Variation In Specific Gravity Research Articles

Determination of ring-level dynamic modulus of elasticity in loblolly pine from measurements of ultrasonic velocity and specific gravity

Abstract Wood stiffness (modulus of elasticity, MOE) is an important property for conifer wood, with the variability in MOE largely being a function of both the specific gravity (SG) (wood density) and the angle of the microfibrils within the S2 layer of longitudinal tracheids. Rapid analysis techniques can be used together to quantify MOE; while SG can be determined with relative ease, this is not the case for microfibril angle, requiring expensive X-ray diffraction equipment. An alternative to microfibril angle is to measure longitudinal acoustic velocity. The objective of this study was to measure and then model the within tree variation in dynamic MOE (MOEdyn) by developing the methodology to measure ultrasonic velocity (USV) in radial samples from pith to bark using ultrasonic frequencies (>20 kHz). A total of 419 pith-to-bark radial strips, collected from multiple height levels in 92 loblolly pine (Pinus taeda) trees, were processed to obtain matching SG (2mm longitudinal) and USV (8.2-mm longitudinal) samples. Ring-by-ring SG was measured using X-ray densitometry and time-of-flight USV was measured at a 10-mm radial resolution from pith to bark. A subset of samples was sent to SilviScan to determine microfibril angle using X-ray diffraction. The relationship between microfibril angle and USV was strong (R2 = 0.91, RMSE = 2.6°). Nonlinear mixed-effects models were then developed to predict radial variation in SG, USV and MOEdyn. Fixed effects for the models, which included cambial age and height of disk within tree, had pseudo R2 values of 0.67 for SG (RMSE = 0.051), 0.71 for USV (RMSE = 316 m/s) and 0.69 for MOEdyn (RMSE = 1.9 GPa). When combined with SG measurements from X-ray densitometry, USV measurements from pith to bark are a powerful tool for assessing variability in wood stiffness.

Space-time analysis of the longitudinal variation in wood specific gravity of teak and its effect on tree growth and development

The space-time structure of a teak wood specific gravity (SG) dataset was analyzed using a mixed-effects model. Spatial correlation increased in space, a phenomenon attributable to the maturation of apical meristems, while the temporal correlation of vascular meristems decreased over time. The decay of temporal correlation over time was attributed to the diminishing crown effect on the later formed wood further away from the pith, morphogen gradient, and probably changing microenvironmental conditions. The Kronecker product was used to collect spatiotemporal data on the intricate dynamic process of the evolution of the apical and lateral meristems. The results showed that height and relative radial distance (RRD) (i.e., the flow of time with wood formation) were statistically significant factors, with their interaction showing no significance. The results confirm the usefulness of using the space-time approach to elucidate the interaction between the apical and lateral meristems, two major inherent biological systems that control tree growth and wood formation dynamics. To understand the origins of patterns that vary both temporally and spatially in the tree, future work should describe the variation of SG within the tree due to increasing height (space) and diameter (age) as a matrix; then the correlation function can be modelled.

Correlations of HTSD to TBP and Bulk Properties to Saturate Content of a Wide Variety of Crude Oils

Forty-eight crude oils with variations in specific gravity (0.782 ≤ SG ≤ 1.002), sulphur content (0.03 ≤ S ≤ 5.6 wt.%), saturate content (23.5 ≤ Sat. ≤ 92.9 wt.%), asphaltene content (0.1 ≤ As ≤ 22.2 wt.%), and vacuum residue content (1.4 ≤ VR ≤ 60.7 wt.%) were characterized with HTSD, TBP, and SARA analyses. A modified SARA analysis of petroleum that allows for the attainment of a mass balance ≥97 wt.% for light crude oils was proposed, a procedure for the simulation of petroleum TBP curves from HTSD data using nonlinear regression and Riazi’s distribution model was developed, and a new correlation to predict petroleum saturate content from specific gravity and pour point with an average absolute deviation of 2.5 wt.%, maximum absolute deviation of 6.6 wt.%, and bias of 0.01 wt.% was developed. Intercriteria analysis was employed to evaluate the presence of statistically meaningful relations between the different petroleum properties and to evaluate the extent of similarity between the studied petroleum crudes. It was found that the extent of similarity between the crude oils based on HTSD analysis data could be discerned from data on the Kw characterization factor of narrow crude oil fractions. The results from this study showed that contrary to the generally accepted concept of the constant Kw characterization factor, the Kw factors of narrow fractions differ from that of crude oil. Moreover, the distributions of Kw factors of the different crudes were different.

