Shear creep and mechanosorptive behavior of nail-plate-jointed laminated-veneer lumber

The objective of this research was to evaluate the mechanosorptive deflection of shear creep of nail-plate-jointed laminated-veneer lumber. The joint was composed of steel gusset and nails, 40 mm in length and 2.8 mm in diameter (Zn40). The specimens were loaded parallel (PA) and perpendicular (PE) to the grain. Shearing loads applied were 50 and 100kgf, and the load levels were 11% and 22% (PA) and 7% and 14% (PE) of the maximum strength obtained from static testing. The creep test specimens were loaded for 1500h. A few general conclusions could be drawn from this study: The mechanosorptive deflection (_ms) is defined as _ms = _t — (_c + _sh) — _o, where _t, is total deflection, _c is pure creep, _sh is shrinkage-swelling behavior, and _o is the initial deflection. Changes in relative humidity may cause more severe creep deflection than constant humidity, especially during the drying process. The mechanosorptive deflection is greater at the lower load level than that at the higher load level. The mechanosorptive effects seem to be somewhat more resistant in the parallel direction than in the perpendicular direction.     

Stress distributions and failure types of curved laminated veneer lumber for use in furniture under loading

To control reliably the suitable use of curved laminated veneer lumber (LVL) as a structural member of furniture, stress distributions and failure types of curved LVL made from massion pine (Pinus massoniana Lamb.) and fast-growing poplar (Populus euramericana CV. I.) were investigated under end-pull, end-thrust, and transverse loading. The results are summarized as follows: In curved LVL of two wood species, absolute values of the maximum axial stress ( _A) occurring at the convex surface are smaller than those ( _B) that occurred at the concave surface. The differences between these values decrease with an increase in the radius of curvature. With end-pull loading, there were mainly splitting failures at glue lines near the centroidal axis. With end-thrust loading, there were more fibrous fractures on the tensile side and crushing failures on the compression side. With transverse loading, curved specimens of massion pine exhibited mainly splitting failures. In contrast, for curved LVL of fast-growing poplar, fibrous fractures occurred mainly on the tensile side. Absolute values of _A and _B significantly increased with an increase in the radius of curvature. In contrast, absolute values of the maximum radial stress ( _R,) decreased with an increase in the radius of curvature. Absolute values of _A, _B, and _R of curved LVL of massion pine were larger under end-thrust loading than under end-pull and transverse loading. Conversely, absolute values of _A and _B of curved LVL of fast-growing poplar were small under end-thrust loading. However, absolute values of _A and _B of curved LVL of two wood species under end-pull loading were almost similar to those under transverse loading.Part of this study was presented at the 10th annual meeting of Chugoku Shikoku branch of the Japan Wood Research Society, Miki, Kagawa, September 25, 1998 and the 4th Pacific Rim Bio-Based Composites Symposium, Bogor, Indonesia, November 2–5, 1998     

Prediction of the buckling stress of intermediate wooden columns using the secant modulus

We made several buckling tests of wooden columns with intermediate slenderness ratios () and examined the empirical formulas. On the basis of the examination, we formulated an equation for predicting the buckling stress () of an intermediate wooden column. Sitka spruce (Picea sitchensis Carr.) and buna (Japanese beech, Fagus crenata BI.) were used for the studies. A compressive load was applied on the specimen supported with pin ends, and the buckling stress was predicted by the tangent modulus theory and two empirical equations: those of Tetmajer and Newlin-Gahagan. The predicted - relations were compared with the test results, and the applicability of these predictions were examined. Based on the comparisons, we formulated an equation that can predict the - relations of materials with various stress-strain characters in the plastic strain range.     

