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  • 101.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Shataeva, Larisa K.
    bInstitute of Macromolecular Compounds, Russian Academy of Science.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Separation of nucleoprotein complexes with antioxidant activity from yeast Saccharomyces cerevisiae2007Inngår i: Separation and Purification Technology, ISSN 1383-5866, E-ISSN 1873-3794, Vol. 53, nr 1, s. 64-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, complexes of nucleic acids and acidic nuclear proteins were isolated from baker's yeast cells of Saccharomyces cerevisiae by mild alkaline extraction followed by precipitation with acetic acid. The optimal composition of the buffer applied for extraction of nucleoprotein complexes was determined. The high and low molar mass fractions of the nucleoprotein complexes were separated using cross-flow microfiltration through track-etched membranes. The molar masses were determined by intrinsic viscosity measurements and the molar mass distribution in nucleoprotein complexes was studied by gel permeation chromatography. The protein component of the nucleoprotein complexes was purified on a strongly basic anion exchange resin. The high molar mass nucleoprotein complexes could induce the growth of culture cells of S. cerevisiae exposed to ultraviolet irradiation or treated with hydrogen peroxide

  • 102.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Shataeva, Larisa K.
    Institute of Macromolecular Compounds, Russian Academy of Science.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Yeast nucleopeptide complexes and their biological effect2004Inngår i: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 10, s. 162-Artikkel i tidsskrift (Fagfellevurdert)
  • 103.
    Butylina, Svetlana
    et al.
    Department of Chemical Technology, Lappeenranta University of Technology.
    Shataeva, Larisa K.
    Institute of Macromolecular Compounds, Russian Academy of Science.
    Nyström, Marianne
    Department of Chemical Technology, Lappeenranta University of Technology.
    Yeast nucleopeptide complexes and their biological effects2005Inngår i: Peptides 2004: Proceedings: Bridges Between Disciplines, Kenes Int. , 2005, s. 423-424Konferansepaper (Fagfellevurdert)
  • 104.
    Butylina, Svetlana
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Turku, Irina
    Fiber Composite Laboratory, School of Energy Systems, Lappeenranta University of Technology, Lappeenranta, Finland.
    Biodegradation and Flame Retardancy of Polypropylene-Based Composites and Nanocomposites2018Inngår i: Polypropylene-Based Biocomposites and Bionanocomposites / [ed] P. M. Visakh, Matheus Poletto, NJ, USA.: John Wiley & Sons, 2018, s. 145-175Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This chapter summarizes information about the biodegradation and flame retar- dancy of PP-based biocomposites and nano composites obtained from highly ranked journals published during the last two decades. The first part of this chapter deals with the biodegradation of PP-based composites. The second part of this chapter begins with a short description of the specific flammability of PP, followed by an overview of fire retardants and flame testing methods and standards. PP composites reinforced with commonly applied cellulosic fillers, such as wood, flax and others, as well as rarely used wool fibers are considered. The effect of different nanometric fillers alone or in combination with conventional fire retardants on the flammability of composites is also described. Along with comparative analysis of different fire retardants regarding their ability to decrease the flammability of PP matrix composites, the mechanism action and their possible synergy effects are highlighted.