Geotechnical behavior of fly ash-coal ash and bentonite clay composite as a landfill barrier material with special emphasis on desiccation cracks

Compacted clay barriers have been used to retard leakage of contaminated fluids from landfillsites. These liners may shrink, crack, desiccate and lose their integrity if the liner material doesn't have permeability (10−9 m/s), unconfined compressive strength (UCS = 200 kPa) and no desiccation cracks at all as per the CPCB-2001 and USEPA 1989 guidelines. These three parameters form the basis of utilizing any material as a liner material however bentonite clay (BC) due to excessive desiccation cracks upon drying and wetting events can't be used individually. The usual practice to overcome failure, of barrier material the usual practice is to amend BC with sand though being costly and unsustainable. Recently, Fly ash (FA) and Coal ash (CA) byproducts from thermal power plant, have been explored as a substitute of sand in landfill liner material for sustainable practices. The purpose of this study is to investigate and and compare the various composition of B-FA and B-CA in terms of adequate strength, permeability, and shrinkage/desiccation in such a way to meet the CPCB-2001 and USEPA 1989 guidelines. The variation of specific gravity, liquid limit, plastic limit, and DFSI with varying compositions of bentonite was also studied. The present study demonstrates that with the increment of BC permeability was found to decrease and 80CA20B, 80FA20B, 80FA15B5CA combinations were meeting CPCB-2001 permeability criterion. To replicate the field condition the overburdening pressure was varied from 100 to 800 kPa and the permeability was found to be within the prescribed range for the three compositions. In total, 72 UCS, including triplicates for 7, 14 and 28 days, were conducted to see if any pozzolanic reaction was ensuingand its effect on the strength. The maximum UCS was found to be 302 kPa for 80CA20B composition while 277 kPa for 80FA20B. Strength Improvement Factor (SIF) and Mobilized peak strain factor (MPSF) were found to be maximum for the 80CA20B composition for 28 days as 1.54 and 0.44 respectively. The composition 80CA20B demonstrated better desiccation crack resistance behaviour than 80FA20B and 80FA15B5CA. The volumetric shrinkage for 80CA20B, 80FA20B and 80FA15B5CA were 4.6, 10.49 and 4.2%. Further, there were no desiccation cracks observed if the volumetric shrinkage is around 4%. The water retention behavior of all the three compositions was almost same. The microstructure analysis for morphology, compositional characterization, and thermal analysis of the various constituents was also carried out.

Radial patterns of specific gravity variation in North American conifers

An extensive summary of publications reporting radial specific gravity (SG) variation for North American conifers is presented. SG varies from pith to bark in three distinct patterns before reaching asymptomatic values: Type 1 (SG increases with cambial age), Type 2 (SG is initially high at the pith, then decreases with cambial age, before increasing), and Type 3 (SG decreases with cambial age). Pinaceae have either a Type 1 or 2 pattern (majority are Type 2). Cupressaceae have a Type 3 pattern, but radial SG data do not exist for some species. We reviewed publications in table 7-1 of Panshin and de Zeeuw (the 1970 edition) which reports SG variation by species and Type (the 1980 edition has an equivalent table but does not reference publications), examining sampling strategies and radial patterns. For a small number of species, Type was either incorrectly interpreted or sampling made a conclusion regarding pattern of radial variation impossible. Specific examples of mislabeled Types reported by Panshin and de Zeeuw for Douglas-fir ( Pseudotsuga menziesii), lodgepole pine ( Pinus contorta), red pine ( Pinus resinosa) and shortleaf pine ( Pinus echinata), and western redcedar ( Thuja plicata) are described. We conclude for nearly all species the pattern of radial SG variation is consistent; however, different patterns have been reported for eastern white pine ( Pinus strobus) and subspecies of Douglas-fir and ponderosa pine ( Pinus ponderosa).

Wood specific gravity in Indian forests: A review.