Methods to estimate the length effect on tensile strength parallel to the grain in Japanese larch

To find a desirable method for estimating the length effect on tensile strength ( _t), we used three methods to analyze the _t data from a Japanese larch (Larix kaempferi) small, clear specimen. These methods included a nonparametric method, the projection method of Hayashi, and a proposed method. The estimated length effect parameters (g) by the nonparametric method were 0.0237 and 0.0626 for 50th and 5th percentile _t distributions, respectively. The projection method requires a standardE _f level (E ^*: dynamic Young's modulus), arbitrarily chosen for calculating theg value. Theg values from the projection method were 0.1122 for lowE ^*, 0.0898 for averageE ^*, and 0.0759 for highE ^*. The estimatedg values by the proposed method using selected _t data were 0.1020 and 0.1838 for the 50th and 5th percentiles, respectively. Among the three methods, the nonparametric method did not consider the different distribution of Young's modulus among specimens, and the estimated length effect parameters (g) by this method were small. The projection method reduced the influence of Young's modulus, but the length effect parameters varied with theE ^* level. The proposed method minimized the dependence onE _f distributions among specimens. we believe the latter method is desirable for estimating the length effect on tensile strength.     

Modelling the long-term strength of timber columns

Summary This paper studies the influence of the used creep function, and the duration of the experimental sustained loading from which the creep function was derived, in modelling the long-term buckling strength of timber columns. The sensitivity of this buckling strength to creep and initial deflection is numerically studied using an energy approach that takes into account the initial deflection. Various creep functions — power laws as well as exponential laws — derived from bending experiments of different durations are used for the numerical simulation. The crucial need for experimental results issued from very long load period experiments is identified. Such experiments may lead to a more credible creep analysis of timber structures.Symbols i radius of giration - s stress level - E_L effective MOE - E₀ instantaneous MOE - I inertia moment - K,K geometrical matrices - L length of beam or column - L_f effective length - N_cr axial force, buckling load - U elastic strain energy - W external forces work - t time variable - u moisture content (m.c.) - v total deflection - v_c, v_e, v₀ creep, instantaneous elastic and initial deflections respectively Greek Letters (t) time function - , _e, ₀ total, instantaneous and initial strains respectively - twist rotation - (t) creep coefficient or fractional creep or relative creep - (x) shape function - load factor - longitudinal shortening - total potential energy - creep factor - relaxation time     

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.     

Zum Auftreten einiger Laus- und Käferarfen an Jungkiefern

Summary Larvae ofErnobius spp. and adults ofBrachyderes incanus were serious pests of shoots ofPinus silvestris andP. contorta at several localities of Rhine valley and near Meppen/Ems.In the same areas aphids(Lachninae) and their predators were very abundant.Protolachnus agilis Kltb. became very harmful on young pines in experiment field cages where predators had been excluded.Pineus sp. was frequent in the field cages and in young pine plantations near Meppen.

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Résumé En divers endroits de la vallée du Rhin et près de Meppen/Emsland, des larves d'Ernobius spp. et des adultes deBrachydeles incanus furent observés comme étant de sérieux pour les jeunes pousses dePinus silvestris et deP. contorta.Dans les mêmes régions des pucerons(Lachninae) et leurs prédateurs étaient très abondants.Protolachnus agilis Kltb. divint très nuisible aux jeunes pins placés dans des cages expérimentales où les prédateurs avaient été enfermés.Pineus sp. é tait aussi abondant dans cages expérimentales et dans les plantations de jeunes pins près de Meppen.

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Meppen/Emsland Eronobius spp. Brachyderes incanus, Pinus silvestris P. contorta. (Lachninae) Protolachnus agilis Kltb. , - .Pineus sp. - Meppen.

     

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.

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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.

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- 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. . .), . , , . .

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

Generationszahl der RübenfliegePegomyia hyoscyami betae Curt.

