A single cell model for pretreatment of wood by microwave explosion

Holzforschung ◽  
2010 ◽  
Vol 64 (5) ◽  
Author(s):  
Xianjun Li ◽  
Yongdong Zhou ◽  
Yonglin Yan ◽  
Zhiyong Cai ◽  
Fu Feng
Keyword(s):  
Pressure Difference ◽  
Critical Pressure ◽  
Cell Model ◽  
Circumferential Stress ◽  
Longitudinal Direction ◽  
Critical Conditions ◽  
Maximum Pressure ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Abstract A theoretical model was developed to better understand the process of microwave explosion treatment of wood cells. The cell expansion and critical conditions concerning pressure and temperature of ray parenchyma cells in Eucalyptus urophylla were simulated during microwave pretreatment. The results indicate that longitudinal and circumferential stresses were generated in the cell walls owing to the internal steam pressure during extensive microwave treatment. The circumferential stress is twice as high as the longitudinal stress. The pressure difference reaches its maximum value of 0.84 MPa when the extension ratio is 1.20 for the longitudinal direction and 1.62 for the circumferential direction. The maximum pressure difference at the theoretical yielding point is the critical pressure difference that can eventually rupture the ray cell. The critical pressure difference decreases with increasing cell radius and decreasing shear modulus in the cell wall. This simulated result provides useful information to modify wood at the level of ray parenchyma cells.

Ray Structure Differences between Rootwood and Stemwood in a Range of Softwood Species

IAWA Journal ◽  
2009 ◽  
Vol 30 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Pat Denne ◽  
Siân Turner
Keyword(s):  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Structural Differences ◽  
Ray Parenchyma Cells ◽  
Practical Implications ◽  
Softwood Species

Differences between the ray structure of rootwood and stemwood were analysed in 11 species from 5 families of gymnosperms. Rootwood was consistently found to have fewer ray tracheids, with ray parenchyma cells which were taller axially, wider tangentially, but shorter radially, and had more pits per cross-field than stemwood. A scale for quantifying types of cross-field pitting is proposed, and statistically significant differences in type and diameter of cross-field pitting were found between rootwood and stemwood of most species sampled. These structural differences have practical implications for identification of gymnosperm roots, and for distinguishing between rootwood and stemwood.

Ray Structure in Root- and Stem-Wood of Larix Decidua: Implications for Root Identification and Function

IAWA Journal ◽  
2008 ◽  
Vol 29 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Pat Denne ◽  
Peter Gasson
Keyword(s):  
Wood Anatomy ◽  
Larix Decidua ◽  
Stem Wood ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells ◽  
And Function

Differences in ray structure between root- and stem-wood of softwoods can cause confusion in identifying roots using keys based on stem-wood anatomy. Comparison of root- and stem-wood rays of Larix decidua showed root-wood had fewer ray tracheids, taller, wider but shorter ray parenchyma cells, and larger cross-field pits than stem-wood. The implications of these differences are considered in relation to the identification and function of roots.

INHIBITION OF WATER CONDUCTIVITY CAUSED BY WATERMARK DISEASE IN SALIX SACHALINENSIS

IAWA Journal ◽  
2000 ◽  
Vol 21 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Yasuaki Sakamoto ◽  
Yuzou Sano
Keyword(s):  
Wood Anatomy ◽  
High Moisture ◽  
Water Conductivity ◽  
X Ray ◽  
Salix Sachalinensis ◽  
Water Conduction ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
High Moisture Level ◽  
Ray Parenchyma Cells

Water conduction and wood anatomy of Salix sachalinensis attacked by watermark disease were investigated. The internal symptom, the watermark, appeared as a brown to brown-black stained zone in sapwood. Dye injection tests revealed that water conduction did not take place in the watermark. However, soft X-ray photography and cryo-scanning electron microscopy revealed that the watermark had a high moisture level. In the watermark, some of the vessels were plugged with tyloses and masses of bacteria, and some of the ray parenchyma cells caused necrosis. Hence, the non-conductive watermark in sapwood can be considered similar to discoloured wood or wetwood.

