Effect of ammonia treatment on white birch wood

Yamashita, Daichi,Kimura, Satoshi,Wada, Masahisa,Samejima, Masahiro,Takabe, Keiji Walter de Gruyter und Co 2018 Holzforschung Vol.72 No.1

<P><B>Abstract</B></P><P>Transverse sections of white birch (<I>Betula platyphylla</I>) were treated with anhydrous ammonia at 60-140°C (ammonia treatment, AT). As a result, the crystal structure of cellulose in the AT samples changed to cellulose III<SUB>I</SUB>, and acetamide was produced. The surface area of the AT samples, the amount of sugar released upon acid hydrolysis and the lignin content were not changed. However, a small amount of lignin became acid soluble. Mäule color reaction, indicative of the presence of syringyl lignin, showed decreasing color intensities with increasing temperature of AT. The results can be easily interpreted that AT affects ester linkages and side chains of hemicelluloses and syringyl lignin. In addition, AT was carried out on 1-μm thick transverse sections and block specimens. Xylanase treatment and immunolabeling revealed that AT enhances xylan degradation, but ray cells are resistant to xylanase even after AT. On the block sample, a deposited xylan layer appeared on the inner surface of fiber cell walls. Apparently, xylan moved to the surface in contact with the fluid ammonia during AT. The vessel cell wall did not show a similar migration effect, indicating a cell wall-specific interaction with ammonia.</P>

Phylogenetic analysis of wood-inhabiting molds and assessment of soft-rot wood deterioration. Part 5. Genus <i>Aureobasidium</i>

Lee, Young Min,Lee, Hanbyul,Heo, Young Mok,Hong, Joo-Hyun,Jang, Seokyoon,Kang, Kyu-Young,Kim, Jae-Jin Walter de Gruyter und Co 2017 Holzforschung Vol.71 No.5

<P><B>Abstract</B></P><P>The genus<I>Aureobasidium</I>is wellknown as a wood-staining mold and as a black yeast-like fungi, which produces mainly dark spores or pigmented hyphae within the wood cell lumens. Nevertheless, few studies are dedicated to wood-colonizing<I>Aureobasidium</I>species and little is known about the wood degradation patterns of this genus. In the present study, four<I>Aureobasidium</I>species, including<I>Aureobasidium melanogenum</I>,<I>Aureobasidium leucospermi</I>,<I>Aureobasidium pullulans</I>, and an unknown<I>Aureobasidium</I>sp., were isolated and identified based on phylogenetic analysis.<I>A. melanogenum</I>and<I>A</I>.<I>leucospermi</I>were observed for the first time in Korea. The degradation pattern of Douglas-fir by<I>Aureobasidium</I>was observed for the first time by scanning electron microscopy (SEM). All tested<I>Aureobasidium</I>species except an unknown<I>Aureobasidium</I>sp. revealed soft-rot Type ΙΙ (erosion) in sapwood pine.</P>

Characteristics of carbon nanofibers produced from lignin/polyacrylonitrile (PAN)/kraft lignin-g-PAN copolymer blends electrospun nanofibers

Park, Chan-Woo,Youe, Won-Jae,Han, Song-Yi,Kim, Yong Sik,Lee, Seung-Hwan Walter de Gruyter und Co 2017 Holzforschung Vol.71 No.9

<P>Lignin-based electrospun nanofibers (eNFs) were prepared and thermally stabilized at 250 degrees C and subsequently carbonized at 1400 degrees C. The starting blend was prepared in dimethyl formamide (DMF) solution with lignin and polyacrylonitrile (PAN), while a lignin-grafted-PAN (L-g-PAN) copolymer served as compatibilizer. The viscosity was highest of the DMF solution with PAN, and decreased for the lignin/PAN blends and additionally in presence of L-g-PAN. The uniform eNFs with clean surfaces dispose of diameters between 400 nm and 1 mu m. The average diameter of eNFs decreased by the thermal treatment and at higher lignin contents in the blends. Remarkable shrinkage by carbonization was observed in all nanofibers. The successful carbonization of all electrospun carbon nanofibers (eCNFs) was confirmed by Fourier transform-infrared (FT-IR) spectroscopy. The specific tensile strength and elastic modulus of the eCNF mats from lignin/PAN blends were improved by the addition of L-g-PAN, and it can be safely concluded that it acts as a compatibilizer between lignin and PAN.</P>

Improvement of shear strength, wood failure percentage and wet delamination of cross-laminated timber (CLT) panels made with superheated steam treated (SHST) layers of larch wood

Han, Yeonjung,Park, Yonggun,Chang, Yoon-Seong,Chung, Hyunwoo,Eom, Chang-Deuk,Yeo, Hwanmyeong Walter de Gruyter und Co 2017 Holzforschung Vol.71 No.11