Wood specific gravity (WSG) is an important attribute for biomass estimation of forest trees. It is an important factor in converting forest volume into biomass. However, a number of factors like climatic condition, geographic location, management practice, age of tree, location of sample collection etc. may affect WSG. In India, forests have been classified into 6 major groups, 16 groups and other sub groups on the basis of climatic, edaphic and successional variations. A number of studies conducted on above ground biomass and carbon stock using non-destructive method used global, regional or reported WSG leading to inaccuracies in biomass estimation. The present paper is a comprehensive review on methodology of wood specific gravity estimation, wood specific gravity values of a number of species reported from different forest groups of India. A total of 88 critical research papers and reports for last 20 years were found meeting the aims, were collected from relevant sources. Methodology for determining WSG is discussed for accurate estimation. Comparative analysis of common species distributed in different forest groups does not show a generalized trend for WSG, as the same forest group does not exhibit similar WSG in tree species. However, it is evident that juvenility effect has greater bearing on wood specific gravity variation than climate. Analysis of data shows a greater bearing of edaphic factor on WSG, than the climatic factor. It is suggested that for estimation of biomass, habitat specific WSG is ideal to attain accuracy.

Modelling specific gravity and diameter inside bark of western hemlock and Sitka spruce growing in southeast Alaska

Western hemlock (Tsuga heterophylla (Raf.) Sarg.) and Sitka spruce (Picea sitchensis (Bong.)) are two commercially important species in Alaska, with harvests beginning to focus on naturally regenerated young-growth. We developed within-tree models of ring specific gravity (SG) and diameter inside bark (DIB) for young-growth western hemlock and Sitka spruce. Eight even-aged stands (age <75 years) in southeast Alaska were felled and disks collected from multiple height levels; 128 trees and 451 disks were collected for western hemlock, and 217 trees and 952 disks were collected for Sitka spruce. Radial strips were prepared and scanned using X-ray densitometry. We fitted nonlinear mixed-effects models to the data, with cambial age, height within tree, and dominance class used as explanatory variables. The R2 values (fixed effects only) for the SG models were 0.48 and 0.42 for western hemlock and Sitka spruce, respectively. The corresponding fit indices (R2) for the DIB models were 0.86 and 0.85 for western hemlock and Sitka spruce, respectively. Tree maps depicting the within-tree variation in SG showed more variability in Sitka spruce than in western hemlock. The wood and growth properties of young-growth trees in Alaska will continue to become more important as the US Forest Service transitions away from harvesting old-growth trees.

Variation in specific gravity and carbon proportion of agroforestry tree species of Himalaya

Country-specific emission factors for the Agriculture, Forestry, and Other Land Use (AFOLU) sector are important for the national greenhouse gas (GHG) inventory. Carbon stocks of trees outside forests (TOF) and agroforestry is lacking due to the unavailability of wood density and carbon fraction of various tree species. The present study is an attempt to provide estimates of wood specific gravity (WSG) and carbon content (CC) in agroforestry tree species being cultivated by farmers in Garhwal Himalaya, India for precise estimation of biomass carbon of TOF and agroforestry. A total of 160 quadrats were laid randomly in agroforestry farms to represent the area of Pauri Garhwal and Rudraprayag districts of Garhwal Himalaya. A minimum of ten matured individuals for all 33 important agroforestry species including fruit trees were randomly selected from the quadrats. Minimum ten wood samples for each species were collected at 1.37 m height from ground for each individual. The samples were wood cores to the pith and were extracted from trees circumference using an increment borer for estimation of WSG and CC. The WSG of Carica papaya was minimum to the tune of 0.16 g cm−3 and maximum for Quercus leucotrichophora with 0.81 g cm−3. The carbon content varied from 36.37% for Carica papaya to 46.52% for Pinus roxburghii. The results of the present study differed from the earlier reports for other locations suggesting the importance of developing data set on WSG and CC for precise estimation of biomass carbon stock. The estimates of WSG and CC of agroforestry tree species would complement and improve the accuracy of national GHG inventory reporting in India for tree cover. Moreover, the accurate evaluation of carbon stock would be the enabling factor for the formulation of suitable policies and programmes for forest conservation, and sustainable rural livelihood through land use based adaptation and mitigation option.

Variation in Urinary Stone Parameters Throughout the Day and the Effect of Increased Fluid and Citrate Supplementation.

