The Experts below are selected from a list of 3630 Experts worldwide ranked by ideXlab platform
R. Hägglund - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the strain field in the vicinity of a crack-tip in an in-plane isotropic Paper Material
International Journal of Solids and Structures, 2007Co-Authors: Per Isaksson, R. HägglundAbstract:Abstract Strains, computed by the finite element method, are evaluated and compared to an experimentally determined strain field. The analyzed low-density Paper has been designed to ensure bond–breakage as the dominating damage mechanism and the Paper Material is approximately in-plane isotropic. An optical non-contact displacement measuring system has been used in fracture tests to determine the strain field in the crack-tip region of a pre-fabricated crack. Additionally, acoustic emission monitored tensile tests have been conducted to determine onset and evolution of damage processes and thereby enabling calibration of required constitutive parameters. The results suggest that the investigated Paper Material can tolerate significantly higher strains than what is predicted by a classic elastic–plastic J2-flow theory. Immediately before onset of the final fracture (i.e., localization), the experimental measured normal strain in the near-tip region is around 60% higher than the computed strain when using exclusively an elastic–plastic theory for the corresponding load while the strain computed utilizing a non-local damage theory is of the same order of magnitude as the experimentally measured strain. Hence, it seems essential to include a non-local continuum theory to describe strains in the near-tip region quantitatively correct for Paper Materials. It is demonstrated that path independence of the well-known J-integral does not prevail for this class of Material models. Only for the special situation of a homogenous damage field in the crack-tip region may the stress and strain fields be described by the well-known HRR-solutions.
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Analysis of the strain field in the vicinity of a crack-tip in an in-plane isotropic Paper Material
International Journal of Solids and Structures, 2007Co-Authors: Per Isaksson, R. HägglundAbstract:Analysis of the strain field in the vicinity of a crack tip in an in-plane isotropic Paper Material
Per Isaksson - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the strain field in the vicinity of a crack-tip in an in-plane isotropic Paper Material
International Journal of Solids and Structures, 2007Co-Authors: Per Isaksson, R. HägglundAbstract:Abstract Strains, computed by the finite element method, are evaluated and compared to an experimentally determined strain field. The analyzed low-density Paper has been designed to ensure bond–breakage as the dominating damage mechanism and the Paper Material is approximately in-plane isotropic. An optical non-contact displacement measuring system has been used in fracture tests to determine the strain field in the crack-tip region of a pre-fabricated crack. Additionally, acoustic emission monitored tensile tests have been conducted to determine onset and evolution of damage processes and thereby enabling calibration of required constitutive parameters. The results suggest that the investigated Paper Material can tolerate significantly higher strains than what is predicted by a classic elastic–plastic J2-flow theory. Immediately before onset of the final fracture (i.e., localization), the experimental measured normal strain in the near-tip region is around 60% higher than the computed strain when using exclusively an elastic–plastic theory for the corresponding load while the strain computed utilizing a non-local damage theory is of the same order of magnitude as the experimentally measured strain. Hence, it seems essential to include a non-local continuum theory to describe strains in the near-tip region quantitatively correct for Paper Materials. It is demonstrated that path independence of the well-known J-integral does not prevail for this class of Material models. Only for the special situation of a homogenous damage field in the crack-tip region may the stress and strain fields be described by the well-known HRR-solutions.
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Analysis of the strain field in the vicinity of a crack-tip in an in-plane isotropic Paper Material
International Journal of Solids and Structures, 2007Co-Authors: Per Isaksson, R. HägglundAbstract:Analysis of the strain field in the vicinity of a crack tip in an in-plane isotropic Paper Material
J.p.h. Van Wyk - One of the best experts on this subject based on the ideXlab platform.
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Isolation of cellulase enzyme from brown garden snail (Cornu aspersum) for the saccharification of waste Paper Materials.