  • 105.
    Carlsson, Daniel O.
    et al.
    Nanotechnology and Functional Materials, Department of Engineering Sciences, Box 534, Uppsala University, Uppsala University, Department of Engineering Science.
    Lindh, Jonas
    Nanotechnology and Functional Materials, Department of Engineering Sciences, Box 534, Uppsala University.
    Nyholm, Leif
    Uppsala University, Department of Chemistry, Angstrom Lab.
    Mattsson, Maria Stromme
    Uppsala University, Department of Engineering Science.
    Mihranyan, Albert
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Cooxidant-free TEMPO-mediated oxidation of highly crystalline nanocellulose in water2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 94, s. 52289-52298Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Selective oxidation of C6 hydroxyls to carboxyls through 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, where the oxidizing species (TEMPO+) is generated by cooxidants, such as NaBrO, NaClO or NaClO2, has become a popular way to modify the surfaces of nanocellulose fibrils in aqueous solutions. Employing highly crystalline nanocellulose from Cladophora sp. algae we demonstrate that the same degree of oxidation (D.O.) can be achieved within approximately the same time by replacing the cooxidants with electrogeneration of TEMPO+ in a bulk electrolysis setup. The D.O. is controlled by the oxidation time and the maximum D.O. achieved (D.O. 9.8%, 0.60 mmol g-1 of carboxylic acids and 0 mmol g-1 aldehydes) corresponds to complete oxidation of the surface-confined C6. This shows that TEMPO+ is not sterically hindered from completely oxidizing the fibril surface of Cladophora nanocellulose, in contrast to earlier hypotheses that were based on results with wood-derived nanocellulose. The oxidation does not significantly affect the morphology, the specific surface area (>115 m2 g-1) or the pore characteristics of the water-insoluble fibrous particles that were obtained after drying, but depolymerization corresponding to ∼20% was observed. For extensive oxidation times, the product recovery of water-insoluble fibrils decreased significantly while significant amounts of charge passed through the system. This could indicate that the oxidation proceeds beyond the fibril surface, in contrast to the current view that TEMPO-mediated oxidation is confined only to the surface.

  • 106.
    Carlsson, Daniel O.
    et al.
    Uppsala University, Department of Engineering Science.
    Mihranyan, Albert
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Stromme, Maria
    Uppsala University, Department of Engineering Science.
    Nyholm, Leif
    Uppsala University, Department of Chemistry, Angstrom Lab.
    Tailoring porosities and electrochemical properties of composites composed of microfibrillated cellulose and polypyrrole2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 17, s. 8489-8497Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Composites of polypyrrole and nanocellulose (PPy/nanocellulose) have a high potential as electrodes in energy-storage devices and as membranes for electrochemically controlled ion-exchange systems. In the present work, it is demonstrated that such composites with 42-72% porosity can be produced by using microfibrillated cellulose (MFC) prepared through enzymatic pretreatment or carboxymethylation, or by using different amounts of MFC in the composite synthesis. Together with previous work, this shows that the porosity of PPy/nanocellulose composites can be tailored from 30 to 98% with increments of similar to 10%. Employing the full porosity range of the composites, it is demonstrated that the electrochemical oxidation rate of the materials depends on their porosity due to limitations in the counter ion diffusion process. By tailoring the porosities of PPy/nanocellulose composites, the electrochemical properties can consequently be controlled. The latter provides new possibilities for the manufacturing of electrochemically controlled ion-extraction

  • 107.
    Cherepanova, Ekaterina
    et al.
    Luleå tekniska universitet.
    Hansson, Lars
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Determination of wood moisture properties using CT-scanner in a controlled environment2011Inngår i: Proceedings of the 7th meeting of the Nordic-Baltic Network in Wood Material Science and Engineering (WSE) / [ed] Erik Larnøy; Gry Alfredsen, Ås: Norsk institutt for skog og landskap , 2011, s. 137-142Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of the present work was to examine the existing algorithm for the moisture content calculation and also to use this algorithm to analyze and compare the moisture flow data for high and low temperature drying. The use of the existing algorithm for the dry weight moisture content on density data from the CT-scanning during high and low temperature drying in the climate chamber showed that this method is a powerful tool for analyzing the moisture flow inside the wood piece. Furthermore, the new CT-scanner together with the climate chamber gave unique results, as it has not been possible to study high temperature drying with this method before.