Background: Because 24-hour urine collections are cumbersome, many studies have evaluated the use of spot urine samples as a substitute, mostly finding poor concordance between the two. Daily variation in stone parameters probably contributes to the lack of concordance, but specific variation in various stone parameters is not well delineated. The variations likely lead to peaks and troughs, which can increase the risk of stone formation. Methods: We prospectively recruited 20 nonstone-forming patients, recording their total fluid intake over 24 hours and collecting voids at first morning, 9 to 10 A.M., 1 to 2 P.M., and 4 to 5 P.M. for evaluation of pH, specific gravity, calcium, citrate, and creatinine. Participants were then asked to double their fluid intake and take a daily True Lemon supplement over the course of the next 3 days. Urine was recollected postintervention. Results: Baseline [citrate]/[creatinine] increased throughout the day such that the 5 P.M. level was significantly higher compared with first void (0.58 vs 0.42, p = 0.027); [calcium]/[creatinine] daily variation was not statistically significant, but showed a distinct pattern that was present in both sets of collections. Daily [calcium]/[citrate] variation was significantly (p = 0.004) and consistently highest in the early morning on both day 1 (0.43) and day 4 (0.45). There was no significant variation in specific gravity and pH. Increasing fluid intake and citrate supplementation increase the daily variation in pH and [citrate]/[creatinine], but did not increase the values compared with their respective preintervention void times. There was also no detectable postintervention effect on [Ca]/[creatinine] or specific gravity. Conclusions: Urinary citrate concentration follows a circadian pattern, while urinary calcium has a diurnal excretion pattern. [Calcium]:[citrate] is highest in the early morning, indicating a high-risk time of day for stone formation. Spot urine samples identify a key time of day, which 24-hour urine collections may miss, for clinical monitoring.

Processing Attributes and Chips Quality of Promising Potato Clones under Different Slice Treatments in Bhaktapur, Nepal

A study was conducted to evaluate processing attributes of different potato clones (genotype) and their effect in chips quality in combination with different potato slice treatments in Bhaktapur, Nepal from January to April 2018. Six potato clones (PRP 35861.18, CIP 384866.5, PRP226267.11, CIP 388676.1, PRP 858676.1 and Desiree) were allocated in Randomized Complete Block Design with four replications. Significant variation among the potato clones was found with respect to dry matter and reducing sugar content. PRP 858676.1 showed the highest dry matter whereas the lowest reducing sugar content was with CIP 384866.5. Variation in specific gravity and total soluble solidwas not found statistically significant. Chips were prepared in two factorial design with 3 replications, following the protocol of National Potato Research Program. First factor was potato clones and the second factor was slice treatments viz; cold water, 0.5% NaCl solution and warm water at 45ºC. This study revealed significant variation in chips colour, taste & flavour, crispiness, overall acceptability and recovery percent. Clone CIP 388676.1 with slices treated with cold water produced best quality chips while highest recovery percent was given by PRP 858676.1 treated with warm water at 45ºC. Superior quality of chips was obtained with CIP 388676.1 followed by Desiree, CIP 384866.5 and PRP 858676.1. Thus, potato clones CIP 388676.1, Desiree, CIP 384866.5 and PRP 858676.1 needs further evaluation for chips quality and slice treatment with cold water should be recommended for good quality chips production.

