Stress-strain state of wood at kiln drying

Summary A model has been suggested which allows the calculation of stresses arising in kiln drying and humidification of wood, as well as the total residual strain, i.e. set strain _s, consisting of purely residual strain _r and the so-called frozen strain _f. Frozen strains arise under the operating influence of loading when the stiffness is increased because of a decrease in moisture content (or temperature) of the wood. The process of formation of set strains _s has been shown to depend on the history of loading, variations of the moisture content of the wood, as well as cooling of the section before the measurement of _s. The possibility of using set strain as a parameter of the state of stress of wood in kiln drying has been noted.Presented at the VIII. International Symposium on Fundamental Research of Wood. Warsaw, Poland, October 1990     

Study of the release in water of a chemical used for preservation of wood. Effect of the dimensions of the wood

Summary Various chemicals are used for protecting wood samples against fungi, and some of them are released in water, leading to pollution of the water. The kinetics of release of pentachlorophenol in water has here been studied, by considering the diffusion through the wood along the three principal axes of diffusion. The experiments and the modelling of the process is successfully coupled. The numerical model takes the three principal diffusivities, the partition factor, the volumes of wood and water into account. The effect of the length of the wood sample taken along the longitudinal axis of diffusion is especially studied, as the longitudinal diffusivity is much higher than the other two principal diffusivities. The effect of the relative volumes of wood and water is also of considerable interest not only for the concentration of the chemical in water but also for the rate of release.Symbols C concentration of liquid (g/cm³) - C_s, C_eq,t concentration of liquid on the surface, at equilibrium with the surrounding, respectively - C_i,j,k concentration of liquid in the wood at position (i, j, k) - D diffusivity (cm²/s) - h coefficient of mass transfer on the surface (cm/s) - i, j, k integers characterizing the position in the wood - K partition factor - L, R, T dimensions of the parallelepipedic wood sample - Mini amount of chemical contained in the wood at the beginning of the desorption - M_L, M_R, M_T dimensionless numbers - M_t, M amount of chemical released up to time t, up to infinite time, respectively - N half-number of slices taken in the wood parallelepiped along each dimension - V_water volume of the surrounding water - x, y, z coordinates - L, R, T thickness of the slices taken in the wood for calculation - t increment of time     

Vertikalbewegungen Rickettsiose-kranker Larven vonAmphimallon solstitiale (LINNAEUS),Anomala dubia aenea (DE GEER) undMaladera brunnea (LINNAEUS)(Col., Lamellicornia)

Zusammenfassung DurchRickettsiella melolonthae (Krieg) PHILIP infizierte Maikäfer-Engerlinge wandern während des Spätherbstes und Winters im Freiland absterbend auf die Erdoberfläche. Als Begleitarten inMelolontha Larvenpopulationen kamen im Gebiet vor:Amphimallon solstitiale (L.),Anomala dubia aenea (DeG.) undMaladera brunnea (L.). MitR. melolonthae künstlich infiziert, zeigten sie im Orientierungsversuch die gleiche Aufwanderungstendenz wie kranke Maikäferengerlinge, am deutlichsten die vonM. brunnea. Auf dem Waldboden fanden sich kranke Larven dieser Art in einigen Fällen.

---

Summary Larvae ofMelolontha spp. infested withRickettsiella melolonthae (Krieg) PHILIP move during October– January to the top of the soil where they eventually die. Larvae ofAmphimallon solstitiale (L.),Anomala dubia aenea (DeG.) andMaladera brunnea (L.) are susceptible forR. melolonthae, too. In experiments, artificially infested individuals showed a similar tendency to move upward. This was most pronounced inM. brunnea, of which some infested larvae were found on the forest floor.

---

Résumé Larves du hanneton, infectées parRickettsiella melolonthae (Krieg) PHILIP, se rendent à la surface de la terre au fin de l'automme et dans l'hivers. Comme espèces accompagnant les populations larvaires deMelolontha nous avons trouvés:Amphimallon solstitiale (L.),Anomala dubia aenea (DeG.) etMaladera brunnea (L.). Ils out démonstré, après une infection artificielle avecR. melolonthae, la mème tendence dans les essais d'orientation comme les vers blancs malades deMelolontha. Le phé nomène etait le plus prononcé parmi les larves deMaladera. De cette espèce nous avons trouvés plusieurs larves malades à la surface de la terre en plein champs.