The fine structure of the pits of Eucalyptus regnans (F. Muell.) and their relation to the movement of liquids into the wood

1960 ◽  
Vol 8 (1) ◽  
pp. 51 ◽  
Author(s):  
J Cronshaw
Keyword(s):  
Secondary Wall ◽  
Structural Features ◽  
Cellulose Microfibrils ◽  
Primary Wall ◽  
Detailed Structure ◽  
Eucalyptus Regnans ◽  
Pit Membrane ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Observstion in the electron microscope of carbon replicas of the pits of vessels, ray parenchyma cells, fibres, and tracheids of Eucalyptus regnans has shown the detailed structure of the pit borders and the pit closing membranes. In all cases in the mature wood the primary wall is left apparently without modification as the pit membrane. Unlike the borders of the pits of fibre tracheids and tracheids, the pit borders of the vessels are not separate; the cellulose microfibrils of a border may be common to several pits. The pit borders of fibre traoheids and tracheids are developed as separate entities and have a structure similar to the pit borders of softwood tracheids. The structure of the secondary wall layers associated with the pits is described and related to the structure of the pits. The fine structural features of the pits, especially of the pit closing membranes, are discussed in relation to the movement of liquids into wood.

Silica in Woody Stems

1974 ◽  
Vol 22 (2) ◽  
pp. 211 ◽  
Author(s):  
G Scurfield ◽  
CA Anderson ◽  
ER Segnit
Keyword(s):  
The Other ◽  
X Ray Diffraction ◽  
Xylem Parenchyma ◽  
X Ray ◽  
Woody Perennial ◽  
Internal Surfaces ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells ◽  
Scanning Electron

Scanning electron microscopy has been used to examine silica isolated by chemical means from the wood of 32 species of woody perennial. The silica consists of aggregate grains lying free in the lumina or in ray and xylem parenchyma cells in 24 of the species. It occurs as dense silica in the other species, filling the lumina or lining the internal surfaces of vessels (and fibres) in all cases except Gynotroches axillaris where it is deposited in ray parenchyma cells. Infrared spectra and X-ray diffraction diagrams, obtained for specimens of both sorts of silica, are indistinguishable from those for amorphous silica. Aggregate grain and dense silicas are also alike in that their differential thermal analysis curves show a rather broad endothermic peak between 175° and 205°C. The results are discussed in relation to possible modes of deposition of the two sorts of silica and the tendency for silica in ray parenchyma cells to be associated with polyphenols.

Survival rate and nuclear irregularity index of sapwood ray parenchyma cells in four tree species

1993 ◽  
Vol 23 (4) ◽  
pp. 673-679 ◽  
Author(s):  
K.C. Yang
Keyword(s):  
Survival Rate ◽  
Growth Ring ◽  
Initiation Time ◽  
Heartwood Formation ◽  
Sharp Decline ◽  
Irregularity Index ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells ◽  
Marginal Cells

Survival rate and the newly developed nuclear irregularity index (NII) of sapwood ray parenchyma cells were studied within single trees of four species: Pinusbanksiana Lamb., Piceamariana (Mill.) B.S.P., Abiesbalsamea (L.) Mill., and Populustremuloides Michx. The survival rate of ray parenchyma cells is defined as the number of living earlywood ray parenchyma cells in uniseriate rays, divided by the total number of dead and living ray parenchyma cells recorded, multiplied by 100. NII is defined as the ratio of the number of irregularly shaped nuclei of uniseriate ray parenchyma cells to the total number of the irregular and regular nuclei recorded in earlywood, multiplied by 100. The location where death of ray parenchyma cells was first seen in the sapwood varied with species from the second to the seventh growth ring, counted from the cambium. In general, the marginal cells in the outer sapwood died earlier in a given growth ring than the central cells. The survival rate of the sapwood ray parenchyma cells decreased curvilinearly from the outer or middle sapwood towards the boundary of sapwood and heartwood. Based on survival rate classification, Pinusbanksiana and Populustremuloides are type II species, in which some ray parenchyma cells die in the middle or inner sapwood and the number of dead cells increases from the middle sapwood towards the heartwood. Piceamariana and Abiesbalsamea are type III species, in which some ray parenchyma cells die in outer sapwood and the number of dead cells increases from the outer sapwood towards the heartwood. NII increased from the middle of the sapwood towards the sapwood–heartwood boundary and reached its maximum at the growth ring immediately adjacent to the heartwood. NII increased from May to a maximum in the middle of the growing season and then decreased sharply. The months of sharpest decline of the NII in Pinusbanksiana, Piceamariana, and Populustremuloides were August, July–August, and August–October, respectively. In Abiesbalsamea no sharp decline of NII was observed. The findings of this study are in agreement with those of other investigators who used different criteria to indicate the initiation time of heartwood formation. Thus it appears that NII can be added to the list of indicators that pinpoint the initiation time of heartwood formation.