  • 108.
    Colic, Miodrag
    et al.
    Medical Faculty of the Military Medical Academy, University of Defense in Belgrade, Serbia.
    Mihajlovic, Dusan
    Medical Faculty of the Military Medical Academy, University of Defense in Belgrade, Serbia.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Naseri, Narges
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Kokol, Vanja
    University of Maribor, Institute for Engineering Materials and Design, Smetanova ul. 17, SI-2000 Maribor, Slovenia.
    Cytocompatibility and immunomodulatory properties of wood based nanofibrillated cellulose2015Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 1, s. 763-778Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose nanofibrils (CNFs), unique and promising natural materials have gained significant attention recently for biomedical applications, due to their special biomechanical characteristics, surface chemistry, good biocompatibility and low toxicity. However, their long bio-persistence within organisms may provoke chronic immune reactions and this aspect of CNFs has not been studied to date. Therefore, the aim of this work was to examine and compare the biocompatibility and immunomodulatory properties of CNFs in vitro. CNFs (diameters of 10-70nm; lengths of a few microns) were prepared from Norway spruce (Picea abies) by mechanical fibrillation and high pressure homogenisation. L929 cells, rat thymocytes or human peripheral blood mononuclear cells (PBMNCs) were cultivated with CNFs. None of the six concentrations of CNFs (31.25µg/ml – 1mg/ml) induced cytotoxicity and oxidative stress in the L929 cells, nor induced necrosis and apoptosis of the thymocytes and PBMNCs. Higher concentrations (250µg/ml – 1mg/ml) slightly inhibited the metabolic activities of the L929 cells as a consequence of inhibited proliferation. The same concentrations of CNFs suppressed the proliferation of PBMNCs to phytohemaglutinine, a T-cell mitogen, and the process was followed by down-regulation of interleukin-2 (IL-2) and interferon-γ (IFN-γ) production. The highest concentration of CNFs inhibited IL-17A but increased IL-10 and IL-6 production. The secretions of the inflammatory cytokines, IL-1β and the tumor necrosis factor-α (TNF-α) as well as Th2 cytokine (IL-4), remained unaltered. In conclusion, the results suggest that these CNFs are biocompatible, non-inflammatory and non-immunogenic nanomaterial. Higher concentrations seem to be tollerogenic to the immune system, a characteristic very desirable for implantable biomaterials.

  • 109.
    Correia, Viviane da Costa
    et al.
    Department of Biosystems Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo.
    Santos, Vlademir dos
    Department of Biosystems Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Santos, Sergio Francisco
    Department of Materials and Technology, Faculty of Engineering, São Paulo State University.
    Leão, Alcides Lopes
    Department of Rural Engineering, Sao Paulo State University.
    Junior, Holmer Savastano
    Department of Biosystems Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo.
    Grinding process for the production of nanofibrillated cellulose based on unbleached and bleached bamboo organosolv pulp2016Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 5, s. 2971-2987Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanofibrillated cellulose (NFC) is a type of nanomaterial based on renewable resources and produced by mechanical disintegration without chemicals. NFC is a potential reinforcing material with a high surface area and high aspect ratio, both of which increase reinforcement on the nanoscale. The raw materials used were unbleached and bleached bamboo organosolv pulp. Organosolv pulping is a cleaner process than other industrial methods (i.e. Kraft process), as it uses organic solvents during cooking and provides easy solvent recovery at the end of the process. The NFC was produced by treating unbleached and bleached bamboo organosolv pulps for 5, 10, 15 and 20 nanofibrillation cycles using the grinding method. Chemical, physical and mechanical tests were performed to determine the optimal condition for nanofibrillation. The delamination of the S2 layer of the fibers during nanofibrillation contributed to the partial removal of amorphous components (mainly lignin), which have low polarity and improved the adhesion of the fibers, particularly the unbleached cellulose. The transverse modulus of elasticity of the unbleached NFC was highest after 10 nanofibrillation cycles. Further treatment cycles decreased the modulus due to the mechanical degradation of the fibers. The unbleached NFC produced by 10 cycles have a greater transverse modulus of elasticity, the crystallite size showed increase with the nanofibrillation, and after 5 nanofibrillation cycles, no differences are observed in the morphology of the fibers.