Summary During the years 1959–1961 the number of generations was followed in Spinach Leaf Miner (Pegomyia hyoscyami betae Curt.) in central Bohemia at 310 m above sea level and in the year 1961 in southern Bohemia at 450 m. The larvae and the eggs were studied on the leaves at regular 10–14 days' intervals by controlling each plant and images by means of a sweeping method. There have been acertained two generations in the year 1959 and three generations in the year 1961 in central Bohemia and two generations in the year 1961 in southern Bohemia. The occurence of every generation of larvae on the suggar-beet was separate and the previous and the consecutive generation did not overlop.The origin of the erroneous date on 6–7 generations of this species (Rambousek, Neuwirth, 1931) has been also cleared up in this article. This statement has been taken over by Sorauer (1953) from the Review of Applied Entomology (1931) and has been lately mentioned by many authors. F. Neuwirth gave a personal information, that the statement on 6–7 generations occurence of Spinach Leaf Miner has been found on the basis of theoretical calculation (from the lenght of one generation in spring and not on the basis of the facts found in natural conditions).

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Résumé En 1959–1961 le nombre des générations de la mouche de la betterave a été observé dans la Bohème Centrale á l'altitude de 310 m audessus de la mer et en 1961 dans le Sud de la Bohème á l'altitude de 450 m. Les larves et les oeufs ont été observé sur les feuilles dans les intervalles de 10–14 jours regulierement effectués sur chaque plante et imagines en particulier par le filet fauchior. En 1959 deux générations et en 1960 et 1961 trios géné rations dans la Bohéme Centrale, ainsi que en 1961 deux générations dans le Sud de la Boheme ont été constates. La prence de chaque génération des larves sur la betterave aété separée et les générations consecutives ne malaient pas presque jamais avec les précedents.Dans cet travail l'auteur a clarifié comment une donnée fautive sur 6–7 générations de cette espéce est survenu (Rambousek et Neuwirth, 1931). Cette donnée orginante de Review of Applied Entomology [1931] a été reprise par Sorauer (1953) et elle a été ensuite récemment mentionée par d'autres auteurs. Selon une déclaration personelle de Mr. F. Neuwirth les donées des 6–7 générations de la mouche de la betterave en Tschécoslovaquie ent été acquis par une évaluation théoretique (se basant sur la durée de la génération du printemps et non sur les resultats des observations réelles dans les conditions naturelles.

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1959–61 . (310 . ) 1961 . (450 . ). 10–14 , . 1959 . 2 , 1960 . — 3, 1961 . — 2 . , . , 6–7 (Rambousek, Neuwirth 1931). . . 6–7 , , .

     

Richtungen der angewandten Entomologie in Bulgarien

Summary For protection of agricultural crops, archards, forests and stored products a system of institutes for vegetative protection have been gradually built in Bulgaria within the last fifteen years. Now a leading part in the study of pests and diseases of plants are taking the Academy of Rural Economy Sciences and the Institutes for Plant Protection, for Forest Protection, the Zoological Institute by the Bulgarian Academy of Science, the Higher Rural Economy Institute and the Higher Forest Institute. Specialists of all ranks are working at these institutes: academicians, member correspondents, professors, senior and junior scientific collaborators and a great number of experts and assistants. Parallel with the studies of specific composition of pestilent insects, their biology is being explored and experiments are being made with insecticides. An inquiry is also being undertaken for utilization biologic combat against noxious insects. In aid of scientific institutes a dense network of services for heading the research work and combat on the terrain has been organized.

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Résumé Pour la défense des cultures agricoles, des vergers, des forêts et des produits récoltés, un système d'instituts pour la défense végétale a été successivement dé veloppé en Bulgarie pendant les dernières quinze années. Actuellement l'Academie des sciences de l'economie rurale et les Instituts pour la défense végétale ont le rôle dirigeant dans les recherches de la nocivité et des maladies sur les plantes. Dans ces instituts travaillent des spécialistes de toutes les catégories scientifiques: des académiciens, des membres-correspondants, des professeurs, des travailleurs scientifiques supérieurs et plus jeunes, avec un grand nombre d'aides-spécialistes. Parallèllement à l'étude de composition specifique des insectes nuisibles on étudie sa biologie, de même on fait des expériences avec des insecticides. Aussi on cherche à utiliser la lutte biologique contre les insectes nuisibles. Pour faciliter les instituts scientifiques dans cette lutte et leur recherche sur le terrain, un immense service est organisé dans tous les plus grands emplacements peuplés du pays.