---

Rickettsiella melolonthae (Krieg) Philip Melolontha- . . Melolontha- :Amphimallon solstitiale (L.),Anomala dubia aenea (De G.) Maladera brunnea (L.). R. melolonthae , Melolontha-, M. brunnea. .

     

Dimensional instability of cement bonded particleboard: Modelling CBPB as a composite of two materials

Previous papers have quantitatively indicated that the total movement of cement bonded particleboard (CBPB) is equal to the sum of the movement of its components. This paper examined the efficacy of the law of mixtures when applied to the movement of a wood-cement composite under internal swelling or shrinkage stresses. Abundant data generated in companion papers were first manipulated to develop the universal formulae for predicting the movement of components. In conjunction with previous numerical results from image analysis of the structure of CBPB, and the orientated elasticity and stress algorithms, the models for theoretically predicting mass and dimensional changes of CBPB were derived. Validation studies were conducted and these demonstrated an excellent agreement of the theoretical predictions with experimental data for both mass and dimensional changes of CBPB due to internal swelling or shrinkage stresses during adsorption and desorption. The success also implied that CBPB can be treated as a composite and its properties can be well derived by the law of mixtures even though CBPB is an unusual type of composite having a very high volume fraction of wood chips, but a very high mass fraction of cement paste.Notation E_RT Mean transverse modulus of elasticity of wood - E_L Longitudinal modulus of elasticity of wood - E_p Modulus of elasticity of cement paste - E_wa Modulus of elasticity of embedded wood chips at angle - E Modulus of elasticity of wood chips at direction - E Modulus of elasticity of wood chips at direction - G_LRT Mean transverse shear modulus of wood - L(T)_cp Length/width (thickness) change of CBPB at angle - L(T)_p Length (thickness) change of cement paste - m_pf Mass fraction of cement paste in unit mass of CBPB - m_wf Mass fraction of wood chips in unit mass of CBPB - M_cpj Mass change of CBPB at the various conditions tested - M_pj Mass change of cement paste at corresponding conditions - M_wj Mass change of wood chips at corresponding conditions - M(L; T)_w/P Mass, length or thickness changes of wood chips or cement paste at various conditions - t Duration of exposure - _LRT Mean transverse Poissons ratio of wood - V_pf Volume fraction of cement paste in unit mass of CBPB - V_wf Volume fraction of wood chip in unit mass of CBPB - _cp Density of CBPB - _k Density of wood chip or cement paste - _cp Overall stresses of CBPB at angle - _L Stress in the longitudinal direction of wood - _RT Mean stress in the transverse direction of wood - _p Stress of cement paste - _w Stress of the wood chips at angle - Stress of the wood chips at direction - Stress of the chip at direction - _cp Strain in CBPB - _p Strain of cement paste - _WL Strain in the length of wood chips - _WT Strain in the thickness of wood chips - _w Strain in wood chips - Angle between the longitudinal direction of wood chips and surfaces or edges of CBPB - Angle between wood chips and edges (length direction) of CBPB - Angle between wood chip and vertical coordinate - A, B, C Coefficients related to the feature of materials and exposure conditions The senior author wishes to thank Professor W.B. Banks of University of Wales, Bangor for his constructive discussions and assistance and the British Council for partly financial support.     