  • 110.
    Couceiro, José
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wood shrinkage in CT-scanning analysis2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Computed tomography (CT) can be used to study wood-water interactions in differentways, such as by determining wood moisture content (MC). The determination of MCrequires two CT images: one at the unknown moisture distribution and a second one ata known reference MC level, usually oven-dry MC. The two scans are then compared.If the goal is to determine the MC in local regions, when studying moisture gradients forinstance, wood shrinkage must be taken into account during the data processing of theimages. The anisotropy of wood shrinkage creates an obstacle, however, since theshrinkage is not uniform throughout the wood specimen.

    The objective of this thesis was to determine the shrinkage in wood in each pixel of aCT image. The work explores two different methods that estimate from CT images, thelocal shrinkage of a wood specimen between two different MC levels. The first methoddetermines shrinkage for each pixel using digital image correlation (DIC) and isembedded in a wider method to estimate the MC, which is the parameter verifiedagainst a reference. It involves several steps in different pieces of software, making ittime-consuming and creating many sources of possible experimental errors. The MCdetermined by this method showed a strong correlation with the gravimetricallymeasured MC, showing an R2 of 0.93 and the linear regression model predicted MCwith a RMSE of 1.4 MC percentage points.

    The second method uses the displacement information generated from the spatialalignment of the CT images in order to compute wood shrinkage in the radial andtangential directions. All the required steps are combined into a single computeralgorithm, which reduces the sources of error and facilitates the process. The RMSEbetween this method and the determination of shrinkage measured in the CT imagesusing CAD has shown acceptable small differences.

    Both methods have proved to be useful tools to deal with shrinkage in different ways byusing CT images. In one case MC was successfully estimated, being the shrinkagecalculation a necessary step in the process, and in the other case the radial and tangentialshrinkages were successfully estimated for each pixel. Nevertheless, the difficulty incomparing the shrinkage coefficient calculated for local regions with a reference valuesuggest that more research must be carried out in order to be able to draw reliableconclusions.

  • 111. Cristescu, Carmen
    et al.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Changes in content of furfurals and phenols in self-bonded laminated boards2013Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, nr 3, s. 4056-4071Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressing beech veneers at high temperatures has been shown to be a reliable method for manufacturing laminated boards without adhesives. The reasons behind the self-bonding phenomenon as well as the causes of the waterproof character gained by the boards being pressed at 250 degrees C were investigated. Water leachates from the dried and the hot-pressed veneers were analysed by UV-spectroscopy, high-performance liquid chromatography (HPLC), and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR). Press-plate temperatures during hot pressing were 200, 225, and 250 degrees C. After pressing, an increased content of 5-(hydroxymethyl) furfural (not at 250 degrees C) and conjugated phenols was observed in the bonding lines (interfaces) compared to the inner part of veneers of the self-bonded boards. Furfural contents were low and relatively similar, but 5-(hydroxymethyl) furfural (HMF) showed an abrupt decrease in the bonding line when the temperature increased from 200 degrees C to 225 degrees C and especially to 250 degrees C. The contribution of caramelization to browning and bonding is suggested. In studies with CP/MAS 13C NMR, a higher content of phenolic units in beech lignin was observed during hot pressing at 225 degrees C. Homolytical cleavage of beta-O-4 structures in lignin as well as the condensation reactions involved are discussed

