Wood Rays Research Articles

Influence of N,N-dimethylformamide on one-component moisture-curing polyurethane wood adhesives

The influence of the solvent N,N-dimethylformamide (DMF) on one-component moisture-curing polyurethane (1C-PUR) bonded wooden specimens was investigated. The applied methods were ATR-IR spectroscopy, VIS-NIR spectroscopy, FT-IR microscopy, UV Fluorescence microscopy, Nanoindentation, and AFM imaging. Findings reveal that DMF influences the curing kinetics of the 1C-PUR, supporting its thorough conversion by affecting the morphology and mechanical properties of the cured adhesive. Furthermore, DMF partially dissolves the wood׳s lignin and seems to make bound wood moisture more available for reaction with the adhesive. The outcomes confirm that 1C-PUR enters neither the wood cell walls nor the wood rays. The vessel system of the early wood represents the major pathway for the penetration of 1C-PUR into the beech wood.

The anatomy and grain pattern in forks of hazel (Corylus avellana L.) and other tree species

This paper provides a new anatomical model for how branches are joined together at forks in trees, using evidence from MicroXCT scanning, ESEM output and visual observation. Wood grain arrangements at the forks and other junctions within a tree must be arranged to mechanically join together the two or more branches, yet not adversely restrict sap flow. The grain orientation at junctions therefore represents a trade-off in xylem performance between the functions of efficient sap conductance and the provision of adequate load-bearing capacity. Initial observations of wood grain orientation were made on the surfaces of several dozen debarked and fractured bifurcations of a wide range of tree species, both by eye and using a scanning electron microscope. Subsequently, small volumes of wood were sampled from two locations within the junctions of hazel, at the junction apex and on the outer section of join. Wood was imaged in 3D using high-resolution X-ray tomography, and the scanned volumes were analysed for their wood grain patterns. It was found that the wood at the junctions of hazel forks contained only 37 % of the number of vessels contained in wood within the adjacent stem. The vessel elements formed at the junctions were only 32.5 % the length of those in the stem, had a mean diameter only 50.5 % of the stem vessels and consequently only 26.3 % of their lumen volume. The passage of the vessels through the fork wood deviated from a straight line (Euclidean) distance by more than 14 times more than the stem wood vessels did. The interweaving of vessels in the fork wood was over 22 times greater than in the stem wood. A survey of rays showed them to be 58 % more abundant in fork wood but only 62 % of the height of rays in the stem wood. These results suggest that where two branches of similar diameter join to form a tree fork, an interlocking wood grain pattern is formed at the apex of the bifurcation, which provides higher tensile strength to the junction. Breaking of the hazel fork requires wood fibres to be stretched axially and broken across, which requires greater stress than breaking normal wood radially or tangentially.

Study on Properties of Modified Poplar Wood

The paper based on a comparative study between poplar wood and modified poplar wood, concerning dimensional stability, physical and mechanical properties. The result showed that air-dry density and ASE value of modified wood samples were increasing in different levels with change of the modifier concentration, compared with untreated poplar wood. The air-dry density of modified wood reached 0.41 g/cm3 with increase of 5.3% compared to poplar wood. ASE reached 47.8% and the water-absorption ratio decreased by 38% at most when the modifier concentration was 30 wt.%. Moreover, the MOE and MOR of modified poplar wood increased up to 27.4% and 13% respectively when the modifier concentration was 25 wt.%. The SEM spectrum showed some wood rays and the gaps between staggered fibers were filled by modifier.

A Fossil Dicot Wood Aeschynomenoxylon Mohgaonsesp.Nov From The Deccan Intertrappean Beds Of Mohgaonkalan, M.P., India.

