scholarly journals Evaluation of Bent Trees in Juvenile Teak (Tectona grandis L.f.) Plantations in Costa Rica: Effects on Tree Morphology and Wood Properties

2017 ◽  
Author(s):  
Nancy Guzmán ◽  
Róger Moya ◽  
Olmán Murillo
Keyword(s):  
Costa Rica ◽  
Modulus Of Elasticity ◽  
Morphological Characteristics ◽  
Tectona Grandis ◽  
Wood Properties ◽  
Early Years ◽  
Chemical Compositions ◽  
Variable Diameter ◽  
Morphological Variables ◽  
The Relationship

Bent trees have been observed during the early years in juvenile plantations (less than 5 years-old) of Tectona grandis in Costa Rica. The relationship between bending and the morphological characteristics of the trees was explored. An evaluation of bent trees was conducted in six juvenile plantations (8, 17, 27, 28, 31, and 54 months old) of Tectona grandis. Site 1 with 8-month-old plantations did not display any relationship with any tree morphological variable (diameter, height, and crown weight of tree), whereas for the sites 2, 3, and 4 with 17-, 27-, and 28-month-old plantations, respectively, all the tree morphological variables were statistically correlated with the bent trees. A multiple regression analysis showed that the most influential variables were height to crown base, crown weight, diameter, and total height of the tree. An evaluation of the bending risk factor (RF) was correlated with the height to crown base, crown weight, and form factor. The modulus of elasticity and chemical compositions of bent trees differed from those of straight trees. The causes of tree bending are complex, involving, among other factors, the morphology of the trees, plantation conditions, and other factors specific to the xylem, such as the specific gravity, modulus of elasticity, and presence of calcium and magnesium in the wood.

Effects of accelerated weathering test on the properties of larch wood

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7400-7415
Author(s):  
Liting Cheng ◽  
Yajing Di ◽  
Peng Zhao ◽  
Jian Dai ◽  
Zhiguo Yang ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Wood Properties ◽  
Sem Analysis ◽  
Accelerated Weathering ◽  
Electron Microscopic ◽  
Larch Wood ◽  
Light Yellow ◽  
Accelerated Weathering Test ◽  
Preset Time ◽  
The Relationship

To investigate the changes of larch wood properties under the influence of long-standing exposure to the environment, the QUV accelerated weathering tester (fluorescent UV and condensation testers) was used to accelerate the weathering of wood within a given preset time, and the changes were studied by analogue simulation. The wood color changed noticeably under different weathering time, and it gradually darkened from light yellow to deep reddish brown. Scanning electron microscopic (SEM) analysis revealed that as the weathering time increased, the cell wall was broken, the pits were cracked, and the tracheids were damaged. The results of the energy spectrum analysis (O/C (oxygen/carbon)) showed an increasing trend in the ratio, indicating that the wood underwent an oxidation reaction induced by light. From the values of the two testing indexes and their change patterns with weathering time, the same trend was observed, with the values of modulus of elasticity (MOE) in static bending being greater than that in dynamic bending Ed (the dynamic modulus of elasticity). However, the variability of MOE was greater than that of Ed. A comparative analysis of the two detection indicators was performed. The relationship between the proposed combined correction Ed and weathering time was: y = 0.0000001017 t2 – 0.0006 t + 9.77.

The Germans and their Jewish Neighbors on the Ukrainian Areas at the Second Half of the 19th Century

2020 ◽  
pp. 17-27
Author(s):  
D. Meshkov
Keyword(s):  
Everyday Life ◽  
19Th Century ◽  
Russian Empire ◽  
Early Years ◽  
Criminal Cases ◽  
South West ◽  
Multiethnic Population ◽  
The Russian Empire ◽  
The 19Th Century ◽  
The Relationship

The article presents some of the author’s research results that has got while elaboration of the theme “Everyday life in the mirror of conflicts: Germans and their neighbors on the Southern and South-West periphery of the Russian Empire 1861–1914”. The relationship between Germans and Jews is studied in the context of the growing confrontation in Southern cities that resulted in a wave of pogroms. Sources are information provided by the police and court archival funds. The German colonists Ludwig Koenig and Alexandra Kirchner (the resident of Odessa) were involved into Odessa pogrom (1871), in particular. While Koenig with other rioters was arrested by the police, Kirchner led a crowd of rioters to the shop of her Jewish neighbor, whom she had a conflict with. The second part of the article is devoted to the analyses of unty-Jewish violence causes and history in Ak-Kerman at the second half of the 19th and early years of 20th centuries. Akkerman was one of the southern Bessarabia cities, where multiethnic population, including the Jews, grew rapidly. It was one of the reasons of the pogroms in 1865 and 1905. The author uses criminal cases` papers to analyze the reasons of the Germans participation in the civilian squads that had been organized to protect the population and their property in Ackerman and Shabo in 1905.

scholarly journals Prediction of Maritime Pine Boards Modulus of Elasticity by Means of Sonic Testing on Green Timber

2021 ◽  
Vol 11 (4) ◽  
pp. 1748
Author(s):  
Giovanna Concu
Keyword(s):  
Modulus Of Elasticity ◽  
Structural Timber ◽  
Maritime Pine ◽  
Manufacturing Costs ◽  
Sonic Waves ◽  
Wet Condition ◽  
Structural Grade ◽  
The Relationship ◽  
Grade Yield

