Jugo Ilic

Bio: Jugo Ilic is an academic researcher from Commonwealth Scientific and Industrial Research Organisation. The author has contributed to research in topics: Elastic modulus & Shrinkage. The author has an hindex of 9, co-authored 9 publications receiving 1893 citations.

IAWA list of microscopic features for softwood identification

Abstract: Pieter Baas – Leiden, The Netherlands Nadezhda Blokhina – Vladivostok, Russia Tomoyuki Fujii – Ibaraki, Japan Peter Gasson – Kew, UK Dietger Grosser – Munich, Germany Immo Heinz – Munich, Germany Jugo Ilic – South Clayton, Australia Jiang Xiaomei – Beijing, China Regis Miller – Madison, WI, USA Lee Ann Newsom – University Park, PA, USA Shuichi Noshiro – Ibaraki, Japan Hans Georg Richter – Hamburg, Germany Mitsuo Suzuki – Sendai, Japan Teresa Terrazas – Montecillo, Mexico Elisabeth Wheeler – Raleigh, NC, USA Alex Wiedenhoeft – Madison, WI, USA

Rapid prediction of wood stiffness from microfibril angle and density.

Abstract: Wood quality is rapidly becoming a major consideration in tree improvement programs. Rapid, cost-effective methods will be required to cope with the large numbers of samples (increment cores) generated by such programs. Wood stiffness, or longitudinal modulus of elasticity (EL) is one ofthe most important wood properties for solid timber applications and this paper describes a rapid method for predicting EL from measurements of density and microfibril angle (MFA). Very strong linear relationships have been found between E L , measured by a sonic resonance technique, and various combinations of wood density and MFA for 104 clearwood samples of Eucalyptus delegatensis R.T. Baker. Average MFA of each sample was measured in less than 1 minute by high-speed x-ray scanning diffractometry on SilviScan-2, a prototype automated wood microstructure analyzer. Density was measured gravimetrically. A small strip cut from one end of each sample was used for MFA analysis. In this study, density variation alone accounted for 70 percent of the variation in E L , while MFA alone accounted for 86 percent. Together, MFA and density accounted for 96 percent of the variation in E L . The results of this study indicate that density, MFA, and E L could be included in tree improvement programs using instruments based on SilviScan technology.

Relationship among the dynamic and static elastic properties of air-dry Eucalyptus delegatensis R. Baker

Abstract: ), wave velocity (VL) in the fibre direction, dynamic flexural elastic modulus (EF), logarithmic decrement (LD) in air-dry specimens of Eucalyptus delegatensis R. Baker, measuring 20 × 20 mm transversely and 300 mm long. The dynamic properties were compared with the static elastic modulus (MOE) and the modulus of rupture (MOR) obtained from three point bending tests. EL was very highly related to EF, MOE, MOR and air-dry density, whereas the relationship between VL and static moduli was highly significant, but less strong. VL was related positively to air-dry density, and negatively to static shear modulus (Longitudinal-Tangential and Longitudinal-Radial planes). EF was the single best predictor of both MOE and MOR. LD was negatively related to MOE and MOR. The association between the dynamic (GF) and static (GST) shear modulus values was only moderately good. The mean dynamic modulus was 3.4 times greater than the mean static value. EL may be used to estimate the true Young's modulus in specimens in which shear contributes significantly to bending.

Dynamic MOE of 55 species using small wood beams

Abstract: Nondestructive impact-induced resonance vibrations and spectral analysis were used to determine the dynamic modulus of elasticity (MOE) of specimens from 45 hardwood and 10 softwood species. Relationships were obtained between air-dry specimens measuring 20×20×300 mm and small wood beams measuring 20×2×150 mm (nominal) cut from them. Dynamic longitudinal elastic modulus (EL) and wave velocity (VL) in the fiber direction were determined from the larger specimens. These were compared with the dynamic flexural elastic modulus (ECB-cantilever mode) and the dynamic longitudinal elastic modulus (ELB) with the corresponding wave velocity (VBL) measured from the small beams. ECB and ELB were highly related to EL. VLB was similarly related to VL. The methods developed for small wood beams allow rapid evaluation of MOE from the outer wood of standing trees or they can be used for studies involving detailed localized evaluation of elastic wood properties.