  • 112.
    Cristescu, Carmen
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Sandberg, Dick
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Ekevad, Mats
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Influence of pressing parameters on mechanical and physical properties of self-bonded laminated beech boards2015Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, nr 2, s. 205-214Artikkel i tidsskrift (Fagfellevurdert)
  • 113.
    Dagbro, Ola
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Spår i paneler: Delprojekt i det större projektet ”Sprickor i konstruktioner, utomhusexponering, optimering och simulering”2009Rapport (Annet (populærvitenskap, debatt, mm))
  • 114.
    Dagbro, Ola
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Studies on Industrial-Scale Thermal Modification of Wood2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Wood as a raw material is useful for many purposes even though some properties are less than optimal, for example, dimensional stability and durability. These characteristics can however be improved by different treatment methods. Environmental awareness has led to an increased demand for environmentally friendly processes like thermal modification that does not add any chemicals to the wood in contrast to, for example, CCA-impregnated wood.This thesis mainly focuses on thermally modified wood from species such as pine, spruce and birch. The thesis present studies of physical attributes such as color, and chemical analysis of water-soluble compounds and degradation products. Treatment intensity is compared between two different industrial processes referred as Thermowood and WTT, which use respectively superheated steam and pressurized steam as heating media.Thermal modification processes darken the color of wood throughout its cross-section. The formation of darker color is related to a degradation processes that takes place during thermal modification. During thermal modification wood is exposed to temperatures between 160 - 220°C, and the temperature causes physical and chemical transformations that change some of the wood properties. Dimensional stability and durability are typically improved, but mechanical strength properties are usually negatively affected by the treatment.The studied wood species were Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.) and Birch (Betula pendula L.). Treatments using pressurized steam were carried out under temperatures of 160°C, 170°C and 180°C, and treatments using superheated steam at normal air pressure were carried out at temperatures of 190°C and 212°C. Results showed that similar L* (lightness) can be reached at lower temperatures using pressurized steam compared to superheated steam. The residual moisture content after completed thermal modification was approximately 10% higher in wood treated with the pressurized steam process. It was found that despite an approximately 25°C lower treatment temperature, birch modified in pressurized steam was more acidic compared to birch modified in superheated steam. This will likely have further consequences, requiring more research concerning surface treatment and fixation.The thesis also includes the development of an industrial-quality control procedure based on nondestructive color measurements verified in industrial environment. Treatment intensity in industry is today certified by inspection of documented process schedule and measuring the temperature and time of the process. Quality control in this context refers to the measurement of wood color as an indirect measure of treatment intensity. The color in our study was measured using L*C*H color space. The study shows that it is possible for quality control purposes to measure the color of thermally modified wood from the surfaces of planed boards instead of sawdust or board cross sections that have been used in other studies.The thesis has a final section about academia-industry collaboration that describes how trust building was established through a fruitful relationship involving academia and regional wood products industry in northern Sweden. The study presents an example of a successful research and development alliance between university and a group of small- and medium-sized enterprises (SMEs). This alliance has been a great example on international collaboration involving researchers originating from Finland, China, Bangladesh, Spain, Russia and Sweden. Through an in-depth multi-year study of how the research cooperation developed, the paper describes how the involved companies successfully entered into a new segment of the market.

  • 115.
    Dagbro, Ola
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Torniainen, Petteri
    Department of Forest Products, Swedish University of Agricultural Sciences, Uppsala.
    Karlsson, Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Colour responses from wood, thermally modified in superheated steam and pressurized steam atmospheres2010Inngår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 5, nr 3, s. 211-219Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated steam (SS) and the other used pressurized steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20-308C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood was smaller for Norway spruce than for Scots pine. The residual moisture content was about 10% higher in wood treated by the PS process compared with the SS process

  • 116.
    Dagbro, Ola
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Torniainen, Petteri
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Thermal modification of birch using saturated and superheated steam2011Inngår i: Proceedings of the 7th meeting of the Nordic-Baltic Network in Wood Material Science and Engineering (WSE): October 27-28, 2011, Oslo, Norway / [ed] Erik Larnøy; Gry Alfredsen, Ås: Norsk institutt for skog og landskap , 2011, s. 43-48Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the thermal modification, wood is normally exposed to temperatures between 160 - 220°C. As a result physical and chemical changes are taking place and some of the wood properties are changed. Dimensional stability and weather resistance are improved. On the other hand the mechanical strength properties are usually negatively affected by the treatment. The visual appearance is also changed. There were two different types of thermal modification processes used in this study. One of them was using saturated steam and the other one superheated steam. Treatment temperature was 160°C in saturated steam process and 185°C in superheated steam. The wood specie used in this study was Silver birch (Betula pendula). In the chemistry part the acid content was investigated. Despite the 25°C lower treatment temperature, birch modified in saturated steam was more acidic compared to birch modified in superheated steam. Some differences in equilibrium moisture content (EMC) and dimensional stability were found mainly in the environment T=20°C and RH=85%. The colour of birch treated in saturated steam at 160°C was darker than the colour of birch treated in superheated steam at temperature 185°C.