MethodsX, 2019Co-Authors: T.m. Ndlovu, J.p.h. Van WykAbstract:Abstract Garden snails (Cornu aspersum) have been sacrificed by drowning the snails overnight in water. The visceral organs (inside the shell organs) have been separated from the foot as well as the shell and homogenized using tris−HCl buffer, pH 5. The homogenate of visceral organs was dialysed in distilled water at 4 °C for 18 h where after the dialysed Material was used to bio-convert the cellulose component of various waste Paper Materials into fermentable sugars such as glucose. Saccharification of the waste cellulose Materials was performed with the extracted snail cellulase during ten consecutive incubation periods of 2 h each. The amount of sugars produced during cellulase action on waste cellulose was determined by the dinitrosalicylic acid (DNS) method. All incubations were performed in triplicate and the percent saccharification of each Paper Material was determined as a fraction of the Paper Material exposed to cellulase action. • Cellulase extracted from brown garden snail • Saccharification of waste Paper using garden snail cellulase
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Relative saccharification and initial degradation rates of different waste Paper Materials by cellulase from Trichoderma viride
Journal of Applied Biosciences, 2016Co-Authors: K.m.p. Mokatse, H.s. Mhlanga, J.p.h. Van WykAbstract:Objectives : Solid waste accumulation, renewable and sustainable energy development are topical issues concerning many populations around the globe. Used Paper is defined as part of organic solid waste, which besides recycling is eventually dumped, incinerated or landfilled. A structural analysis revealed that cellulose, a major component of waste Paper, is a biopolymer composed of glucose units and when treated with cellulase enzymes, cellulose can be degraded into glucose a fermentable sugar. The aim of this investigation was to determine the relative saccharification of various waste Paper Materials when treated with cellulase from Trichoderma viride as well as the initial rate at which each Material was degraded. It was also at aim to determine the amount of sugar produced when each Paper Material was maximally degraded and the time taken for maximum cellulase catalysed hydrolyses. Methodology and Results : Various waste Paper Materials such as office Paper, foolscap Paper, filter Paper, Woolworths Paper (a local retailer) and cardboard were saccharified with T. viride cellulase during different incubation periods producing different amounts of sugar concentrations. The different initial saccharification rates of the Paper Materials were calculated by determining the amount of sugar produced during the initial period of incubation and it was concluded that different maximum sugar concentrations were obtained during saccharification of these used Paper Materials. Filter Paper took the longest time of 100 minutes to obtain maximum saccharification. The shortest period of 40 minutes to reach maximum saccharification was obtained during the degradation of newsPaper. The fastest rate of degradation was obtained from newsPaper at 0.028 mg.min -1 and the lowest rate was calculated for filter Paper at 0.0045 mg.min -1 . Cardboard produced the highest concentration of sugar at 8.0 mg.ml -1 while filter Paper produced the lowest at 1.4 mg.ml -1 . Conclusions and applications of findings : Different waste Paper Materials exhibit different susceptibilities for degradation by T.viride cellulase into glucose a fermentable sugar and as a result, different maximum amounts of sugars were obtained during bioconversion of the Papers. The time needed for maximum degradation differs for the different Paper products, which indicates that each Paper Material should be exposed to an unique bioconversion procedure ensuring a maximum sugar yield. Waste Paper exhibits the ability to be bioconverted into fermentable sugars thus could be applied as a renewable resource for bioproduct development. Keywords : Cellulase, Trichoderma viride , Waste Paper, Saccharification, Bioenergy
Jean-francis Bloch - One of the best experts on this subject based on the ideXlab platform.
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Estimation of microstructural properties from synchrotron X-ray microtomography and determination of the REV in Paper Materials
Acta Materialia, 2007Co-Authors: S. Rolland Du Roscoat, M. Decain, X. Thibault, Christian Geindreau, Jean-francis BlochAbstract:The porosity and specific surface areas of four industrial Paper Materials were determined from synchrotron X-ray microtomography. The porosity profile within the thickness of each Paper Material shows that a Paper sheet consists of three layers: two boundary layers, which present a strong gradient of porosity, and a “bulk” layer in which the porosity is almost constant. The anisotropy and the heterogeneity scale of the microstructure in the “bulk” layer was then analyzed by means of covariograms. It is shown that the microstructure of the four studied Papers is transverse isotropic and that the anisotropy of Papers containing fillers is less pronounced. Finally, the representative elementary volume (REV) for both studied microstructural properties was evaluated using two techniques: a systematic analysis of the influence of the volume size on the property measurement, and a statistical methodology. The REVs given by both methodologies are then compared.
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Estimation of microstructural properties from synchrotron X-ray microtomography and determination of the REV size in Paper Materials
Acta Materialia, 2007Co-Authors: Sabine Rolland Du Roscoat, M. Decain, X. Thibault, Christian Geindreau, Jean-francis BlochAbstract:The porosity and specific surface areas of four industrial Paper Materials were determined from synchrotron X-ray microtomography. The porosity profile within the thickness of each Paper Material shows that a Paper sheet consists of three layers: two boundary layers, which present a strong gradient of porosity, and a “bulk” layer in which the porosity is almost constant. The anisotropy and the heterogeneity scale of the microstructure in the “bulk” layer was then analyzed by means of covariograms. It is shown that the microstructure of the four studied Papers is transverse isotropic and that the anisotropy of Papers containing fillers is less pronounced. Finally, the representative elementary volume (REV) for both studied microstructural properties was evaluated using two techniques: a systematic analysis of the influence of the volume size on the property measurement, and a statistical methodology. The REVs given by both methodologies are then compared.
David J. Albert - One of the best experts on this subject based on the ideXlab platform.
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Field observations of four Aurelia labiata jellyfish behaviours: swimming down in response to low salinity pre-empted swimming up in response to touch, but animal and plant Materials were captured equally
Hydrobiologia, 2014Co-Authors: David J. AlbertAbstract:Jellyfish live in complex environments and must continually make behavioural choices. In field observations, adult Aurelia labiata were confronted with a conflict between swimming up elicited by touch of the manubrium and swimming down elicited by low salinity. Following a touch, downward-swimming medusae (1.5–2.0 m deep) turned and swam to within 0.5 m of the surface when the salinity in the top 1.5 m of the water column was greater than 20 ppt but medusae uniformly refused to swim up into the top 1.25 m when the salinity was less than 20 ppt even after being touched three times. The central nervous system of A. labiata appears to have neural circuitry that specifies their response when medusae encounter stimuli that elicit incompatible behaviours. Upward-swimming adult medusae had animal, vegetable or cellulose (Paper) Material dispersed ahead of them. Medusae captured each Material on the bell margin and transported it to a gastric pouch. Medusae displayed only minor behavioural differences in the process. Having sensory, neural and muscular systems organized to capture and pass to the stomach, a huge variety of Materials allows medusae to survive in different seasons and environments.