Die neuesten Erkenntnisse der forstlichen Entomologie in der Tschechoslowakei

Summary Present development of forestry entomology in the SSRThis article gives an outline on the occurrence of the more important harmful forest insects in the SSR in the year 1950–1962 and on the results of their study. The Norway spruce suffered from the year 1954 notably byIps typographus L. The control was based on insecticides, studies included optimal density of natural regeneration at the mass propagation etc. It was found, for instance, that typical density borings in bark (151–300 borings per 1 sq.m. of bark) shows variation in the shortest distance between borings from 54–70 mm. Relation between density of borings and their distance indicates function y = a.x^–b, (constant a = 476,9 and constant b= 0,38). It was further found thatIps typographus L. shows even sister generations twice in a year (about 60%, eventually even 30% females of the preceding population). Sister laying is conditioned mainly climatically, i.e. also by the forest stand elevation above sea level. A secure control of further harmful species of Norway spruce,Trypodendron lineatum (Ol.) was carried out by extirpation of wintering beetles in soil, eventually by treating of round wood by emulsions on the HCH + DDT basis.Cephaleia abietis L. shows two diapause periods in a larval stage. For this reason, the development of this species lasts prevailingly two years (90% population). Swarming imagines are controlled by chemical aerosols (10% DDT in the dosis 4–8 kg/ha). On obtained from eggsTrichogramma cephalciae Hochm. et Mart. which cannot be grown on eggs of butterflies. Investigations found that the clean eating ofZeiraphera diniana Guen. begins at the density of 300 caterpillars per one meter of long branch. Chemical control (aerosol 10 l/ha) is recommended when feeding is repeated for three years. The mass propagation ofBupalus piniarinus L. appeared on the Scotch pine. The critical number amounts 400 caterpillars per one kg of needles.Hylobius abletis L. is controlled by insecticides in trap barks and by underground traps for concentration of egg laying. Oak was injuried mostly by the rollerTortrix viridana. The critical number is one caterpillar per one bud. Other, in the SSR new harmful insect of oakArchips crataegana (Hb.) showed the critical number 100 egg heaps on the stem to the height of 2 m. The eggs of the above mentioned species showedTrichogramma embryophagum cacoeciae March., which can easily be grown on butterfly eggs. Oak 60–200 years old was attacked byApethymus biaccatus (Gmel.) andA. abdominalis (Lep.). Silver fir was harmed mainly by the rollerChoristoneura murinana (Hb.). Also the critical number was found. Egg rearing gaveTrichogramma minutum Ril. Ash indicates new type of bark injuries caused probably by a representative of the genusLestes (Fig. 1.). Poplars are damaged by the species of the familyCerambycidae, further byCryptorrhynchus lapathi L. and by the species of the familyAegeridae. Saperda carcharias L. has in the Czechoslovak conditions a generation of three years. Eggs overwinter.Cryptorrhynchus lapathi L. has in the southern Moravia mostly (70% population) one year generation, the rest shows a generation of two years. Beech and hornbeaum were harmfully attacked byErannis aurantiaria Hb.) andColotois pennaria (L.). It is obvious that in the year 1950–1962 several species (Alchips crataegana (Hb.),Apethymus braccatus (Gmel.),A. abdominalis (Lep.) on oak,Erannis aurantiaria (Hb.) andColotois pennaria (L.) on. hornbeam and oak,Pachynematus scutellatus Htg. on Norway spruce etc.) previously not known as important forest injurious insect, appeared as calamity species. Further it is obvious that some harmful insects probably under the influence of changed structure and also forest stand microclimate are retreating whereas other species show mass outbreak. For this reason it is necessary to study the lawfulness of the propagation of the individual species.