P1837THE HISTORY OF THE URINES SPECIFIC GRAVITY TEST FROM THE 15TH CENTURY UNITL TODAY

Abstract Background and Aims To present the history of the specific gravity test in the study of urines from the 15th cent. AD until today. Method The first description of a hydrometer, the progenitor of the urinometer, appears in the fifteenth letter from Synesius of Cyrene to the Greek scholar Hypatia of Alexandria, from the 5th century AD. However, its evolution to the urinometer took 15 centuries until 1849, when Johann Florian Heller (1813-1871) introduced it. During the next two centuries, we note a rapid improvement of the appropriate laboratory instruments and a wide acceptance of the importance of specific gravity for the evaluation of urine. We present passages from relevant texts from the discussed period. Results The first call for attention to measuring urine weight comes from Nicolas of Cusa’s work The Layman: Experiments with Weights, where we read “Accordingly, since the weight of blood or the weight of urine is different for a healthy man and for a sick man or for a youthful man and an elderly man or for a German and an African, wouldn’t it be especially useful to a physician to have all these differences recorded? Orator: Most certainly”. The theoretical proposal was solidified in Francis Bacon’s Novurn Organum (1620): “Neither the naked hand nor the understanding left to itself can effect much. It is by instruments and helps that the work is done”. Herman Boerhaave, in 1753, weighed the distilled urine residue in order to calculate its density, a complicated and time-consuming procedure. Later, Groenevelt J. in The Rudiments of Physick writes “The particles in it sink or float according to their own gravity [specific!], but their position is also dependent on the thickness of the urine [albumin in it plus formed particles].” Osborne, in 1820, made a genius comparison “When a mucous cloud is present [in the urine] it ascends and descends in the fluid according to specific gravity, thus serving the purpose of a hydrometer”. Becquerel, in 1842, laid out tables calculating the solid articles in urines of given specific gravity. Graves, in 1866, reported intermittent albuminuria with a parallel variation of the specific gravity of urine in infectious disease. The same year, an article in the London Medical Gazette: Or, Journal of Practical Medicine, and another one in The New York Lancet stress the variation of specific gravity in the course of a renal disease. Clover R.M. in the Case of sialorrhoea (1846) states that specific gravity may vary greatly even with the same amount of solids and fluid due to fluid heterogeneity. In 1848, Garrod describes a bottle for measuring urine specific gravity. Johann Florian Heller introduced the mercury-based floating urinometer in 1849 thus greatly facilitating the test of urine specific gravity. The increasing demand for the test’s application resulted in the discovery of refined laboratory instruments, such as the refractometer. Very recently, urine specific gravity is considered an accurate renal function marker, equal to creatinine clearance or proteinuria levels (Constantiner M. et al, Am J Kidney Dis., 2005 May;45(5):833-41. and Anestis SF et al, Am J Primatol., 2009 Feb;71(2):130-5). Conclusion It seems that the understanding of urine specific gravity underwent “mechanisation”, from its inception as the use of the sediment’s location in the vial to access it, during the Middle Ages to complex apparatuses like refractometers. Originating in the Classical and Middle Ages mainly from the East, it obtained its sound scientific background in the West from the Renaissance onwards. After debate on its usefulness, it is again a vital tool for assessing renal damage.

Wood Anatomical Features and Physical Properties of Fast Growing Red Meranti from Line Planting at Natural Forest of Central Kalimantan

High productivity fast growing species plantation establishment such as the line planting of red meranti (i.e Shorealeprosula and Shorea parvifolia) with intensive silviculture is one potential solution to improve wood supply for industries in Indonesia. However, the information of anatomical properties and wood properties of these two species related to the influence of the line planting system and tree growth rate is limited. This paper studies the anatomical features, wood cell proportions, fiber dimensions and physical properties of wood in radial variation in relation to the line planting effect and tree growth rate. Wood of the trees grown in the line planting system showed higher proportion of vessel element compared to those of wood from natural forest. The vessel diameter of wood from the line planting was also larger than that of in wood from natural forest. The specific gravity of wood from Shorea parvifolia grown on the line planting was higher than that of wood grown in natural forest. The variation of specific gravity on wood portion near to the pith of Shorea leprosula and Shorea parvifolia trees grown on the line planting was related to the variation of the cell wall thickness. The bigger diameter of trees grown or the faster growth rate in the line of planting at the same age shows the greater vessel diameter in wood of Shorea leprosula and Shorea parvifolia and greater specific gravity of Shorea parvifolia wood.

Effect of Processing Methods and Storage Time on Physical Characteristics of Palm Oil

The effect of processing methods and the storage time on the physical characteristics of palm oil was determined. Samples of palm oil were produced using four processing methods (Hot Extraction; Cold Extraction; Hot Extraction with Red Sand and Mechanized Extraction), packaged in plastic containers and stored at ambient temperature for 0 to 3 month(s). There was significant increase in the following physical characteristics of the palm oil samples due to the storage time: cloud point (21.13 to 24.13oC), melting point (39.54 to 41.88oC) and moisture content (0.068 to 0.390%). However, significant decrease occurred in the following characteristics: smoke point (195.30 to 186.3oC), flash point (252.37 to 244.62oC), fire point (314.87 to 306.37oC) and refractive index (1.45 to 1.37). The effects of the four processing methods on the physical characteristics of palm oil were determined. Processing methods had no significant variations in specific gravity (0.902 to 0.905) and fire point (309.62 to 313.25oC) while significant variations occurred in cloud point (22.38 to 23.56oC), smoke point (188.38 to 195.50oC), melting point (40.16 to 41.63oC), flash point (240.75 to 268.50oC), moisture content (0.08 to 0.37%) and refractive index (1.39 to 1.44). Mechanized extraction method of palm oil was observed as the best method because its palm oil had the least specific gravity (0.902±0.006), least cloud point (22.38 ±1.75oC), highest smoke point (195.50±1.41oC), least melting point (40.16±1.03oC), highest flash point (218.50±3.67oC), highest fire point (313.25±2.96oC), least moisture content (0.08±0.02%) and highest refractive index (1.44±0.01). Similar study on the effect of processing methods and storage time on chemical properties of palm oil is recommendable.