Application of near infrared spectroscopy to a diverse range of species demonstrating wide density and stiffness variation

Abstract: The application of near infrared (NIR) spectroscopy to a large number of mixed species that display extremely wide variations in wood chemistry, anatomy and physical properties, is described. The mixed species samples were characterized in terms of density, longitudinal modulus of elasticity and microfibril angle. NIR spectra were obtained from the radial / longitudinal face of each sample and used to generate calibrations for the measured physical properties. The calibrations developed for density and longitudinal modulus of elasticity had the highest coefficients of determination (R2) and demonstrated that it is possible to develop general calibrations for these important wood properties across a wide range of species.The mixed species calibrations were used to estimate wood properties of two species, Eucalyptus delegatensis R.T. Baker and Pinus radiata D.Don. The results obtained for density and longitudinal modulus of elasticity indicated that mixed species calibrations can be used to rank trees. In practice the extreme variation of samples selected for this study would not be required. It is expected that refinement of calibrations, through sample selection, would provide more accurate prediction of physical properties.

Human occupation of northern Australia by 65,000 years ago

Abstract: The time of arrival of people in Australia is an unresolved question. It is relevant to debates about when modern humans first dispersed out of Africa and when their descendants incorporated genetic material from Neanderthals, Denisovans and possibly other hominins. Humans have also been implicated in the extinction of Australia’s megafauna. Here we report the results of new excavations conducted at Madjedbebe, a rock shelter in northern Australia. Artefacts in primary depositional context are concentrated in three dense bands, with the stratigraphic integrity of the deposit demonstrated by artefact refits and by optical dating and other analyses of the sediments. Human occupation began around 65,000 years ago, with a distinctive stone tool assemblage including grinding stones, ground ochres, reflective additives and ground-edge hatchet heads. This evidence sets a new minimum age for the arrival of humans in Australia, the dispersal of modern humans out of Africa, and the subsequent interactions of modern humans with Neanderthals and Denisovans. Optical dating of sediments containing stone artefacts newly excavated at Madjedbebe, Australia, indicate that human occupation began around 65,000 years ago, thereby setting a new minimum age for the arrival of people in Australia. When did humans first colonize Australia? The date of the initial landing on the continent that is now associated with cold lager and 'Waltzing Matilda' has been highly controversial. Dates from a site called Madjedbebe in northern Australia had put the presence of modern humans in Australia at between 60,000 and 50,000 years ago, but these results have since been hotly contested. Here, the results from a comprehensive program of dating of new excavations at the site confirm that people first arrived there around 65,000 years ago. The results show that humans reached Australia well before the extinction of the Australian megafauna and the disappearance of Homo floresiensis in neighbouring Indonesia.

Cellulose microfibril angle in the cell wall of wood fibres

Abstract: The term microfibril angle (MFA) in wood science refers to the angle between the direction of the helical windings of cellulose microfibrils in the secondary cell wall of fibres and tracheids and the long axis of cell. Technologically, it is usually applied to the orientation of cellulose microfibrils in the S2 layer that makes up the greatest proportion of the wall thickness, since it is this which most affects the physical properties of wood. This review describes the organisation of the cellulose component of the secondary wall of fibres and tracheids and the various methods that have been used for the measurement of MFA. It considers the variation of MFA within the tree and the biological reason for the large differences found between juvenile (or core) wood and mature (or outer) wood. The ability of the tree to vary MFA in response to environmental stress, particularly in reaction wood, is also described. Differences in MFA have a profound effect on the properties of wood, in particular its stiffness. The large MFA in juvenile wood confers low stiffness and gives the sapling the flexibility it needs to survive high winds without breaking. It also means, however, that timber containing a high proportion of juvenile wood is unsuitable for use as high-grade structural timber. This fact has taken on increasing importance in view of the trend in forestry towards short rotation cropping of fast grown species. These trees at harvest may contain 50% or more of timber with low stiffness and therefore, low economic value. Although they are presently grown mainly for pulp, pressure for increased timber production means that ways will be sought to improve the quality of their timber by reducing juvenile wood MFA. The mechanism by which the orientation of microfibril deposition is controlled is still a matter of debate. However, the application of molecular techniques is likely to enable modification of this process. The extent to which these techniques should be used to improve timber quality by reducing MFA in juvenile wood is, however, uncertain, since care must be taken to avoid compromising the safety of the tree.