---

Résumé Les plus récentes expériences de l'entomologie en TchécoslovaquieLe travail contient un aperçu concernant la présence d'insectes nuisibles forestiers de certaine importance en Tchécoslovaquie au cours des années 1950–1962 ainsi que le résultat de leur recherche. Jusqu'à 1954 l'épicéa a été assaili surtout par l'Ips typogiaphus L. On cherche une solution de la défense au moyen des insecticides, la densité optimale d'attaque en cas de la reproduction excessive etc. Par exemple il a été constaté que lors de la densité typique de forage de l'écorce (151–300 forages par mètre carré d'écorce) leur distance ré ciproque varie de 54 à 70 mm. Le rapport entre la densité de forage et de leurs distances présente la forme de fonction y = a.x^–b, où la constante a = 476,9 et la constante b = 0,38. Ensuite il a été constaté qu'en ce qui concerne l'Ips typogiaphus L. existent même deux gé nérations-soeurs au cours de l'année (environ 60 % respectivement encore 30 % des femelles de la population pécédente). La production de pondaisonsoeur est soumis surtout au facteurs climatiques, c'est à dire même á l'altitude des peuplements. Contre un antre parasite de l'épicéa, leTrypodendron lineatum (Ol.), une certaine défense fut élaborée par l'extermination d'imagos hivernant dans le sol ou par le traitement de rondin par des émulsions sur la base HCH + DDT. En ce qui conceme laCephaleia abietis L. on a constaté deux phases de diapause en état de larve. C'est pourquoi le développement duparasite est en majorité biennal (90% de la population). II a été introduit une lutte chimique contre l'essaimage d'imagos par des aerosols (10% de DDT dans une dose de 4 à 8 kg par ha). On a réussi à faire sortir des oeufs de laTrichogramma cephalciae Hochm. et Mart. que l'on ne peut pas cultiver sur les oeufs de papillons. En ce qui concerne laZeiraphera diniana Guen. il fut constaté que la défoliation compléte a lieu par 300 chenilles sur une branche d'un métre de longueur. La lutte chimique est recommandée en cas d'attaque repétée au cours de trois ans. Sur des pins il fut constaté la multiplication de masse duBupalus piniarius L. où le chiffre critique et atteint par 400 chenilles sur un kg d'aiguilles. En ce qui concerne l'Hylobius abietis L. on élabora une manière de défense en utilisant des insecticides dans des pièges d'écorce et des pièges souterrains pour saisir les pondaisons. Sur le chêne c'était laTortrix viridana qui a causé les plus grands dé gâts. Le chiffre critique est exprimé par une chenille pour un bourgeon. En ce qui concerne l'ulté rieur parasite de chêne nouvellement apparu en Tchécoslovaquie, l'Archips crataegana (Hb.), le chiffre critique fut fixé par 100 agglomérations ovulaires sur le tronc jusqu'à 2 mètres de hauteur. On a obtenu laTrichogramma embryophagum cacoeciae March., qui peut être facilement cultivée sur les oeufs de papillons. Sur les chênes d'un âge de 60 à 200 sont apparus ensuite comme parasite desApethymus braccatus (Gmel.) et desApethymus abdominalis (Lep.). Sur le sapin apparaît surtout laChoristoneura murinana (Hb.). Un chiffre critique fut fixé. On a obtenu à partir des oeufs laTrichogramma minutum Ril. On a découvert sur le frêne un nouveau type de lésion de l'é corce provoqué vraisemblablement par la libellule g.Lestes (Fig. 1). Les capricornes, leCryptorrhynchus et lesSesia spp. sont nuisibles aux peupliers. En Tchécoslovaquie laSaperda carcharias L. a une géneration triennale. Les oeufs hivernent. LeCryptorrhynchus lapathi L. a en Moravie du Sud en majorité (70% de la population) une génération annuelle, le restant, biennale. Ensuite sur le hêtre et sur le charme a eu lieu l'apparition désastreuse de la chenille arpenteuseErannis aurantiaria (Hb.) et de laColotois pennaria (L.). Il en ressort donc qu'au cours des années 1950–52 plusieurs espèces ont fait une apparition désastreuse:Archips crataegana (Hb.),Apethymus biaccatus (Gmel.),Apethymus abdominalis (Lep.) sur le chêne,Erannis aurantiaria (Hb.) etColotois pennaria (L.) sur le charme et le hêtre, lePachynematus scutellatus Htg. sur l'épicéa et d'autres qui é taíent auparavent inconnus comme parasites considérables de la forêt.On peut en déduire qu'évidemment sous l'influence de la structure transformée et par consé quent du microclima des peuplements, certains parasites tendent à disparaître, tandis que d'autres insectes deviennent parasites désastreux. C'est pourquoi une recherche approfondie des lois de la reproduction en masse des différentes espèces est nécéssaire.

---

- 1950–1962. . 1954. Ips typographus L. , , . . , (151–300 1 ² ) 54 70 . y = a x^–b, a = 476,9 b = 0,38. , Ips typographus L. ( 60%, 30% ). , . . . Trypodendron lineatum (01.) , HCH + DDT. Cephalia abietis (L.) , (90% ). (10% 4–8 (). Trichogramma cephalciae Hochhm. & Mart., . Zeiraphera diniana Guen. 300 1 . . . ( 10 /) . Bupalus piniarius L., 1 400 . Hylobius abietis L. . Tortrix viridana L. 1 1 . , ,Archips crataegana (Hb.) 100 2 . Trichogramma embryophagum cacoeciae March., . 60–200 Apethymus braccatus (Gmel.) Apethymus abdominalis (Lep.). Choristoneura murinana (Hb.). . Trichogramma minutum Ril. - Lestes (. 1). , .Saperda carcharias L. . .Cryptorrhynchus lapathi L. (70% ) , . Erannis aurantiaria (Hb.) Colotois pennaria (L.). , 1950–1962. (Archips crataegana (Hb.),Apethymus braccatus (Gmel.),Apethymus abdominalis (Lep.), Erannis aurantiaria (Hb.) Colotois pennaria (L.), Pachynematus scutellatus Htg. . .), . , , . .