  • 117.
    Danvind, Jonas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Analysis of drying wood based on nondestructive measurements and numerical tools2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Improved understanding of moisture and mechanical behaviour is a general objective for wood drying research. The main objective of this doctoral thesis was to develop nondestructive experimental methods suitable for collecting valuable response data related to the moisture behaviour and mechanical behaviour of drying wood and to refine this information into modelling parameters. A method for simultaneous noncontact measurement of two-dimensional surface deformations and interior densities was developed. This was done using Digital Speckle Photography (DSP) and X-ray Computed Tomography (CT). Displacements and densities were used for calculation of strain and of moisture content. Experimental tests of the measurement method were done on cross sections of Scots pine. The following accuracy was stated for different properties: A typical calculated displacement error of approximately 10 micrometre was found. Strains derived from the displacements had a maximal error of 1.11 mstrain. Moisture content measuring accuracy was estimated to +-1.8% moisture content at a significance level of 0.05 in a measuring volume with the approximate size 2 x 2 x 1.5 mm3. A similar noncontact technique based only on X-ray CT scanning was developed. Displacements were then estimated from boundary movements of an object in CT images. The estimated standard deviation of the measured moisture content error for this method was 0.04% moisture content. The mean error was unknown. Two different approaches to determining moisture diffusion coefficients from the studied data were presented. The first was based on minimizing the difference between measured and computed values through an optimization scheme. This approach required an initial assumption of the functional form of the diffusion coefficient. The second approach calculated diffusion and mass transfer coefficients through direct finite difference calculations on measured moisture content data. Results on Norway spruce showed interesting local variations of the diffusion coefficient, especially near the evaporation surface. Comparisons between measured and FEM simulated data showed good results. An example showed that a multivariate method of analysis could be an effective and easy-to-use tool for untangling relationships between variables and for generating information from data. Finally, it could be stated that the methods presented will be of use to improve the understanding of the behaviour of drying wood, with the focus on moisture and mechanical properties.

  • 118. Danvind, Jonas
    Measuring strain and moisture content in a cross section of drying wood using Digital Speckle Photography and Computerised X-ray Tomography2003Inngår i: Proceedings of the 13th International Symposium on Nondestructive Testing of Wood: August 19-21, 2002, University of California, Berkeley Campus, California, USA / [ed] Frank C. Beall, Madison, Wis.: Forest Products Society, 2003Konferansepaper (Fagfellevurdert)
  • 119.
    Danvind, Jonas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Methods for collecting and analysing simultaneous strain and moisture data during wood drying2002Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Improved understanding of moisture and mechanical behaviour is an international objective for wood drying research. The main objective of this licentiate thesis work was to develop an experimental method suitable for collecting valuable response data related to the moisture and mechanical behaviour of drying wood. Another objective was to provide an example on how multivariate methods can be used to analyse response data. A method for simultaneous non contact measuring of two dimensional surface deformations and interior densities have been developed. This was done using Digital Speckle Photography, DSP, and X-ray Computerised Tomography (CT). Displacements and densities were used for calculation of strains and moisture contents using a custom software developed in Matlab. Experimental tests of the measuring method were made on cross sections of Scots pine. The following accuracy was stated for different properties: - Displacements measured with DSP could be measured with a random error down to 0.01 pixels. A more typical calculated displacement error of approximately 10 micrometres, was found in paper I. - Strains derived from the displacements had a maximal error of 1.11 mstrain in an experimental test in paper II. - Accuracy in density measurements was expected to be less than +-6 kg/m3 for wet wood with moisture contents ranging from 6-100% and less than +-2 kg/m3 in dry wood, at a significance level of 0.05. This was estimated for a 2x2x1.5 mm3 measuring volume. - Moisture content measuring accuracy was estimated by simulations in paper II, which resulted in a measuring accuracy of +-1.8% moisture content at a significance level of 0.05 in a measuring volume with the approximate size of 2x2x1.5 mm3. A multivariate analysing method has been used to present an example on multivariate modelling of shrinkage behaviour in Radiata pine. The method was found to be an easy-to-use tool and useful for valid prediction of radial, tangential, longitudinal and volume shrinkage in the moisture range between 0% and 22% moisture content of the studied wood. The method also proved to be effective for untangling relationships between variables and generating information out of data. Finally, it can be stated that the developed measuring technique and the tested multivariate analysing method will be of use to improve the understanding of the behaviour of drying wood, focusing on moisture and mechanical properties.

