scholarly journals Effects of Microwave Treatment on Microstructure of Chinese Fir

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 772
Author(s):  
Xiang Weng ◽  
Yongdong Zhou ◽  
Zongying Fu ◽  
Xin Gao ◽  
Fan Zhou ◽  
...  
Keyword(s):  
High Intensity ◽  
Microwave Treatment ◽  
Chinese Fir ◽  
Drying Time ◽  
Bordered Pit ◽  
Low Intensity ◽  
Micro Cracks ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Ray Parenchyma Cells

Microwave (MW) treatment is an effective method to increase refractory wood permeability, thereby reducing drying time and defects. The extent of modification depends on the damage extent of the wood microstructure. In this study, MW intensities of 43 kWh/m3 (low intensity) and 57 kWh/m3(high intensity) were adopted to treat Chinese fir lumber. Microstructural changes in wood samples were observed using scanning electron microscopy (SEM) and pore structure was characterized using mercury intrusion porosimetry (MIP). Results were as follows: After low-intensity MW treatment, parts of the bordered pit membranes in tracheids were damaged, and micro-fibrils on the margo were ruptured, while the torus basically remained intact. Micro-cracks were observed at both ends of the cross-field pit apertures, propagating to the cell walls of tracheids. The middle lamellar between ray parenchyma cells and longitudinal tracheids cracked, and the width of cracks was in the range of 1–25 μm. After high-intensity MW treatment, damage to the wood microstructure was more severe than that in the low-intensity MW treatment, with macro-cracks having a width range of 100–130 μm being generated. In addition, on the fracture surface of macro-cracks, the bordered pit membranes in tracheids fell off, cross-field pit membranes disappeared and the ray parenchyma cells were seriously damaged, exhibiting fracture of the tracheid walls. Both low-intensity and high-intensity MW treatment can increase the pore diameter corresponding to the margo capillaries (peak value increased from 674.7 nm to 831.8 nm and 1047.6 nm, respectively). The number of pores in the tracheid lumen diameter range also significantly increased. These results provide a theoretical support forMW treatment processes’ improvement and high-value utilization of Chinese fir.

Wound Effects on Xylem Cell Differentiation in a Conifer

IAWA Journal ◽  
1984 ◽  
Vol 5 (4) ◽  
pp. 295-305 ◽  
Author(s):  
Keiko Kuroda ◽  
Ken Shimaji
Keyword(s):  
Cell Differentiation ◽  
Loblolly Pine ◽  
Parenchyma Cell ◽  
Cell Maturation ◽  
Bordered Pit ◽  
Xylem Cell ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
Cambial Zone ◽  
Ray Parenchyma Cells

Modified xylem cells formed around a minute injury due to pin insertion in the cambium of loblolly pine stern were observed periodically in order to study the mechanism of xylem cell differentiation in conifers. Ray parenchyma cells in the mature xylem as well as in the cambial zone were strongly activated. They not only proliferated randomly in the wound gap, but also invaded into some mature tracheids through the pinoid pits to form tylosis-like structures. Then they reticulately thickened and lignified their wall much earlier and more excessively than the normal ray parenchyma cells. Immature ray tracheids, which also divided several times abnormally in the cambial zone, differentiated into ray tracheids without differentiating into any other elements, although some of them had modified pits. Immature axial tracheids near the injury differentiated normally even though some sporadic transverse or radial division occurred before maturation. Only exceptionally, some peculiar groups of small bordered pit pairs were formed between them. It was clear that a shift from differentiating direction on the way of cell maturation, for instance from immature tracheid to parenchyma cell, was never induced by injury. Cambial initials, both ray and fusiform, were very stable.

scholarly journals Effects of microwave pretreatment on drying of 50 mm-thickness Chinese fir lumber

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Xiang Weng ◽  
Yongdong Zhou ◽  
Zongying Fu ◽  
Xin Gao ◽  
Fan Zhou ◽  
...  
Keyword(s):  
Chinese Fir ◽  
Drying Process ◽  
Drying Time ◽  
Moisture Migration ◽  
Appearance Quality ◽  
Micro Cracks ◽  
Conventional Drying ◽  
Drying Behavior ◽  
Ray Parenchyma Cells

AbstractLow permeability of wood causes problems during drying of timber. This study evaluated the effects of microwave (MW) pretreatment on the conventional drying behavior and mechanical damages of Chinese fir lumber. MW pretreatment of lumber was performed at applied MW energy of 43 kWh/m3, and then, the samples were dried in a laboratory drying kiln. The results showed that the drying rate was effectively increased after MW pretreatment. The moisture content (MC) deviation in thickness and residual stress indexes of MW-pretreated samples were significantly decreased in comparison with the control samples, and the appearance quality of wood samples was not clearly affected by the MW pretreatment. Scanning electron microscope (SEM) micrographs demonstrated that pit membranes were damaged after MW pretreatment, and the micro-cracks in radial section as well as detachments between ray parenchyma cells and tracheids were also observed. Consequently, new pathways for moisture migration during drying process were formed after MW pretreatment, which contributed to the improved permeability of Chinese fir lumber and decreased drying time.

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.

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