The Deccan Intertrappean flora is mostly silicified and often very well preserved, representing the groups Thallophyta (fungi, algae and charophytes), water ferns, conifers and angiosperms with both monocotyledons and dicotyledons. The present wood is collected from the Deccan Intertrappean beds of Mohgaonkalan. The wood is angiospermic diffuse porus, vessels solitary and in multiples of two, usually small, occasionally of medium size. Xylem parenchyma scanty with paratracheal vasicentri type, Intervascular pitting are simple and alternate.Perforation plate simple. Fibers are non-septate and storied. Wood rays uniseriate only. Rays are homogenous and made up of procumbent cells only. It show its affinities with the reported species of Aeschynomene.

Dynamics of the ray pattern in cambium of Diospyros lotus

Cambial rays, give rise to phloem and xylem rays. This way they affect the efficiency of a radial con- ducting system in a tree. Both, frequency of rays and their arrangement on the expanding cambial surface must be precisely controlled during tree ontogeny. The main aim of this research was to analyse the changes in the ray arrangement of Diospyros lotus L. cambium during transition from its nonstoried to double-storied structure. In order to trace the history of cambial ray dynamics, the behaviour of wood rays was followed in successive annual rings. Special attention was paid to developmental events, such as initiation and elimina- tion of rays as well as their splitting and uniting. Moreover, the additions and eliminations of ray cell initials at the both opposite ray margins were followed. The most evident was the initial split of high primary rays into the smaller parts and their subsequent separation concurrent with the increase in cambial girth during the first years of a tree ontogeny. Between the existing rays new secondary rays were initiated by segmenta- tion of fusiform initials. These all developmental events led to the formation of a double-storied pattern. In addition, the recurrent uniting and splitting of rays indicated their permanent rearrangement and the dy- namic maintenance of a general pattern. The presented data are discussed in light of the processes occurring in cambial rays that lead to the storied pattern formation, which in turn may affect the mechanical properties of the wood.

Borate-Treated Strand Board from Southern Wood Species: Resistance Against Decay and Mold Fungi

Combined decay and mold resistance of zinc borate-(ZB) and calcium borate-(CB) treated oriented strand board (OSB) from southern mixed hardwood (MHW) and southern yellow pine (SYP) was investigated. Tests were done with a brown-rot fungus, Gloeophyllum trabeum, and a white-rot fungus, Trametes versicolor, for 8 and 12 weeks, respectively. Wood species and fungus type had significant influence on the decay resistance. Decay caused by the brown-rot fungus was evident for all untreated SYP and mixed MHW controls. White-rot fungus did not cause significant sample weight loss for either species group. In the SYP OSB control inoculated with G. trabeum, the hyphae were abundant in wood rays and cell walls where they primarily penetrated through bordered and simple pits. The incorporation of ZB and CB into OSB provided significant protection against the fungi with no significant weight loss observed in the treated OSB. Microscopic analysis showed distinct evidence of fungal colonization and a thinning pattern of cell wall material. Untreated OSB samples from MHW and commercial OSBs were most susceptible to mold growth after 6 weeks. The borate-modified OSB from MHW and SYP effectively prevented the mold growth.

Poplar Wood Rays Are Involved in Seasonal Remodeling of Tree Physiology

Understanding seasonality and longevity is a major challenge in tree biology. In woody species, growth phases and dormancy follow one another consecutively. In the oldest living individuals, the annual cycle may run for more than 1,000 years. So far, however, not much is known about the processes triggering reactivation from dormancy. In this study, we focused on wood rays, which are known to play an important role in tree development. The transition phase from dormancy to flowering in early spring was compared with the phase of active growth in summer. Rays from wood samples of poplar (Populus × canescens) were enriched by laser microdissection, and transcripts were monitored by poplar whole-genome microarrays. The resulting seasonally varying complex expression and metabolite patterns were subjected to pathway analyses. In February, the metabolic pathways related to flower induction were high, indicating that reactivation from dormancy was already taking place at this time of the year. In July, the pathways related to active growth, like lignin biosynthesis, nitrogen assimilation, and defense, were enriched. Based on "marker" genes identified in our pathway analyses, we were able to validate periodical changes in wood samples by quantitative polymerase chain reaction. These studies, and the resulting ray database, provide new insights into the steps underlying the seasonality of poplar trees.