  • 120.
    Danvind, Jonas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    PLS prediction as a tool for modeling wood properties2002Inngår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 60, nr 2, s. 130-140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During an earlier study, material responses of shrinkage and deformation during air-drying were measured on small wood specimens cut from the cross section of a Pinus radiata log. In this paper the analysis of the collected data and the modeling of studied responses were done using multivariate methods. A first model with all variables and all 104 observations was created. In this model there were observations that deviated from the rest and some of them were therefore excluded from further modeling. Also, weak variables and undesired variables were excluded from further modeling. After these exclusions, 77 observations of wood responses below fiber saturation point remained. The results showed good modeling of radial, tangential and volumetric shrinkage between 0-22% MC, with explained variance (R2) and predicted variance (Q2) at approximately 0.9, and moderate modeling of longitudinal shrinkage, R2 = 0.67 and Q2 = 0.65. It was also shown that longitudinal shrinkage has weak correlation to density-related variables in the studied wood. No model with good predictability of deformation was found. This study showed that PLS prediction modeling of shrinkage and deformation in studied wood samples was found to be an effective and easy-to-use tool for untangling relationships between variables and generating information from data.

  • 121.
    Danvind, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Ekevad, Mats
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Local water vapor diffusion coefficient when drying Norway spruce sapwood2006Inngår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 52, nr 3, s. 195-201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, a one-dimensional and a two-dimensional approach to the evaluation of local diffusion coefficients for Norway spruce sapwood from measured moisture content (MC) values are presented. A studied wood sample was dried from the initial green condition to about 15% mean MC, but here only the diffusive part of the drying process between approximately 25% and 15% mean MC was treated. Measured local MC values were based on nondestructive X-ray computed tomography data. Finite element calculations were performed with two alternative diffusion coefficients to test the appropriateness of the diffusion coefficients that were evaluated from the measured MC values. The evaluated diffusion coefficients show interesting dependence on MC and distance from the evaporation surface. The advantage of using the methods presented is that the diffusion coefficient is calculated on a local level without having to define a function for the diffusion coefficient's dependency on other parameters