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Bearing properties of engineered wood products I: effects of dowel diameter and loading direction

The embedment tests of laminated veneer lumber (LVL) with two moduli of elasticity (MOE; 7.8 GPa and 9.8GPa), parallel strand lumber (PSL), and laminated strand lumber (LSL) were conducted in accordance with ASTM-D 5764. The load-embedment relation for each of these engineered wood products (EWPs) was established. The directional characteristics of bearing strength (_e), initial stiffness (k _e), and effective elastic foundation depth were obtained from the tested results. The effective elastic foundation depth (=E/k _e,E = MOE), based on the theory of a beam on elastic foundation, was obtained from thek _e and MOE. An of 90° (perpendicular to the grain) was calculated by dividingE ₉₀ [MOE of 90° from the compression test, but MOE of 0° (E ₀), parallel to the grain, obtained from the bending test] byk _e90, the initial stiffness of 90°. This study aimed to obtain the bearing characteristics of each EWP, taking into consideration their anisotropic structures, for estimating the fastening strength of a dowel-type fastener. The relations between the bearing coefficients ( _e,k _e,) on the loading direction and dowel diameter were established from the load-embedment curves. Based on the results of the embedment test, tested EWPs showed different tendencies in all directions from wood and glued laminated timber.Part of this study was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Effects of length of seed chilling period and sowing date on family performance and genetic variances of Douglas-fir seedlings in the nursery

Seeds of four full-sibling Douglas-fir families (F) were moist chilled (C) for 14, 33, and 77 days and sown (S) March 29, April 26, and May 24 at two densities (D=111 and 200 seeds/m²), grown for 2 years in nursery beds and phenology and size traits recorded. The study was analyzed in two parts: part I evaluated seed treatment effects and their interactions with families; and part II investigated the effect of treatments on genetic variances, particularly among-family (_F ²) and within-plot ( ²) components and the intraclass correlation for families (t_{% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaGqaa0Gaa8NKba% aa!3886!\[f\]}). In part I there were large and highly significant differences associated with C and S and among F for all traits. Early S combined with long C resulted in early emergence and gave large seedlings with little loss and damage. Many interactions between C and F, and S and F, were significant. Interactions involved rank changes for size but not for phenology traits, and were larger for C×F than for S×F. Seedling density affected seedling size but not phenology, did not interact with seed treatments, and interacted significantly but weakly with families. In part II, C and S, but not D, had significant effects on _F ², ², and t_{% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaGqaa0Gaa8NKba% aa!3886!\[f\]}, but not in a predictable manner. Because of significant interactions, it is recommended that standardized seed treatments be used in family nursery tests. This should aid in keeping the results from these tests as repeatable as possible. Long chilling and sowing as early as practicable are recommended to minimize disease losses and winter damages and to provide good nursery stock.     

5α-Reductase inhibitory component from leaves ofArtocarpus altilis

The inhibitory effects of 17 samples prepared from Thailand plants on 5-reductase activity were examined. The acetone extract of leaves ofArtocarpus altilis showed potent 5-reductase inhibitory activity. Fractionation guided by 5-reductase inhibition led to the isolation of 2-geranyl-2,3,4,4-tetrahydroxydihydrochalcone from the acetone extract of leaves ofA. altilis. This compound showed more potent inhibitory effect (IC₅₀=38M) than-linolenic acid known as a naturally occurring potent inhibitor.     

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.

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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.

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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.