On Vertebraria Royle from Triassic of Nidpur, Madhya Pradesh

Abstract The present paper embodies a description of a new species of the vertebrarian axis Vertebraria Royle (1834) from the Triassic Nidpur beds, M.P., India. Structurally preserved axes of the new species Vertebraria nidpurensis occur as horizontal or longitudinal compressions exhibiting excellent features of secondary xylem tissue. The description is based on a single hand specimen, displaying four axes lying in different positions but all exposed in their lateral views. Total length of axes is unknown but the largest specimen is about 7.2 cm long. Width of axes ranges between 0.2 cm – 2.8 cm depending on the number of vertical series of elongated rectangular areas present in the axis. Each vertical file of rectangles is separated from adjacent series by a narrow longitudinal groove. The rectangular area of longitudinal file is separated from the rectangle above and below by a thick or thin transverse bar that extends from one longitudinal groove to the other. Three axes out of four exhibit well preserved secondary tissues that showed features which were quite different from species of Vertebraria reported upto date. The new species differs from all other previously described structurally preserved species in having tracheids that bear pits on both tangential and radial walls and in having wood rays that are 2-35 celled high. Vertebrarian axes of above type are being reported for the first time from Triassic of Nidpur, Madhya Pradesh.

Aspirin to prevent incident cardiovascular disease: is it causing more damage than it prevents?

Cardiovascular disease (CVD) principally encompasses fatal and nonfatal myocardial infarction (MI) and stroke. It remains a major challenge to healthcare with a high incidence, prevalence and mortality; hence, prevention is a highly relevant topic, with many clinical implications. This editorial will briefly cover the established role of aspirin in secondary prevention, then look at why it would be expected to be less useful in primary prevention and, finally, cover the evidence for this hypothesis. There are two aspects to the prevention of CVD: primary and secondary prevention. Primary prevention refers to the reduction of incident disease in essentially healthy subjects believed to be at high risk, whereas secondary prevention refers to prevention of recurrent events in those with prevalent or established CVD. Both primary and secondary prevention involve the management of modifiable risk factors, starting with lifestyle changes (e.g., increasing exercise, improving the diet and smoking cessation). Pharmacological interventions have two different broad aims: drugs such as statins and antihypertensives focus on reducing lowdensity lipoprotein cholesterol and blood pressure, as a means of reducing the development or progression of atheroma and, hence, reducing risk of plaque rupture and a cardiovascular event. By contrast, antiplatelets such as aspirin purely target the final step in this pathway, reducing the likelihood of thrombus formation in patients with a ruptured atherosclerotic plaque. It is important to clarify that the risk profiles of individuals in the primary and secondary prevention cohorts are very different. Patients who have already had an event such as a MI (i.e., second ary prevention) have demonstrated not only that they have atherosclerotic plaque but also that, as a result of genetic predisposition and acquired risk factors, they have a tendency to form acute thrombus. It therefore makes physio logical sense that aspirin would be beneficial in this group, and this is supported Carrie-Anne Ling, Susan Unwin-Golding, Alice Wood & Kausik Ray* Editorial

Variation in wood anatomical properties of selected indigenous, multipurpose tree species grown in research trials at LRS Thiruvazhamkunnu, Palakkad, Kerala