---

---

Herrn Prof. Dipl.-Ing. Dr. A. Pfeffer zum 60. Geburtstag gewidmet.     

Mangrove forest productivity and biomass accumulation in Hinchinbrook Channel,Australia

Data on stand structure and rates of photosynthesis were used to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests in Hinchinbrook Channel, Australia. Total annual canopy net carbon fixation was estimated to be about 29tCha–1yr–1. This equates to about 204,000tCyr–1 for all mangrove forests in Hinchinbrook Channel. Of this, only about 12% was stored as living plant biomass. Although it is not yet possible to present a robust carbon balance for mangrove trees, the remainder is presumably lost through plant respiration, litter fall, root turnover and exudation of organic compounds from roots.     

Studies on opposite wood in conifers part II: Histology and ultrastructure

Summary A study has been made of the histology and ultrastructure of opposite wood in Larix laricina, Picea rubens, and Pinus resinosa. The width of the growth rings varied considerably, in one case from 0.1–1.0 mm, with the wide rings containing a much higher proportion of latewood than the narrow ones. The earlywood tracheids were square in outline and more regularly arranged than in normal wood. In the latewood they were sometimes irregular and distorted. The S₃ layer in the tracheids was 0.2 m thick in the earlywood and 0.4–0.8 m in the latewood, as compared to a thickness in normal wood of 0.1–0.2 m in both zones. The S₃ was often buckled in the latewood and was terminated towards the lumen by a spiral thickening. The cell wall structure of the tracheid pit border was described. Normal coniferous wood might be regarded as an intermediate between opposite wood and compression wood.This paper is dedicated to Dean Edwin C. Jahn in honor of his 70th birthday.     

Fracture characteristics of PARALLAM® PSL in comparison to solid wood and particleboard

Summary Typical fracture characteristic values like load-displacement curve and specific fracture energy of the new wood laminate compound PARALLAM® PSL were determined by using the wedge splitting technique. Comparison with the values of solid wood and particleboard showed the superiority of this wood composite in both weak transverse orientations. This result is explained by the favourably oriented wood strands in PARALLAM® PSL with a length up to 2.6 m, which give rise to crack arresting mechanisms. In addition the influence of specimen geometry on the critical load and corresponding loadpoint-displacement at crack initiation was calculated for both isotropic and orthotropic materials using linear elastic FE-models.The authors thank Trus Joist McMillan for supplying the testing material and especially Dir. Donald Sharp for his helpful cooperation. Financial support by the Austrian National Bank (project no. 4917) is gratefully acknowledged.     

Die Stubenfliege lä043-01043-01043-01t sich ausrotten

Ohne ZusammenfassungDer Originalaufsaß erschien unter dem Titel The house Fly can be eradicated in The Southern Planter im Mai 1948 in Richmond (Virginia, USA.).     

Adsorption capacities and related characteristics of wood charcoals carbonized using a one-step or two-step process

Sugi (Cryptomeria japonlca D. Don) wood powder was carbonized at varying temperatures by a onestep process up to 1000C and a two-step process using wood charcoal as the raw material up to 1600C. This study was conducted to evaluate the adsorptive properties of wood charcoal and discuss the mechanism of its adsorptive function in relation to the physical and anatomical characteristics of wood after carbonization. Anatomical characteristics of carbonized wood materials were directly observed under heating using an environmental scanning electron microscope (ESEM); the cell wall structures were analyzed by high-resolution transmission electron microscope (HRTEM). The largest weight losses were observed at the highest temperatures, in both the one-step and twostep processes but leveled off above 800C. Shrinkages in the tangential, radial, and longitudinal directions increased with carbonization temperature, peaking at 1000C. Direct observations by ESEM showed distinct shrinkage at around 400C. The first trial observations by HRTEM on the changes in the ultrastructure of cell walls of wood charcoals were done, and it was assumed to affect the formation of micropores. Adsorption was found to follow the Langmuir isotherm model. With the one-step carbonization process, the iodine adsorption capacities of the carbonized wood powders increased with increasing carbonization temperature, peaking at 800C, but decreased at higher temperatures. The wood powder carbonized at 1000C with the two-step process showed the highest capacity, but further heating up to 1400C drastically decreased the adsorption. The shrinkage of cells was related to the increases and decreases in its specific surface area. Specific surface area and total pore volume were evidently related to the adsorptive properties.Part of this paper was presented at the Second International Wood Science Seminar, Indonesia, November 6–7, 1998     