Hydration Effects on Specific Gravity and Void Ratio of Cemented Paste Backfill

This article presents the results of a laboratory study on the variation of specific gravity (Gs) and void ratio (e) in a cemented paste backfill (CPB) with different cement contents and curing times. CPBs consist of a mixture of mine tailings, portland cement, and mine process water. In this study, a helium stereopycnometer device was used to determine Gs for specimens having cement contents of 3.0, 5.3, 7.5, and 11.1 % by the weight of dry tailings. Curing times of 4 h, 1, 3, 7, 14, and 28 days were considered for testing purposes. In total, 240 helium stereopycnometer tests were conducted in this study, which shows that Gs decreases in the CPB specimens as specimens cure over time and the cement hydrates. Furthermore, 96 tests were conducted to determine e of the CPB specimens with different combinations of cement contents and curing times. The results of these tests indicate that similar to Gs, e decreases with an increase in curing time as the specimens hydrate. The reduction in Gs and e is attributed to the formation of hydration products, which have a lower density than the cement and fill the void space between the particles. The results show that the variation of Gs that is due to the hydration process should be considered in the calculation of e; otherwise, this physical property, especially for specimens with high cement contents, is overestimated.

Effect of processing methods and storage time on physical characteristics of palm oil

The effect of processing methods and the storage time on the physical characteristics of palm oil was determined. Samples of palm oil were produced using four processing methods (Hot Extraction; Cold Extraction; Hot Extraction with Red Sand and Mechanized Extraction), packaged in plastic containers and stored at ambient temperature for 0 to 3 month(s). There was significant increase in the following physical characteristics of the palm oil samples due to the storage time: cloud point (21.13 to 24.13oC), melting point (39.54 to 41.88oC) and moisture content (0.068 to 0.390%). However, significant decrease occurred in the following characteristics: smoke point (195.30 to 186.3oC), flash point (252.37 to 244.62oC), fire point (314.87 to 306.37oC) and refractive index (1.45 to 1.37). The effects of the four processing methods on the physical characteristics of palm oil were determined. Processing methods had no significant variations in specific gravity (0.902 to 0.905) and fire point (309.62 to 313.25oC) while significant variations occurred in cloud point (22.38 to 23.56oC), smoke point (188.38 to 195.50oC), melting point (40.16 to 41.63oC), flash point (240.75 to 268.50oC), moisture content (0.08 to 0.37%) and refractive index (1.39 to 1.44). Mechanized extraction method of palm oil was observed as the best method because its palm oil had the least specific gravity (0.902±0.006), least cloud point (22.38 ±1.75oC), highest smoke point (195.50±1.41oC), least melting point (40.16±1.03oC), highest flash point (218.50±3.67oC), highest fire point (313.25±2.96oC), least moisture content (0.08±0.02%) and highest refractive index (1.44±0.01). Similar study on the effect of processing methods and storage time on chemical properties of palm oil is recommendable.

Mechanical Properties of Cocos nucifera Wood Planted Around Mt. Merapi, Yogyakarta

This study presented test results of mechanical properties of Cocos nucifera wood that were planted around Mt. Merapi, Yogyakarta. The test specimens were obtained from trees that had been exposed to pyroclastic flow during the 2010 volcanic eruption as indicated by dark colour of the outer bark. Test set-up was designed according to ASTM D143-94 and the mechanical properties, which are determined based on the lower 5% exclusion limit, were bending strength, shear strength, dowel bearing strength and compressive strength. Results of the specific gravity measurement showed significant variation of specific gravity between the inner part (close to the pith) and the outer part (far from the pith) in a cross-section. Since mechanical properties generally depend upon specific gravity, it was decided to divide the wood specimens into two groups: specimens from the inner part and specimens from the outer part. Most of the mechanical properties of wood specimens from the inner part, except for bending strength, were found to be much lower than E10 grade of the Indonesian National Standard (SNI). Hence it is not recommended for any structural use. In the case of wood specimens from the outer part, their mechanical properties were as follows: bending strength 83.66 MPa; shear strength parallel to grain 4.41 MPa; dowel bearing strength parallel to grain 40.65 MPa; dowel bearing strength perpendicular to grain 25.88 MPa, compressive strength parallel to grain 37.89 MPa; and compressive strength perpendicular to grain 7.48 MPa. It seemed that the wood specimens from the outer part had excellent mechanical properties especially in bending, but their shear strength is extremely low.