The present study is an attempt to study the variation in wood physical and anatomical properties of Artocarpus heterophyllus Lam., Artocarpus hirsutus Lam. and Pterocarpus marsupium Roxb. raised as part of a provenance trial of the Kerala Agricultural University at the Livestock Research Station, Thiruvazhamkunnu, in Palakkad district of Kerala. The objectives were to study the variation in bark thickness, heart wood content, specific gravity, fibre morphology, vessel morphology, and ray morphology between above species as well as to understand the radial variation within the trees under the prevailing agro climatic conditions. Results showed higher values for heart wood content, ray height, ray width, vessel frequency; and lower bark thickness in A. hirsutus, compared to the other two species while, P. marsupium had the highest air dry and oven dry specific gravity. A. heterophyllus had superior values for vessel diameter, vessel area, fibre length and fibre diameter. The information obtained from this study indicates the potential of these hitherto under-estimated multipurpose indigenous species for various end-uses. The results also points to the pertinent need to undertake long term tree improvement trials of the above species for efficient utilization of these promising species for the state of Kerala.

Comparative Wood Anatomy of Stem and Root in Korean-grown Yellow-poplar (Liriodendron tulipipfera L.)

This study was carried out to offer basic information on the wood anatomy of domestic yellow-poplar (Liriodendron tulipifera L.), a new plantation species selected by Korea Forest Service as one of the promising hardwood and bioenergy sources of the future, through comparison of stem wood with root wood in the qualitative and quantitative features. In the qualitative anatomical features, growth rings were distinct in stem wood but relatively less distinct in root wood. And stem wood appeared to have pores in radial multiples of 2 to 5, sometimes clusters but root wood to have pores in radial multiples of 2 to 3, rarely clusters. And numbers of bars in scalariform perforation plates were somewhat numerous in vessel elements of root wood than in those of stem wood. Interestingly, on the other hand, more extraneous materials in the wood rays of tap root than in those of lateral root and stem were confirmed in the chemical composition analyses. In the quantitative anatomical features, pore densities were significantly greater but vessel elements were considerably narrower in stem wood than in root wood. Vessel elements and wood fibers of root wood were considerably longer than those of stem wood. Rays were somewhat more numerous in stem wood than in root wood, and only ray heights of stem wood were more or less greater in cell numbers but both ray heights and widths of stem wood were lower in dimension than those of root wood. The anatomical differences between stem wood and root wood were thought to be associated with different growth environments between the stem above ground and the root below ground.

Prediction of transport properties of wood below the fiber saturation point – A multiscale homogenization approach and its experimental validation. Part II: Steady state moisture diffusion coefficient

In this publication a multiscale homogenization model for moisture transport in wood is developed and validated. The model aims at prediction of macroscopic transport properties of clear wood samples from their microstructure and the physical properties of a few microscale constituents. In the first part of this two-part paper, the theoretical background and fundamentals of the model were presented, and its specification for the estimation of macroscopic thermal conductivities was shown. In this second part the model is applied to steady state moisture diffusion below the fiber saturation point. The model starts on a scale of about 50 μm, where the wood cells form a honeycomb-like structure. In a first homogenization step the effective moisture transport behavior of the cell structure is determined from moisture diffusion properties of the cell walls and the (moist) air in lumens, respectively. Further homogenization steps account for the larger vessels that exist in hardwood species, the annual rings which are a succession of layers with different densities, and finally wood rays, that form pathways in the radial direction throughout the stem. The model validation rests on experiments as in the case of heat conduction: The macroscopic diffusion coefficients predicted by the multiscale homogenization model for tissue-specific composition data (input data set II) are compared to corresponding experimentally determined tissue-specific diffusion coefficients under steady state conditions (experimental data set). As for thermal conductivity, the good agreement of model predictions and test data underlines the suitability of the presented multiscale model.

Study on Wood Carbon Sequestration Based on Micro-Characteristics of Wood

Trees are complicated and important organisms in forest ecosystem. They are both carbon stocks and carbon source. In order to give full play to the role of wood carbon sequestration, this paper discussed the relationship of wood structural features and wood carbon sequestration at micro-level. It shows that wood carbon sequestration can be synthetically reflected by vessel, tracheid/xylon, wood rays, intercellular canal, xylem parenchyma and so on. The rate of cell wall and wood carbon sequestration is the relationship of direct proportional function. Micro-structural characteristics of wood can reflect wood carbon sequestration of forest ecosystems, as well as have a practical guide to enhance carbon storage of wood.