Changes in the physical and chemical properties of six Japanese softwoods caused by lengthy smoke-heating treatment

The effects of prolonged smoke-heating treatments on wood quality were investigated. Six Japanese softwoods were smoke-heated for 100 and 200h at a temperature of 75° ± 5°C, which was recorded inside the log. After smoke heating, wood quality, including moisture content, amounts of chemical components, relative degree of crystallinity (RDC) of cellulose, and sapwood color were examined. Moisture content decreased as a result of smoke heating, especially in sapwood, leading to a uniform distribution of moisture content within a log. Almost no difference was found in the amounts of chemical components between the control woods and the woods that were smoke-heated for 100h. However, in the wood that was smoke-heated for 200h, the amounts of holocellulose decreased, suggesting that thermal deterioration and/or degradation of hemicelluloses had occurred. We assume that the increase in RDC was caused by smoke heating with the crystallization of cellulose and/or thermal degradation of hemicelluloses. Almost no differences were found in sapwood color between the control woods and the woods that were smoke-heated for 100h. In the wood that was smoke-heated for 200h, however, L*decreased, whereas a* and b* increased. As a result, E*ab, showing the total color change, increased, resulting in a deeper color. These results suggest that thermal degradation of hemicelluloses was caused by smoke heating for over 100h. Therefore, smoke heating of softwood logs using a commercial-scale kiln should not exceed 100h.     

Isolation of a β-1,3-glucan (laricinan) from compression wood of Larix laricina

Summary A -d-(13)-linked glucan has been isolated from compression wood of tamarack [Larix laricina (Du Roi) K. Koch]. The polysaccharide, which had []_D + 17.6°, consumed 0.17 mole of periodate per glucose residue and gave a methyl derivative which consisted of 115 2,4,6-tri- and 2,3,4,6-tetra-O-methyl-d-glucose residues in a ratio of 17.8:1. Partial acid hydrolysis yielded a series of -d-(13)-linked oligosaccharides, while enzymic hydrolysis with a -1,3-glucanase afforded glucose, laminaribiose, and laminaritriose. The glucan occurred in amounts varying from 2 to 4% in compression wood of this and other conifer species and was present in the wall of both tracheids and ray cells. It is proposed that this structural polysaccharide be designated as laricinan to distinguish it from callose and the various -1,3-glucans in lower plants.     

Collapse phenomena in beechwood during and after NH3-impregnation

Summary When beechwood is brought into contact with anhydrous ammonia, it swells like in contact with water. Upon removal of the ammonia from the wood, shrinkage is twice as high as before the treatment. Subsequent watering and drying still increase the linear shrinkage of beechwood. In order to find out in which dimensional range there is a reduction of volume in the wood, swelling and shrinkage tests as well as microscopic observations, mercury porosimetry measurements, and density measurements were carried out. The experiments showed that the collapse of the beechwood samples after ammonia treatment is caused by a reduction of the volume of the cell lumina and the perforations of the cell wall. With increasing duration of treatment, first the cell lumina, then the small and smallest pores of the cell walls are partly closed or even eliminated. However, this collapse does not extend to the molecular range. Density measurements even indicate a loosening of the substance during the first hour of ammonia treatment. With increasing duration of treatment, however, this loosening of the substance disappears again.The changes in the wood caused by ammonia treatment are so substantial that-analogous to ammonia cellulose-the term ammonia wood may be applied.This investigation was sponsored by the Zentenarfonds of the Swiss Federal Institute of Technology. The support of this research work is gratefully acknowledged. This article represents a part of the habilitation thesis submitted by the author to the Swiss Fed. Inst. of Technology with the title Physikalische und physikalisch-chemische Änderungen im Holz während und nach NH₃-Behandlung.     