Wood Anatomy of Bhesa Sinica (Celastraceae)

IAWA Journal ◽  
1990 ◽  
Vol 11 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Zhang Xinying ◽  
Pieter Baas ◽  
Alberta M. W. Mennega
Keyword(s):  
Wood Anatomy ◽  
The Other ◽  
Anatomical Character ◽  
The Family ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

The wood anatomy of Bhesa sinica (Chang ' Liang) Chang ' Liang, the only species of the genus occurring in China, is described in detail and compared with other Celastraceae. Bhesa sinica closely resembles other species of the genus, in e. g. vessels mainly in radial multiples, exclusively scalariform perforations, large and (almost) simple vessel-ray pits; parenchyma in fine irregular bands, in long (over 8-celled) strands; thick-walled, non septate libriform fibres; 1-5-seriate heterocellular rays, and prismatic crystals in chambered axial and ray parenchyma cells. This combination of characters is not known to occur in any of the other genera of the Celastraceae, and most individual wood anatomical character states of Bhesa are also unusual within the family. The isolated position of the genus in the Celastraceae is discussed.

Distributional variation of lignin and non-cellulosic polysaccharide epitopes in different pit membranes of Scots pine and Norway spruce seedlings

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 407-429 ◽  
Author(s):  
Jong Sik Kim ◽  
Geoffrey Daniel
Keyword(s):  
Monoclonal Antibodies ◽  
Norway Spruce ◽  
Scots Pine ◽  
Distribution Patterns ◽  
Staining Intensity ◽  
Rhamnogalacturonan I ◽  
Bordered Pits ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Microdistribution of non-cellulosic polysaccharides in pit membranes of bordered pits (intertracheid pits between adjacent tracheids), cross-field pits (half bordered pits between tracheids and ray parenchyma cells) and ray pits (simple pits in nodular end walls of ray parenchyma cells) was investigated in mature earlywood of juvenile Scots pine and Norway spruce seedlings using immunocytochemistry combined with monoclonal antibodies specific to (1→4)-β-galactan (LM5), (1→5)-α-arabinan (LM6), homogalacturonan (HG, LM19, LM20), xyloglucan (LM15), xylan (LM10, LM11) and mannan (LM21, LM22) epitopes. Using phloroglucinol-HCl and KMnO4 staining, lignin distribution in pit membranes was also examined. Apart from cross-field pit membranes in Scots pine, all pit membranes observed showed a positive reaction for lignin with differences in staining intensity. Ray pit membranes showed strongest reaction with lignin staining in both species. Intensity of lignin staining in bordered pit membranes was stronger in Norway spruce than in Scots pine. With localization of non-cellulosic polysaccharide epitopes, Scots pine showed differences in cross-field pit membranes (rhamnogalacturonan-I (RG-I), HG and xyloglucan epitopes) from bordered and ray pit membranes (RG-I and HG epitopes). In contrast, Norway spruce showed significant differences in ray pit membranes (RG-I, HG, xyloglucan, xylan and mannan epitopes) from bordered and cross-field pit membranes (HG and no/trace amount of RG-I epitopes). Distributional differences in HG epitopes depending on antibody type/ membrane regions were also observed in cross-field pit membranes between the two species. Together, the results suggest that distribution patterns of lignin and non-cellulosic polysaccharides in pit membranes differ significantly between pit types and between Scots pine and Norway spruce. Compared with the same types of pit membranes in hardwoods, the results for Scots pine and Norway spruce (softwoods) differed significantly.

Topochemical Characterisation of Phenolic Extractives in Discoloured Beechwood (Fagus sylvatica L.)

Holzforschung ◽  
2003 ◽  
Vol 57 (4) ◽  
pp. 339-345 ◽  
Author(s):  
G. Koch ◽  
J. Puls ◽  
J. Bauch
Keyword(s):  
High Performance ◽  
Cellular Level ◽  
Uv Absorbance ◽  
Methanol Extracts ◽  
Absorbance Maximum ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Fagus Sylvatica L ◽  
Ray Parenchyma Cells ◽  
Uv Microspectrophotometry

Summary 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.

Sign in / Sign up

Export Citation Format

Share Document