The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Torbjørn Helle - One of the best experts on this subject based on the ideXlab platform.
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Assessment of transverse dimensions of wood tracheids using SEM and image analysis
Holz als Roh- und Werkstoff, 2002Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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Assessment of Fibre transverse dimensions using SEM and image analysis
2002Co-Authors: Philip André Reme, Per Olav Johnsen, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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Quantitative assessment of mechanical Fibre dimensions during defibration and Fibre development
2001Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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On the difference in response to refining between Norway Spruce and Scots Pine
2001Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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The Fibre characteristics of shives initiating web rupture
Nordic Pulp & Paper Research Journal, 2000Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
Agnese Vigano - One of the best experts on this subject based on the ideXlab platform.
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comparative proteomic profile of rat sciatic nerve and gastrocnemius muscle tissues in ageing by 2 d dige
Proteomics, 2009Co-Authors: Daniele Capitanio, Michele Vasso, Chiara Fania, Manuela Moriggi, Agnese ViganoAbstract:Ageing induces a progressive morphological change and functional decline in muscles and in nerves. Light and electron microscopy, 2-D DIGE and MS, were applied to profile the qualitative and quantitative differences in the proteome and morphology of rat gastrocnemius muscle and sciatic nerve, in healthy 22-month-old rats. At muscle level, morphological changes are associated to Fibre atrophy accompanied by myofibrillar loss and degeneration, disappearance of sarcomeres and sarcoplasmic reticulum dilatation, internal migration of nuclei, longitudinal Fibre Splitting, increment of subsarcolemmal mitochondria aggregates and increment of lipofuscin granules. Sciatic nerve shows myelin abnormalities like enfoldings, invaginations, onion bulbs, breakdowns and side axonal atrophy. Proteomic analysis identified changes correlated to morphological abnormalities in metabolic, contractile and cytoskeletal proteins, deregulation of iron homeostasis, change of Ca(2+) balance and stress response proteins, accompanied by a deregulation of myelin membrane adhesion protein and proteins regulating the neuronal caliber. By comparing proteomic results from the two tissues, 16 protein isoforms showed the same up and down regulation trend suggesting that there are changes implying a general process which may act as a signal event of degeneration. Only beta enolase and tropomyosin 1alpha were differentially expressed in the tissues.
Philip André Reme - One of the best experts on this subject based on the ideXlab platform.
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Assessment of transverse dimensions of wood tracheids using SEM and image analysis
Holz als Roh- und Werkstoff, 2002Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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Assessment of Fibre transverse dimensions using SEM and image analysis
2002Co-Authors: Philip André Reme, Per Olav Johnsen, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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Quantitative assessment of mechanical Fibre dimensions during defibration and Fibre development
2001Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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On the difference in response to refining between Norway Spruce and Scots Pine
2001Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
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The Fibre characteristics of shives initiating web rupture
Nordic Pulp & Paper Research Journal, 2000Co-Authors: Philip André Reme, Torbjørn HelleAbstract:The thesis comprises three parts: Existing methods for characterisation of Fibre crosssections have been improved, and new methods have been developed. These methods have then been applied to study the effects of wood characteristics and the pulping process on mechanical pulp Fibres. Links have been established between Fibre structure and paper properties such as surface smoothness and light scattering coefficient.New methods, based on SEM-images and image analysis, are described for providing cross-sectional Fibre dimensions for large Fibre populations, for wood tracheids (app. 60 000 tracheids in a wood trunk) and for processed pulp Fibres (app. 1000 Fibres per sample). The methods are suited e.g. for evaluation of changes in the Fibre cross-sections from wood to the finished paper, or for mapping of Fibre parameters within and between growth rings in a wood trunk. The treatment of data is discussed, showing how one may examine the changes in different groups of Fibres (earlywood Fibres, latewood Fibres, split Fibres) throughout a process.It is known from the literature that groundwood-based paper is superior to TMP-based paper with respect to printability. Fibres from SGW and PGW-pulp were found to be much more split in the longitudinal direction than TMP-Fibres at comparable freeness. Intact groundwood Fibres had thicker walls than intact TMP-Fibres, but nevertheless super calendered hand sheets made from groundwood Fibres were less roughened by moistening than were TMP-based sheets. Both for groundwood pulps and for TMPpulps, it was shown that reduced Fibre wall thickness and increased Fibre Splitting was beneficial for improved surface