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

     

Relationship between radial variations in shrinkage and drying defects of tree disks

This study was conducted to investigate the relationship between radial variations in shrinkage and drying behavior of larch disks during radio-frequency/vacuum (RF/V) drying. Despite considerable variations in shrinkage both within and between logs, some trends were observable for each log. Actual radial shrinkage was much larger than free radial shrinkage with a ratio of tangential shrinkage ( _T) to radial shrinkage ( _R) ranging from 1.27 to 1.62. If the _T/ _R ratio of larch was about 2.5, the relative displacement was theoretically estimated to be 1.6 to 1.65, showing good agreement with the experimental results. The results showed that the formation of V-cracking was closely related to the actual differential shrinkage, which is the difference between the estimated tangential shrinkage and actual radial shrinkage after drying.     

Linearity and non-linearity in mechano-sorptive creep of softwood in compression and bending

Summary Non-linearity of softwood in axial mechano-sorptive creep during moisture cycling can be characterised as departure from linear behaviour. Linear behaviour is shown by experimental measurement to be a gradual approach to a creep limit with exponentially decreasing increments of compliance, J_i, per moisture cycle, when tested under a constant stress. On the other hand, when the stress is progressively increased by a small increment after each moisture cycle, the compliance increments will progressively increase, having a value of , where n is the cycle number. By subtracting one compliance increment from the succeeding one, the value of J_i can be obtained. Analysis of experimental results in bending tension and compression showed that the compression test pieces departed from linearity at total strains around 0.14% to 0.15%, the bending test pieces showed slight evidence of non-linearity at about the same strain, whilst the tensile pieces were approximately linear up to 0.18% strain.This project was supported by the U.K. Science and Engineering Research Council and by the European Commission     

Traditional fallows in Latin America

Traditional fallow systems of Latin America have not been extensively studied from either a socioeconomic or biophysical viewpoint. Only in the past decade have some of these systems — modified shifting cultivation in the Amazon, the bracatinga (Mimosa scabrella) fallow of southeastern Brazil, the babassu (Attalea spp.) system of the Amazon margins, and short bush fallows mostly for Phaseolus bean (the so-called frijol tapado) — received any attention. Over the past century, traditional cultivators have adopted several legumes such as Mucuna spp., Lathyrus nigrivalis, Canavalia spp., and Senna guatemalensis as green manures or managed fallows in food crop production systems, which have recently been the object of studies by social and biological scientists. Longer, monospecific fallows involving woody legumes have been studied to varying degrees. The legumes include Senna guatemalensis, Mimosa tenuiflora, and Gliricidia sepium. Systems in which crop production is alternated with animal grazing of secondary vegetation include the caatinga of Northeast Brazil, the espinales of Chile, the matorrales of northern Mexico, and the chaco of Argentina, Paraguay, and Bolivia. A classification is proposed depending on the nature of the species (woody or nonwoody) and their composition (mono- or multispecies) and land management (burned or not). Much work is still needed in more complete characterization, determination of economic importance and potential, understanding the relationships among components, studies of nutrient cycling, and verification of the effects of shorter fallow periods of these systems.This revised version was published online in November 2005 with corrections to the Cover Date.     

Influence of knot area ratio on the bending strength of Canadian Douglas fir timber used in Japanese post and beam housing

A study was conducted to establish the engineering properties and the influence of knot area ratio (KAR)-based grading rules on the bending strength properties of full-size Canadian Douglas fir timber used in Japanese post and beam building construction. In-grade tests were conducted on lumber selected at random from coastal mills in British Columbia, Canada, that manufacture products for the Japanese post and beam housing market. Bending strength and modulus of elasticity test results and KAR-based out-turn information on the 105 × 105mm and 45 × 105mm specimens are presented in this article. The in-grade test results indicate that KAR-based grading rules can be successfully applied to Canadian Douglas fir timber to meet strength property requirements.     