<P>Cross-laminated timber (CLT) panels - consisting of several cross-wise stacked layers of glued boards - have a high dimensional stability. However, the outer surfaces of CTL are exposed to environmental humidity changes and thus to swelling and shrinking. To improve CLT's dimensional stability further, the layers of kiln dried (KD) CLT were substituted partly (on the surfaces) and entirely with superheated steam treated (SHST) wood. The effects of SHST wood and the performance of the one-component polyurethane resin (PUR) were tested by block shear and delamination tests after water soaking. Under various conditions, the shear strength ranged from 1.3 MPa to 4.7 MPa and the wood failure percentage (WFP) from 76% to 92%. The optimal parameter were ascertained as pressing time (30-45 min), pressure (0.98 MPa) and adhesive amount (175-200 g m(-2)). The water soaked delamination of CLT manufactured with SHST wood was approximately 50% lower than that of CLT made of KD wood.</P>

Optimization study on acid hydrolysis of hardwood-derived hemicellulosic extract for alcohol fermentation using response surface methodology

Park, Seong Jik,Um, Byung Hwan Walter de Gruyter und Co 2015 Holzforschung Vol.69 No.2

<B>Abstract</B><P>In this study, the extraction conditions of hemicelluloses from mixed hardwoods have been tested. In particular, 3% total titrated alkaline (TTA) green liquor (GL) was used to dissolve certain hemicelluloses and lignin in a manner similar to black liquor extraction, but the pH was maintained at near-neutral conditions, so that oligosaccharides were not completely degraded into isosaccharinic acids. The effects of temperature, time, and acid concentration on the fermentable sugar yields for the extract during secondary hydrolysis were investigated. Chips of mixed northern hardwoods were cooked in a rocking digester at 160°C for 110 min in the GL at a concentration of 3% Na2O-equivalent salts on dry wood. The mass of wood extracted into the GL extract was approximately 11.4% of the debarked wood mass, which resulted in a dilute solution of oligomeric hemicellulosic sugars. Dilute sulfuric acid hydrolysis was performed under the following conditions: 100°C-130°C, 2%-4% H2SO4, and 20-120 min residence time. The maximum fermentable sugar concentration of xylose, mannose, and galactose (XyMaGa) obtained from the hydrolyzed extract was 5.5 g l<SUP>-1</SUP>, representing 91.7% of the maximum possible yield. A factorial design was used to study the effects of temperature and acid concentration on the maximum quantity of XyMaGa oligomers obtained in the extract during secondary hydrolysis. The maximum potential yield of XyMaGa reached 5.34 g l<SUP>-1</SUP>at 130°C, 3.27% H2SO4, and 50.2 min residence time.</P>

Epimeric phenylpropanoid glycosides from inner bark of Paulownia coreana Uyeki

Kim, Jin-Kyu,Si, Chuan-Ling,Bae, Young-Soo Walter de Gruyter und Co 2007 Holzforschung Vol.61 No.2

<B>Abstract</B><P>Three epimeric phenylpropanoid glycosides have been isolated from the aqueous acetone extract of <I>Paulownia coreana</I> inner bark. One compound is new and its structure has been established by spectroscopic methods as <I>R,S-</I>7″′-(3″′,4″′-dihydroxyphenyl)-ethyl-<I>O</I>-α-L-rhamnopyranosyl(1″→3′)-β-D-(6′-<I>O</I>-caffeoyl)-glucopyranoside.</P>

Sap-staining fungi from logs and boards of two commercially important pines in Korea

Kim, Gyu-Hyeok,Kim, Jae-Jin,Breuil, Colette Walter de Gruyter und Co 2007 Holzforschung Vol.61 No.3

<B>Abstract</B><P>To collect more information about the organisms causing sap-stain, a thorough survey was conducted in Koreas sawmills that process logs and boards of Japanese red pine and Korean pine. Sap-staining fungi were isolated and identified using morphological and molecular methods. The 482 isolates obtained were distributed into at least nine species of ophiostomatoid fungi. In both pine species, the frequency of ophiostomatoid isolates was much higher in boards than in logs. Three species<I>, Ophiostoma koreanum</I>,<I>O. floccosum</I>, and<I>O. piliferum</I>, were found on both logs and boards. Two<I>Pesotum</I>species from Japanese red pine were isolated only from logs. Our results show that the dominant species in both logs and boards was<I>O. koreanum</I>from Korean pine. However,<I>O. koreanum</I>,<I>O. floccosum</I>, and<I>O. ips</I>were the most frequently found species in this study.</P>