prevalent species in New Zealand. These strains do not synthesize the melanin-like hyphal pigments of common sapstaining fungi. Additional mating studies were also carried out to obtain isolates ofO. piceaeandO. floccosumthat lacked pigmented fruiting structures. Several albino isolates ofO. piceaewith colorless synnemata and isolates ofO. floccosumwith little to no synnemata were obtained. Biological control potential of the albino isolates was evaluated in the laboratory by challenging them on wood chips with fungi that cause extensive sapstain in pine,Leptographium procerum,Ophiostoma piliferumandSphaeropsis sapinea. Many albino isolates ofO. floccosum,O. piceaeandO. pluriannulatumwere effective in stopping the challenge fungi from staining wood chips and were fast growing and colorless when grown unchallenged on wood chips. Selected albino isolates ofO. pluriannulatumwere used in two field trials in New Zealand to control sapstain. Several strains were found to significantly reduce dark sapstain as compared to the untreated control logs.
A Method to Estimate Fibre Length Distribution in Conifers Based on Wood Samples from Increment Cores
Authors: Mörling T. , Luna S. Sjöstedt-de , Svensson I. , Fries A. , Ericsson T.
Published: September 2004

We propose a method to estimate fibre length distribution in conifers based on wood samples from
increment cores processed by automatic optical fibre-analysers. Automatic fibre-analysers are unable
to distinguish: a) fibres from other tissues, “fines”, and b) cut from uncut fibres. However, our
proposed method can handle these problems if the type of distributions that fibre lengths and fines
follow is known. In our study the length distributions of fines and fibres were assumed to follow
truncated normal distributions, characterised by means and standard deviations of the two distributions.
Parameter estimates were obtained by the maximum likelihood method. Wood samples
from two 22-year-old Scots pine trees at breast height were used to evaluate the performance of
the method. From stem discs at 1.5 m, adjacent samples of 5 mm increment cores and wood pieces
were taken. The cores were trimmed 1 mm at each side and samples were, after maceration,
analysed in a Kajaani FiberLab 3.0. The results showed that the method works well and gives a
possibility to distinguish fine and fibre length distribution.
Surface Fractal Dimensionality and Hygroscopicity for Heated Wood
Authors: Nakano T. , Miyazaki J.
Published: September 2004

The relationship between hygroscopicity and the microsurface of heated wood was examined using
the fractal surface dimensionality. The hygroscopicity of heated wood decreased with the increase
in heating temperature to 250°C, and then decreased again above 350°C after increasing up
to 350°C. This change corresponded to chemical changes in the wood, especially a reduction in hydroxyl
groups, up to 250°C, and to the temperature dependence of the fractal dimensionality calculated
from nitrogen gas adsorption above 250°C. The fractal dimensionality increased gradually
from 100 to 250°C, followed by a rapid increase above 250°C with a peak at 350°C, and leveled off
above 400°C. From the results, it is concluded that hygroscopicity of heated wood changes at
250°C and that it is dependent upon the chemical properties of wood below 250°C and upon the
surface complexity above 250°C.
Wettability of Heat-Treated Wood
Authors: Pétrissans M. , Gérardin P. , bakali I. El , Serraj M.
Published: September 2004

The aim of this work was to study the wettability and chemical composition of heat-treated wood.
Heat treatment was performed at 240°C under inert atmosphere on four European wood species
(pine, spruce, beech and poplar). Contact angle measurements before and after treatment indicated
a significant increase in wood hydrophobicity. Advancing contact angles of a water drop were in
all cases systematically higher for heat-treated than for untreated wood. Chemical modifications
of wood after heat treatment were investigated using FTIR and 13C NMR analysis. FTIR spectra
indicated little structural change which could be attributed either to carbon-carbon double bond
formation or to adsorbed water. NMR spectra also revealed little chemical change except for the
degree of cellulose crystallinity which was considerably higher in heat-treated wood and could explain
the higher contact angles.
Effects of Thermal Conductivity Data on Accuracy of Modeling Heat Transfer in Wood
Authors: Olek W. , Weres J. , Guzenda R.
Published: September 2004

Data sets of wood thermal properties differing in their complexity are presented and discussed. A
number of numerical experiments of the heat transfer in wood are performed, and the predicted
temperatures are compared to the experimental data obtained for European beech and Scots pine
wood. The analysis of similarity of the heat transfer model together with the different empirical
data of wood thermal properties to the results of the experiments showed that the lowest accuracy
of temperature prediction was obtained for the constant data. Application of advanced models of
the thermal conductivity required a large amount of input data and sometimes gave relatively low
accuracy in temperature prediction. Application of the thermal conductivity models developed by
the authors with the use of the Inverse Heat Transfer Problem approach produced the best temperature
prediction accuracy.
Detection of the Fracture Path under Tensile Loads through in situ Tests in an ESEM Chamber
Authors: Frühmann K. , Burgert I. , Stanzl-Tschegg S. E.
Published: September 2004