A Review of Recent Near Infrared Research for Wood and Paper

Abstract: This review article introduces recent technical and scientific reports in terms of near infrared (NIR) spectroscopy in the wood and paper science and industry, where interest has increased during the last couple decades. Many researchers reported the NIR technique was useful to detect multi information in both chemical and physical properties of wood materials, although it was widely used in a state where characteristic cellular structure was retained. In the case of application of NIR spectroscopy to pulp and paper, many publications have pointed out its high probability as online measurement techniques during paper‐making process control. Arguments referred to the importance of NIR spectroscopy as fundamental and applied research of wood and paper.

Microfibril Angle: Measurement, Variation and Relationships – A Review

Abstract: Microfibril angle (MFA) is perhaps the easiest ultrastructural variable to measure for wood cell walls, and certainly the only such variable that has been measured on a large scale. Because cellulose is crystalline, the MFA of the S2 layer can be measured by X-ray diffraction. Automated X-ray scanning devices such as SilviScan have produced large datasets for a range of timber species using increment core samples. In conifers, microfibril angles are large in the juvenile wood and small in the mature wood. MFA is larger at the base of the tree for a given ring number from the pith, and decreases with height, increasing slightly at the top tree. In hardwoods, similar patterns occur, but with much less variation and much smaller microfibril angles in juvenile wood. MFA has significant heritability, but is also influenced by environmental factors as shown by its increased values in compression wood, decreased values in tension wood and, often, increased values following nutrient or water supplementation. Adjacent individual tracheids can show moderate differences in MFA that may be related to tracheid length, but not to lumen diameter or cell wall thickness. While there has been strong interest in the MFA of the S2 layer, which dominates the axial stiffness properties of tracheids and fibres, there has been little attention given to the microfibril angles of S1 and S3 layers, which may influence collapse resistance and other lateral properties. Such investigations have been limited by the much greater difficulty of measuring angles for these wall layers. MFA, in combination with basic density, shows a strong relationship to longitudinal modulus of elasticity, and to longitudinal shrinkage, which are the main reasons for interest in this cell wall property in conifers. In hardwoods, MFA is of more interest in relation to growth stress and shrinkage behaviour.

Character States, Morphological Variation, and Phylogenetic Analysis: A Review

Abstract: The step in cladistic analysis that has received least attention is delimitation of char- acter states, there usually being little justification for their delimitation. It is generally assumed that states of cladistic characters are discrete, even when variation is quantitative. I show here that a majority of the character states of obviously quantitative characters used in lower-level cladistic studies in botany over the last generation are ambiguous even when ingroup variation alone is analyzed. Consideration of variation in the outgroup may compromize either the states recognized in the ingroup and/or the polarity that they are subsequently assigned. Furthermore, many so- called qualitative characters are based on a quantitative phenomenological base filtered through the reified semantic discontinuities of botanical terminology; such characters face the problems of their more obviously quantitative relatives. Methods for delimiting states within quantitative char- acters are examined. Some produce gaps in the variation by redefining the character, scoring the intermediates in a distinctive fashion, performing phylogenetic analyses within the terminal taxa, or changing the hierarchical level at which the variation is evaluated. Others produce states by manipulation of the statistical properties of the variation of the ensemble of taxa being studied. These latter methods often allow greater resolution of the phylogeny, but at the cost of lowering the significance of the most parsimonious tree. The underlying assumptions of the two sets of methods are briefly analyzed. Problems manifest in the division of continuous variation into char- acter states suggest a reappraisal of the early steps of cladistic analysis; in practice, character states often seem to be delimited in conjunction with developing ideas of the phylogeny, rather than in a step prior to a phylogenetic analysis. It is recommended that character states be delimited by carefully analyzed discontinuities (not necessarily absolute gaps) in the variation, attention having been paid to variation in the outgroup, and that "morphological" characters in general are assumed to be quantitative unless demonstrated otherwise. Explicit justification for the delimitation of char- acter states should be given as a matter of course in all phylogenetic studies.