Timber buildings are experiencing a rapid diffusion due to their good performance and their sustainability; however, some steps of structural timber production process, such as drying, are energy-intensive and environmentally impactful, and many wood species are also affected by low yield. Therefore, it would be important to determine the quality of the green material, that is, in wet condition, before undergoing the most impactful and expensive production steps. This paper describes a research aimed at quantifying the variation of the dynamic modulus of elasticity MoEdyn, which is commonly used for structural timber mechanical grading, from wet to dry condition in Sardinian maritime pine boards to be used for the production of laminated timber, and to examine the relationship between wet and dry MoEdyn. The MoEdyn was determined from measurements of the velocity of sonic waves propagating through the boards. The results show that the dry MoEdyn can be estimated starting from boards sonic testing in the wet condition, so providing a basis for implementing Sardinian maritime pine pre-grading in order to obtain the reduction of manufacturing costs, the abatement of environmental impact, and the increase of structural grade yield.

Some Tree Growth – Wood Property Relationships of Eucalypts

1975 ◽  
Vol 5 (3) ◽  
pp. 424-432 ◽  
Author(s):  
J. E. Nicholson ◽  
W. E. Hillis ◽  
N. Ditchburne
Keyword(s):  
Wood Property ◽  
Basic Density ◽  
Wood Properties ◽  
Reaction Wood ◽  
Growth Strain ◽  
Fiber Structure ◽  
Tree Crown ◽  
Stem Form ◽  
The Relationship ◽  
Longitudinal Growth Strain

The relationship between level of longitudinal growth strain and stress, modulus of elasticity, basic density, volumetric shrinkage, fiber classification, and stem form was investigated with 10 Eucalyptusregnans regrowth trees. Close relationships were observed. It is suggested that variations in these properties within trees are closely controlled, possibly to enable optimum positioning of the tree crown in relation to its immediate environment. The concept of fiber structure varying as a response to environment is supported by the observed variation in wood properties within and between trees of this species. The often-reported association between eccentric radial growth and reaction wood was not substantiated in this study.The data indicate that if economically justifiable, it would be possible to segregate trees that are likely to contain material that is hard to season.

Nondestructive Evaluation of Red Oak and White Oak Species

2020 ◽  
Vol 70 (3) ◽  
pp. 370-377
Author(s):  
Cristian Grecca Turkot ◽  
Roy Daniel Seale ◽  
Edward D. Entsminger ◽  
Frederico José Nistal França ◽  
Rubin Shmulsky
Keyword(s):  
Modulus Of Elasticity ◽  
Longitudinal Vibration ◽  
Mechanical Tests ◽  
Modulus Of Rupture ◽  
Red Oak ◽  
Quercus Alba ◽  
White Oak ◽  
Static Modulus ◽  
Static Modulus Of Elasticity ◽  
The Relationship

Abstract The objective of this article is to evaluate the relationship between the dynamic modulus of elasticity (MOEd), which was obtained with acoustic-based nondestructive testing (NDT) methods, and static bending properties of two domestic hardwood oak species. The mechanical properties were conducted using static modulus of elasticity (MOE) and modulus of rupture (MOR) in radial and tangential directions. Mechanical tests were performed according to ASTM D143 on small clear, defect-free specimens from the two tree species: red oak (Quercus rubra) and white oak (Quercus alba). The MOEd was determined by two NDT methods and three longitudinal vibration methods based on the fast Fourier transform. The destructive strength values obtained in this study were within the expected range for these species. The MOE was best predicted by NDT methods for both species but also had a strong capability to predict MOR.

Aschersonia aleyrodis. [Descriptions of Fungi and Bacteria].

1984 ◽  
Author(s):  
B. L. Brady
Keyword(s):  
Costa Rica ◽  
Geographical Distribution ◽  
Solomon Islands ◽  
Western Hemisphere ◽  
Scale Insects ◽  
Infected Host ◽  
Santo Domingo ◽  
Eastern Hemisphere ◽  
Aschersonia Aleyrodis ◽  
The Relationship

Abstract A description is provided for Aschersonia aleyrodis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Scale insects (Coccidae) and whitefly (Aleyrodidae). GEOGRAPHICAL DISTRIBUTION: Costa Rica, Cuba, India, Jamaica, Santo Domingo, Solomon Islands, USA. According to Mains (1959) A. aleyrodis is very common in the Western hemisphere whereas A. placenta is common in the Eastern hemisphere. DISEASE: When the genus Aschersonia Montagne was described in 1848 the species were regarded as parasites of the leaves of the plants on which the insect hosts were located and it was only in 1894 that Webber recognized A. aleyrodis as entomogenous. Early work and the relationship with the ascomycete genus Hypocrella is extensively treated and illustrated in colour by Petch (1921). Sutton (1980) states that approximately 50 taxa have been described in the genus which is wholly entomogenous. Infection is mainly of young larvae, but mature larvae and pupae are also attacked. Larvae in the early stages of infection become swollen and by the time that hyphae emerge around the edge of the infected host the latter is already dead.

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