In situ tensile tests parallel to the grain were carried out in an Environmental Scanning Electron
Microscope (ESEM) chamber on Norway spruce (Picea abies [L.] Karst.) samples. The ESEM-mode
combined with a cooling device allowed examination of the specimens at a moisture content
of 12% with unsputtered surfaces. By recording load-displacement curves and observing crack
propagation simultaneously, a detailed image of fracture progress and tissue interaction could be
described. Since these experiments required a sufficient specimen size and geometry, focus was
concentrated on the methodology.
Detection and Species Identification of Wood-Decaying Fungi by Hybridization of Immobilized Sequence-Specific Oligonucleotide Probes with PCR-Amplified Fungal Ribosomal DNA Internal Transcribed Spacers
Authors: Oh S. , Kamdem D. P. , Keathley D. E. , Han K.-H.
Published: September 2004

We developed an effective detection method for wood-decaying fungi by hybridization of immobilized Sequence-Specific Oligonucleotide Probes with florescent-labeled PCR-amplified fungal rDNA internal transcribed spacer sequences. This method takes advantage of both the sequence specificity of Southern blot hybridization and the sensitivity of the previously reported PCR-based fungal species identification methods. Bothin vitrocultured fungal strains and naturally decaying wood samples were used to demonstrate that this method is robust and practical for detection of incipient wood-decaying fungi. It can be a useful tool for microbial ecology, plant pathology, protection of wood products in service, preservation efforts for high-value furniture and wood-based art and DNA fingerprinting for tracking the source of contamination of wood decay fungi.
Analysis of Protein Expression along the Normal to Tension Wood Gradient in Eucalyptus gunnii
Authors: Plomion C. , Pionneau C. , Baillères H.
Published: September 2004

This paper examines the contribution of various xylem proteins to wood formation inEucalyptus gunnii. Proteins were extracted from differentiating xylem harvested from a crooked tree, separated by high-resolution two-dimensional polyacrylamide gel electrophoresis, visualised by silver nitrate staining and analysed with a computer-assisted system for single protein spot quantification. Growth strain measurements allowed xylem samples to be classified quantitatively from tension wood to normal wood. Regression of lignin content on growth strain showed that a decrease in lignin content corresponded to decreasing growth strain values,i.e., presence of tension wood. Out of the 140 studied protein spots, 12 were significantly associated with growth strain: 7 being less abundant in tension wood and 5 being more abundant in tension wood. A clustered-correlation analysis was performed to study protein expression simultaneously along the gradient of gravistimulated stressed xylem tissue. Proteins were found to form “expression clusters”.
Lignin Structures in Normal and Compression Wood. Evaluation by Thioacidolysis Using Ethanethiol and Methanethiol
Authors: Önnerud H.
Published: September 2004

The chemical structure of lignin in normal and compression wood of spruce has been studied.
Thioacidolysis using both methanethiol and ethanethiol as nucleophiles was used for degradation.
The results showed that these nucleophiles work equally well in thioacidolysis, but that
methanethiol gives a somewhat higher yield than ethanethiol. In spruce compression wood, several
of the monomeric, dimeric and trimeric products were structurally elucidated using gas chromatography-mass spectrometry analysis of the desulphurated thioacidolysis products. Some of the
oligomeric structures contained a p-hydroxyphenyl unit, but most of the material seemed to be
present in non-condensed β-O-4 structures. A catechol structure was found and the results also indicated
the presence of β-5 stilbene structures in native spruce lignin.
Lignin-Carbohydrate Condensation Product Formation in a Biomimetic Model Pulp Bleaching System
Authors: Walker C. C. , McDonough T. J. , Dinus R. J. , Eriksson K.-E. L.
Published: September 2004

Three biomimetic compounds were evaluated for their ability to preferentially degrade lignin in
the presence of carbohydrate using two water-soluble polymeric model compounds: lignosulfonate
and hydroxyethyl cellulose (HEC). The three biomimetic systems studied were FeSO4, Fe-EDTA and hemoglobin, each in the presence of hydrogen peroxide. When both polymeric substrates
were present, a high molecular weight product was observed to form upon addition of
H2O2. This high molecular weight product is believed to be the result of a condensation reaction
between lignosulfonate and HEC. The condensation product was also observed to form in the absence
of biomimetic catalyst.

For all reactions, the molecular weight of the condensation product was observed to decrease
with increasing reaction time. By altering the ratio of lignosulfonate to HEC, a limit was observed
in the relative amount of condensation product formed. The formation of this condensation product
is believed to limit the effectiveness of acidic bleaching systems.