Characterization of cellulose in compression and opposite woods of a Pinus densiflora tree grown under the influence of strong wind

Summary Structural factors in a Pinus densiflora tree grown under the influence of strong wind were measured. No difference for cellulose molecules was noticed between compression and opposite wood, but the was somewhat lower in the region where the compression wood was concentrated. The degree of crystallinity of cellulose was 45–50% in compression wood, about 50% in normal wood, and 50–60% in opposite wood. The crystallinity decreased with increasing height above the ground. The maximum point of crystallographic b-axis (fiber axis) orientation distribution for cellulose crystallites in compression wood was located at 30°, in normal wood at 25° and in opposite wood at 0°. The cellulose crystallite dimension in the transverse direction was 3.2 nm, corresponding to four cellulose unit cells, a value that was almost constant throughout the wood. In the longitudinal direction, there were large differences in cellulose crystallite dimensions between compression and opposite woods. In compression wood the cellulose crystallite dimensions was 12 nm corresponding to 11–12 cellulose unit cells. In opposite wood it was 17–32.5 nm corresponding to 17–32 cellulose unit cells. These structural factors were apparently affected by the environmental conditions, and the mechanical properties of the wood were influenced by these factors. Opposite wood had longer crystallites, a higher degree of crystallinity and a better orientation distribution of cellulose crystallites in the longitudinal direction. Compression wood, on the other hand, had shorter crystallites, a lower degree of crystallinity and a large angle between the stem and the direction of the crystallites.     

Über das Auftreten von Erdbeervirosen in Südspanien

Zusammenfassung In den Erdbeeranlagen der Sorte Tioga wurden mittels Blattpfropfung aufFragaria vesca alpina zwei Virosen ermittelt, die auf Grund der Symptome dem strawberry mottle = Erdbeervirus 1 zuzuordnen sind.Der Virusbefall des Ausgangspflanzgutes lag zwischen 4,1 bis 8,2 %, Er stieg im Anbaugebiet unter dem Einfluß einer intensiven Besiedlung durchPentatrichopus fragaefolii innerhalb eines Jahres von 65,2 % bis 69,6 %.Über den Test von Mutterpflanzen konnten inzwischen mehr als tausend virusfreie Stammpflanzen selektiert bzw. vermehrt werden. Die blattlausfreie Vermehrungslage in der Sierra Nevada ermöglicht die Fortfuhrüng einer virusfreien Erhaltungszucht.Die Ansteckungsrate kann in den Ertragsanlagen auf der Grundlage gezielter Blattlausbekämpfungen im Oktober/November sowie im Januar bis März erheblich gesenkt und damit praktisch bedeutungslos werden.

---

Summary Studies on viroses of strawberries in southern Spain After grafting strawberries of the sort Tioga uponFragaria vesca alpina two kinds of viroses belonging to the strawberry mottle group were observed. The primary attack amounted to 4.1–8,2%. Under the influence of the aphidPentatrichopus fragaefolii the attack rises to 65.2–69.6 %.More than thousand healthy plants were selected and multiplied. By this a plantation of healthy strawberries was settled in Sierra Nevada. Controlling measures against aphids in October/November as well as in January/March prevent the virus from enlarging on the plantation anew.

     

Influence of moisture content on the vibrational properties of hematoxylin-impregnated wood

The vibrational property of hematoxylinimpregnated wood was investigated from the aspect of moisture content dependence. The specific dynamic Young's modulus (E/) and loss tangent (tan) of hematoxylin-impregnated wood were determined in the relative humidity (RH) range of 0%–97%, and were compared with those of the untreated and some conventional chemically treated woods. The changes in theE/ and tan of wood with increasing RH were suppressed by acetylation and formaldehyde treatment because of a marked reduction in the hygroscopicity of the wood. Although the hematoxylin impregnation did not significantly affect the hygroscopicity of the wood, its influence onE/ and tan were similar to that of formaldehyde treatment at low RH and of acetylation at medium RH. It was supposed that at low to medium RH hematoxylin restrains the molecular motion of amorphous substances in the cell wall because of its bulkiness and rigidity. On the other hand, at high RH it seems to work as a plasticizer with adsorbed water molecules.     