Multiscale homogenization of wood transport properties: Diffusion coefficients for steady-state moisture transport

This paper describes a multiscale homogenization model for macroscopic diffusion properties of wood. After a short introduction the physical background of steady-state diffusion processes in wood will be highlighted, resulting in a physically motivated macroscopic description of diffusion processes with only one diffusion equation and thus one diffusion tensor. This macroscopic diffusion tensor is derived by revisiting the morphological structure of wood in the framework of continuum micromechanics. The starting point is the cellular structure of wood; further homogenization steps include wood rays and the succession of annual rings. The quality of the model is assessed by a comparison of model predictions and measured values at different temperatures and moisture contents.

Study of the Influence of Anatomical Characteristics on Dyeing Effects of Plantation Pinus sylvestnis var. mongolica litv. Veneer

This paper takes plantation pinus sylvestnis var. mongolica litv. as study object, determines main anatomical factors influencing wood dyeing effects by measuring the related indexes of wood anatomical structure and dyeing effects, making a multiple regression analysis of them and analyzing the correlation variation law between wood anatomical structure and dyeing effects. The results show that there is a high correlation between pinus sylvestnis var. mongolica litv. dyeing effects and wood anatomical factors and the multiple correlation coefficients between anatomical factors and various dyeing effect indexes are between 0.573 and 0.786. The main anatomical factors influencing pinus sylvestnis var.mongolica litv.dyeing effects are tracheid proportion, wood ray proportion, resin canal proportion and late wood tracheid length, etc.

Pemanfaatan Kayu Manis (Cinnamomun burmanii) Berdiameter Kecil untuk Balok I-joist sebagai Bahan Konstruksi (Utilization of Small-Diameter Cinammon Logs for I-joist Beam as Construction Material)

Wood-processing industries currently face the limitation of large-diameter wood logs, due to their scarce stocks from natural forests. Wood from plantation forests can deserve consideration as an alternative raw material for those industries. However, plantation-forest woods are usually of small-diameter sizes and lower qualities compared to those of natural forest woods. One solution to deal with those problems is the conversion of plantation-forest woods into the reconstituted wood products, which can be arranged to various desirable sizes, and more beneficial for construction and other purposes. Hereby, the manufacturing of reconstituted wood products, called I-joist beam was tried from small-diameter plantation forest wood species, i.e. cinnamon wood (Cinnamomum burmanii). The assembling used phenol-resorcinol-formaldehyde adhesive. Mechanical properties of the I-joist beam with vertical-gluing profiles between laminae in the web portion were lower than those of the corresponding small-sized defect-free solid wood, but higher than those of I-joist with horizontal-gluing profiles between laminae in the web as well as the horizontally laminated beam made-up of cinnamon wood-laminae. The angle between wood ray and gluing line (plane) correlated negatively with the strengths of I-joist beam. These results indicated the positive prospect of manufacturing I-joist beam from small-diameter cinnamon wood for construction material.

“Ray-Intrusive” Laticifers in Species of Croton Section Cyclostigma (Euphorbiaceae)

A description of the occurrence and structure of “ray-intrusive” laticifers in the rays of species of Croton section Cyclostigma is provided. The systematic significance of laticifers within Croton section Cyclostigma is briefly discussed in relation to the section’s known production of red latex, commonly called “dragon’s blood”. A developmental hypothesis is offered and discussed in the context of the assumption that all laticifers in wood rays are non-articulated.