Some Properties of Astronium graveolens Wood Along the Stem

ABSTRACT We investigated the axial variation of specific gravity, shear parallel to the grain and anatomical features of Astronium graveolens wood and related these properties to the anatomy along the stem. We felled five 20-year-old trees and cut discs from four different stem heights, including stem base, 1 meter, 2 meters and 3 meters, for a total of 20 discs, and studied wood samples near the bark and at the base of trunk. Axial variations found appear to provide a balance between mechanical strength of the wood at stem base by the higher density and higher shear by the increase in ray frequency that contributes to locking the vertical cells and growth rings, thus preventing the stem from easily breaking when bent. For hydraulic conductivity, vessels with smaller diameter and frequency at the stem base help prevent the occurrence of embolisms that would reduce water flow along the main stem.

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood.

ContextWood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing). However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass.MethodsRadial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood).ResultsWood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity variance was explained by species only (45%) followed by a redundant part between species and regeneration guilds (36%). Despite substantial variation in wood specific gravity profiles among species and regeneration guilds, we found that values from the outer wood were strongly correlated to values from the whole profile, without any significant bias. In addition, we found that wood specific gravity from the DRYAD global repository may strongly differ depending on the species (up to 40% for Dialium pachyphyllum).Main ConclusionTherefore, when estimating forest biomass in specific sites, we recommend the systematic collection of outer wood samples on dominant species. This should prevent the main errors in biomass estimations resulting from wood specific gravity and allow for the collection of new information to explore the intraspecific variation of mechanical properties of trees.

Intra clonal variations of specific gravity and selected mechanical properties of Eucalyptus tereticornis Sm.

Intra clonal variation of specific gravity (sp. gr.) and selected mechanical properties in 4–5 years old trees of five clones of Eucalyptus tereticornis Sm. developed by ITC Bhadrachalam (clone 3, 4, 6, 7 and 10) is reported. Four trees of each clone were studied from Sarapakka, Andhra Pradesh (India). There is a significant difference within the clone in the sp. gr. for all the clones except for clone 10. Differences in within clone bending properties (MOE, MOR and FS at LP) in green and air-dry condition on the contrary are non-significant in all the clones. Very similar trend is observed for CS at LP (except for clone 7) and hardness (except for end hardness in clone 4 for dry condition and clone 7 for side hardness in green condition). Maximum crushing strength (MCS), however, showed significant difference in all the clones except for clone 7. In general, it can be concluded that difference in strength properties is non-significant and do not follow the trend of specific gravity. Trees of clone 4 have highest values for all the properties tested among the five clones. Trees of clones 3 and 10 have identical sp. gr. and are lowest among all the clones. MCS and CS at LP is lowest in trees of clone 10 closely followed by clone 3. Trees of clone 3 have lowest bending properties and hardness properties closely followed by clone 10. On an average clone 10 reports the highest girth for all the trees followed by clone 6. Clone 4 reports the lowest girth for the trees. No specific trend was observed between sp. gr. verses strength properties and girth of the trees versus sp. gr. and strength properties although there seems to be general reduction in strength and sp. gr. with increase in girth.

Wood specific gravity variation among five important hardwood species of Kashmir Himalaya.

Wood Specific Gravity (SG) is a measure of the amount of structural material a tree species allocates to support and strength. In the present study, specific gravity varied among the five different woods at three different sites from 0.40 in Populus nigra at site III (Shopian) to 0.80 in Parrotiopsis jacquemontiana at site II (Surasyar). Among the three different sites, specific gravity varied from 0.73 to 0.80 in Parroptiosis jacquemontiana; in Robinia pseudoacacia it varied from 0.71 to 0.79; in Salix alba, it varied from 0.42 to 0.48; In Populus nigra it varied from 0.40 to 0.48 and in Juglans regia it varied from 0.59 to 0.66. On the basis of the specific gravity variation patterns these woods were categorized as light (Salix alba, Populus nigra) moderately heavy (Juglans regia) and moderately heavy to heavy (Robinia pseudoacacia, Parrotiopsis jacquemontiana) which predicts their properties like strength, dimensional stability with moisture content change, ability to retain paint, fiber yield per unit volume, suitability for making particleboard and related wood composite materials and suitability as a raw material for making paper.