Ultrastructure—Critical domain for wood behavior

Summary That the behavior of wood in service results from its structure is generally accepted by wood scientists. No doubt this acceptance is due to the broad interpretation of such a term. Structure can refer to the organization of elements on a macro scale, such as in a laminated beam, as well as to the arrangement of cellulose molecules in the crystalline region of an elementary fibril.This presentation focuses on a structural domain that appears increasingly to be a critical one in wood behavior-ultrastructure. The spectrum of terminology that has been used in profusion during the electron microscopic era must first be defined so that confusion is minimized. Then a historical evolution of the field of wood ultrastructure can be presented to provide perspective. Structures that have been shown to affect or indeed to control certain processes can be identified. The role of a non-structure, the elusive transient capillary, can be illustrated. Microfibrillar organization and cell wall archictecture fall into the realm of ultrastructure as well.The past decade of research in wood science has been productive to a significant extent because of scanning electron microscopy and its accessory tools and techniques. The exploration of wood penetration by wood preservatives, pulping liquors and coatings using this approach has yielded much new evidence. One can speculate about the anticipated contributions of computer-driven SEM, stereology, STEM, and even higher resolution microscopy in the near future.     

The thermodynamics of sorption with reference to klinki pine

Summary An investigation into the bonding energy relationships for water in wood indicates that as the temperature increases at constant total moisture content, water moves from within the chemical structure to the adsorption surface. The analysis is evaluated for the wood Araucaria klinkii Lauterb and it is indicated that at 25 °C, less water is held in the chemical structure during adsorption than during desorption.Symbols A amplitude of liquid surface profile - A₀ amplitude of solid surface profile - a mean radius of curvature of liquid surface (bubble radius), Å - a₀ mean radius of curvature of solid surface, Å - a_c a constant value of a, Å - F a function of temperature - f capisorption energy fraction - G a function of - g specific Gibbs free energy of saturated water vapour relative to unsaturated water vapour at the same temperature, J/kg - g_c specific Gibbs free energy associated with capisorption, J/kg - g_p specific Gibbs free energy associated with physisorption, J/kg - h change in specific enthalpy of liquid water as it is desorbed, J/kg - l latent heat of vaporisation of free water, J/kg - m wave number/m - p_s pressure of water vapour at saturation, Pa - R specific gas constant for water vapour, J/kg K - r relative humidity - s change in specific entropy of liquid water as it is desorbed, J/kg K - T temperature, K - w dry basis moisture content - x ln p_s/p_s25 - y In r - z length coordinate, m - , , constant coefficients - change in mean height of liquid surface, Å - ₀ a constant length, Å - constant - distance from solid to liquid vapour interface measured normal to solid surface, Å - ₀ a constant value of , Å     

Exact analysis of shear strain in wood

Summary An analysis is given which enables the shear strain in a piece of timber to be specified in terms of the difference between tangential and radial strain, herein termed the angular strain. The angular strain is then evaluated in terms of the orientation of two lines at right angles prior to deformation. The equations involved are simple and facilitate the evaluation of strain parameters which would otherwise require numerical computation.Symbols a, b, c length parameters, Fig. 2 - C half chord length - k constant of proportionality - r radial coordinate (distance from pith) - x length coordinate (board) - , angle parameters, Fig. 1 - shear strain - width of segment - angular strain - #x025B; tangential strain - _r radial strain - ₁, ₂ components of shear strain, Fig. 1 - angle parameter, Fig. 2 - angle parameter, Fig. 3 - angle parameter, Fig. 2 The author wishes to thank Mr. J. W. Sutherland for his assistance with the presentation of this paper.     

Electromagnetic shielding efficiency of the electric field of charcoal from six wood species

Six wood species were carbonized under various carbonization temperatures and nonoxygen conditions to obtained charcoal. The effects of wood species, rate of temperature rise, and carbonization temperature on the electromagnetic shielding efficiency (ESE) of the electric field were investigated. The wood species used in this study were Japanese cedar, China fir, western hemlock, red oak, fortune paulownia, and Taiwan acacia. Tested materials were carbonized in a high-temperature oven under the following conditions: rate of temperature rise 1°–5°C/min; carbonization temperature 500°–1100°C, with temperature intervals of 100°C; maximum temperature maintained for 1h; and flow rate of nitrogen 300ml/min. The electromagnetic insulation strength system was used to detect the ESE of the electric field of charcoal. It was found that western hemlock and fortune paulownia charcoal showed maximum ESE values of of 36 and 61dB generated at a carbonization temperature of 1000°C. The charcoals derived from four other wood species showed maximum ESE values of 28dB for Japanese cedar, 23dB for China fir, 32dB for red oak, and 38dB for Taiwan acacia, respectively, at a carbonization temperature of 1100°C. The ESE value for fortune paulownia charcoal was similar to those of metal nets. The relations between ESE and logarithmic values of resistivity (log) could be represented by a negatively exponential formula.Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000