Green plastids, maximal PSII photochemical efficiency and starch content of inner stem tissues of three Mediterranean woody species during the year

Wood and pith of 1–2-year-old stems of three woody species with different life strategies common in the Mediterranean basin were studied during the year regarding (i) the occurrence of green plastids, (ii) their maximal photosystem II photochemical efficiency ( F v/ F m) and (iii) their starch content. Green plastids were identified from the red chlorophyll auto-fluorescence under epi-fluorescence microscope, F v/ F m was estimated using imaging-PAM fluorometry and starch content was recorded under bright field microscope after iodine staining. The evergreen sclerophyll Nerium oleander, the summer deciduous Euphorbia acanthothamnos and the winter deciduous species Platanus orientalis were selected for the study. Epi-fluorescence microscopy revealed that (i) all species possess abundant green plastids in their wood ray and pith cells throughout the year. In the winter deciduous species chlorophyll fluorescence was found to be strong during the leafless period. By contrast, in the evergreen and the summer deciduous species chlorophyll fluorescence was found uniformly bright during the year; (ii) F v/ F m value variation during the year seems to be species-specific: in the wood of N. oleander it remains unchanged whereas in the pith it is low during spring–summer; in both tissues of E. acanthothamnos F v/ F m value reaches maximal value during spring and in P. orientalis during autumn; (iii) in N. oleander and E. acanthothamnos starch is accumulated during spring, whereas in P. orientalis starch content is high during winter. The scanning electron microscopy (SEM) investigation revealed that the stem epidermis of all three species lacks stomata and formation of lenticels is delayed. Provided that gas exchange is therefore minimized and that PSII photochemical efficiency of inner stem tissues is relatively high, it is further supported that green plastids of wood ray and pith cells may help toward the re-fixation of the internally respired CO 2.

Possible causes for embolism repair in xylem

Wood sections of eight species of angiosperm and gymnosperm were made and observed under microscope. When a dehydrated section was rewet, the air inside its conduits contracted under the force of surface tension for several seconds to form elongated or spherical bubbles. The elongated bubbles in smaller conduits shortened till vanished. In addition, we also discorved that bubbles in larger conduits extended at first, then collapsed and disappeared; the bubbles outside conduits appeared gradualy or popped up in the field of view one after another; for some samples, they originated mainly from the cross sections of the wood rays. The smaller ones also collapsed and the larger ones grew up gradually. We suspected that air might transfer from the bubbles with short radii to those with large radii, both inside and outside conduits. The calculation of the amount of gas in all bubbles in a field of view supported our hypothesis. There are two possible mechanisms to explain the phenomena. First, based on the capillay equation, air can move from a smaller bubble to a larger one. Another reason is that the dissolving air from smaller bubbles can enter into the adjacent bubbles with larger curvature radii. Gas movement should obey the same rules in living plants. Therefore, we suggest that after cavitation events, instead of air moving from xylem into ambient atmosphere, two mechanisms could induce air to transfer from smaller conduits into larger conduits or the regions with lower pressures, leading the embolized conduits in the smaller conduits to repair. Furthermore, the differnce of values of contact angles in conduits might promote the refilling of embolism at lower xylem pressure.

Fracturing of wood under superimposed tension and torsion

A testing method using circumferentially notched round bars for investigating mixed mode behaviour under loading in tension and torsion is applied to wood. The applicability of the method to anisotropic materials is investigated for two types of wood, beech and spruce, considering the longitudinal and radial orientation with respect to the stem axis of the tree. The strong anisotropy of wood requires different evaluation procedures for radial and longitudinal sample orientation. The K-concept of linear elastic fracture mechanics (LEFM) and concepts of non-linear elastic fracture mechanics (NLEFM) were used for the evaluation of radial and longitudinal samples, respectively. Differences between the investigated wood types under radial orientation, in their durability to withstand torsional loads, could be observed by examining ratios of the values of the fracture toughness in mode III against mode I. Micrographs of the fracture surfaces support the assumption that the higher amount of wood rays in beech is responsible for the higher toughness under torsion. In case of longitudinal specimen geometry it was found that at very high levels of torsional deformation beech and spruce reach similar values in their specific fracture energy in mode I.