Holzangriff durch Larven der AmpferblattwespeAmetastegia glabrata Fall.(Hym., Tenthredinidae)

Zusammenfassung Die Altlarven 2. Generation der AmpferblattwespeAmetastegia glabrata Fall. sind im Obstbau als Schädling bekannt. Die Schäden entstehen bei dem Versuch der Larven, in Früchten Puppenkammern anzulegen.Üblicherweise verpuppen sich die Larven in den trockenen Stengeln der Nährpflanzen(Polygonaceae) oder anderem trockenem oder verholzten Pflanzenmaterial.Es wird über einen gesicherten Fall berichtet, in demAmetastegia glabrata-Larven in verarbeitetem Nutzholz (Plakattafel) schädlich geworden sind. Ein weiterer Fall konnte nicht völlig geklärt werden; jedoch waren auch hier Blaltwespen-Larven in einer Wohnung in verarbeitetes Nutzholz (Türrahmen) eingedrungen.Nach dem geringen Umfang der Schäden, die nur durch die Anlage kurzer Puppenkammern in weichen Holzteilen entstehen, istAmetastegia glabrata in die Gruppe der gelegentlichen Holzzerstörer einzureihen. Allerdings kann durch diese Art völlig gesundes Holz im Freiland angegriffen werden.Holzschutzsalze vom U-Typ genügen zur Vorbeugung nicht. Vorbeugungs- und Bekämpfungsmaßnahmen werden besprochen.

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Summary Attack on wood by larvae of the dock sawfly Ametastegia glabiata Fall. (Hym., Tenthiedinidae) Normally the mature larvae of the last brood of the dock sawfly bore themselves for pupation into dry stems of plants.By the gnawing efforts in certain years of appearance in masses, however, they may attack fruit too, especially apples, and cause considerable damage by numerous gnawing spots.Besides these known injuries on fruitA. glabrata has now been stated in two cases as an occasionally dangerous animal to dry timber too.The damage caused is described by word and picture; preventive and curative measures are discussed.

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Résumé Attaque du bois par des larves de la Tenthrenidé Ametastegia glabrata Fall. (Hym., Tenthredinidae) Normalment les larves adultes de l'A. glabrata se forent dans les tiges sèches des plantes pour la mé tamorphose.Cependant aussi des fruits, surtout des pommes, sont attaqués par le ronger pendant les anées quand ces insectes paraîssent en masse. Des dommages considérables sont provoqués aux points d'attaque nombreux.A côté de ces dommages connus aux fruits l'A. glabrata a été constaté en deux cas comme causeur de dommage par occasion en bois sec de construction.Les dommages sont décrits et figurés; des methodes preventives et curatives sont discutées.

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? Ametastegia glabrata Fall. (Hym., Tenthredinidae) . , , , . Ametastegia glabrata Fall. ( ) . , .

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Mitteilung aus dem Holzschutzlaboratorium der Farbenfabriken Bayer AG., Werb Uerdingen     

Growth and wood quality of sugi (Cryptomeria japonica) planted in Akita prefecture (II). Juvenile/mature wood determination of aged trees

Variations of certain anatomical and mechanical indices within tree stems of aged sugi (Cryptomeria japonica) trees planted in Akita prefecture were studied. The determination of the juvenile/mature wood boundary was also discussed, and the effects of wood structure on mechanical properties were investigated. On the basis of radial and vertical variation of the anatomical and mechanical indices, modulus of elasticity (MOE)/ shear modulus (G) was chosen as the index for determining the juvenile/mature wood boundary. The increase rates of MOE/G at the points of 1%, 2%, and 3% were discussed. It was found that for aged trees, all three points were thought to be effective for dividing juvenile and mature wood. However, for younger trees, the point of 2% was recommended, which was mostly consistent with the result obtained by the increase rate of 1% for tracheid length (TL). Among mechanical properties, the MOE showed more significant juvenile/mature wood differences than did modulus of rupture (MOR) and . By correlation analysis, it was suggested that microfibril angle largely contributed to the indices of MOE and G, and specific gravity largely contributed to the indices of MOR and .Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003