smoothness and opacity.Latewood defibrate easier than earlywood during refining. In the case of grinding, there was no particular preference for earlywood or latewood to be defibrated. Reject refining of groundwood reject was, however, found to be very important for defibration of latewood-containing shives. Pulps made from a raw material with more compact Fibres (high wall area to lumen area ratio) were found to defibrate easier, and contain less shives. It was found that refining tends to reduce wall thickness most on thickwalled parts of the Fibre, thus causing a reduction of the wall thickness variation around the perimeter.Earlywood Fibres were found to be preferentially split during refining. Most Fibre Splitting occurs during the primary stage, while the Fibres are firmly attached to chips or Fibre bundles. Latewood Fibre wall thickness decreases considerably more than earlywood Fibre wall thickness during refining. It seems that choosing an appropriate raw material is more effective than using excessive energy on reducing the wall thickness of thickwalled Fibres. Earlywood Fibres became more flattened during refining compared to latewood Fibres, possibly due to repeated compressions and relaxations in the refiner.The energy consumption to a given freeness was found to be considerably larger for Scots Pine than for Norway Spruce. However, the Fibre transverse dimensions did not differ much between Norway Spruce and Scots Pine. Pine pulps were far less developed than spruce pulps at similar energy level. A possible explanation for the large energy consumption may be that redistribution of extractives at the Fibre surface could reduce friction in the refiner. This hypothesis should be further explored.The results in this study improve the knowledge of which Fibre parameters that matter for surface smoothness and opacity of wood-containing publication paper. Further, this study elucidates how important Fibre parameters such as wall thickness and Fibre Splitting are altered during a refining process. The results may be utilized to identify possible ways of modifying the TMP-process in order to produce paper with improved surface smoothness and opacity.
Y Ramamohan - One of the best experts on this subject based on the ideXlab platform.
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Variable histomorphology of muscle in congenital muscular dystrophy
Journal of the neurological sciences, 1997Co-Authors: Sarala Das, Narayanappa Gayathri, M. Gourie-devi, Anisya-vasanth, Y RamamohanAbstract:Abstract Congenital muscular dystrophy (CMD) is a relatively uncommon disease with a controversial nosological status. That collagen synthesis could be the primary abnormality has been suggested earlier ( Fidzianska et al., 1982 ). Amongst eighteen cases of CMD diagnosed during the past twelve years, muscle biopsy in three cases revealed prominence of myoFibre necrosis and phagocytosis, and serum CPK was markedly elevated suggesting a rapidly progressive form. In twelve cases, marked increase in endomysial collagen, pronounced fallout of myoFibres and significant Fibre diameter variation was seen. This was associated with myonecrosis and regenerative activity of mild degree resembling the classical form of CMD. In the remaining three cases, polyfocal, polyphasic necrosis was noticed. Fibre Splitting was more frequently observed, better delineated in the enzyme histochemical preparations, affecting both Fibre types, while endomysial fibrofatty tissue was only moderately increased. The histomorphology in the latter group resembled that of limb girdle dystrophy. Ultrastructural findings in all the eighteen cases correlated well with light microscopic observations. Immunohistochemical studies done on three of the eighteen cases showed normal localization of dystrophin protein. Such variable histomorphology, revealing a spectrum of myopathic features, suggests that the primary change in CMD is likely to be in the myoFibre rather than in collagen synthesis.
Daniele Capitanio - One of the best experts on this subject based on the ideXlab platform.
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comparative proteomic profile of rat sciatic nerve and gastrocnemius muscle tissues in ageing by 2 d dige
Proteomics, 2009Co-Authors: Daniele Capitanio, Michele Vasso, Chiara Fania, Manuela Moriggi, Agnese ViganoAbstract:Ageing induces a progressive morphological change and functional decline in muscles and in nerves. Light and electron microscopy, 2-D DIGE and MS, were applied to profile the qualitative and quantitative differences in the proteome and morphology of rat gastrocnemius muscle and sciatic nerve, in healthy 22-month-old rats. At muscle level, morphological changes are associated to Fibre atrophy accompanied by myofibrillar loss and degeneration, disappearance of sarcomeres and sarcoplasmic reticulum dilatation, internal migration of nuclei, longitudinal Fibre Splitting, increment of subsarcolemmal mitochondria aggregates and increment of lipofuscin granules. Sciatic nerve shows myelin abnormalities like enfoldings, invaginations, onion bulbs, breakdowns and side axonal atrophy. Proteomic analysis identified changes correlated to morphological abnormalities in metabolic, contractile and cytoskeletal proteins, deregulation of iron homeostasis, change of Ca(2+) balance and stress response proteins, accompanied by a deregulation of myelin membrane adhesion protein and proteins regulating the neuronal caliber. By comparing proteomic results from the two tissues, 16 protein isoforms showed the same up and down regulation trend suggesting that there are changes implying a general process which may act as a signal event of degeneration. Only beta enolase and tropomyosin 1alpha were differentially expressed in the tissues.