  • 122.
    Danvind, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Eriksson, John
    Johansson, Håkan
    Calibration of a constitutive model for diffuse moisture transport in wood using data from X-ray CT-scanning and digital speckle photography2004Konferansepaper (Fagfellevurdert)
  • 123. Danvind, Jonas
    et al.
    Morén, Tom
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Using X-ray CT scanning for moisture and displacement measurements in knots and their surroundings2004Konferansepaper (Fagfellevurdert)
  • 124.
    Danvind, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Synnergren, Per
    Method for measuring the shrinkage behaviour of drying woods using digital speckle photography and x-ray computerised tomography2001Inngår i: Moisture control in environment-friendly housing and wood drying technology in new century: July 9-13, 2001 Tsukuba, Japan / [ed] K. Hayashi, Ibaraki: Forestry and Forest Products Research Institute , 2001, s. 276-281Konferansepaper (Fagfellevurdert)
  • 125.
    Das, Oisik
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Kim, Nam Kyeun
    Centre for Advanced Composite Materials, Department of Mechanical Engineering, The University of Auckland, Auckland,New Zealand.
    Hedenqvist, Mikael S.
    Department of Fibre and Polymer Technology, Polymeric Materials division, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden.
    Bhattacharyya, Debes
    Centre for Advanced Composite Materials, Department of Mechanical Engineering, The University of Auckland, Auckland, New Zealand.
    Johansson, Eva
    Department of Plant Breeding, Faculty of Landscape Planning, Horticulture and Crop Production Sciences, Swedish University of Agricultural Sciences, Alnarp, Sweden.
    Xu, Qiang
    School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, China.
    Holder, Shima
    Department of Fibre and Polymer Technology, Polymeric Materials division, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden.
    Naturally-occurring bromophenol to develop fire retardant gluten biopolymers2020Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 243, artikkel-id 118552Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the study was to impart fire retardancy in wheat gluten polymer through naturally-occurring additives such as lanosol. The fire properties of lanosol were compared with two other conventional brominated fire retardants (Tetrabromobisphenol A and Hexabromocyclododecane). Samples containing fire retardants and gluten were prepared through compression moulding process and then characterised for their fire and mechanical properties. All fire retardants enhanced the reaction-to-fire and thermal properties of gluten while generating V-0 (i.e. vertical position and self-extinguished) ratings in the UL-94 test. The presence of all the fire retardants increased the modulus of the gluten polymer but the fire retardant particles were detrimental for the tensile strength. Nevertheless, lanosol addition delayed ignition and lowered peak heat release rate of gluten by the maximum amount, thereby leading to relatively higher fire performance index (compared to the other fire retardants). Lanosol also allowed the gluten to create a dense char barrier layer during burning that impeded the transfer of heat and flammable volatiles. The fact that only 4 wt% lanosol was able to cause self-extinguishment under direct flame and reduce peak heat release rate by a significant 50% coupled with its inherent occurrence in nature, raises the question if lanosol can be a potential fire retardant in polymeric systems, although it is a bromophenol.

  • 126.
    Davoodi, M.M.
    et al.
    Universiti Putra Malaysia 43400 UPM Serdang, Selangor.
    Sapuan, S.M.
    Universiti Putra Malaysia 43400 UPM Serdang, Selangor.
    Ahmad, D.
    Universiti Putra Malaysia 43400 UPM Serdang, Selangor.
    Aidy, A.
    Universiti Putra Malaysia 43400 UPM Serdang, Selangor.
    Khalina, A.
    Universiti Putra Malaysia 43400 UPM Serdang, Selangor.
    Jonoobi, Mehdi
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Concept selection of car bumper beam with developed hybrid bio-composite material2011Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 32, nr 10, s. 4857-4865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Application of natural fibre composites is going to increase in different areas caused by environmental, technical and economic advantages. However, their low mechanical properties have limited their particular application in automotive structural components. Hybridizations with other reinforcements or matrices can improve mechanical properties of natural fibre composite. Moreover, geometric optimizations have a significant role in structural strength improvement. This study focused on selecting the best geometrical bumper beam concept to fulfill the safety parameters of the defined product design specification (PDS). The mechanical properties of developed hybrid composite material were considered in different bumper beam concepts with the same frontal curvature, thickness, and overall dimensions. The low-speed impact test was simulated under the same conditions in Abaqus V16R9 software. Six weighted criteria, which were deflection, strain energy, mass, cost, easy manufacturing, and the rib possibility were analyzed to form an evaluation matrix. Topsis method was employed to select the best concept. It is concluded that double hat profile (DHP) with defined material model can be used for bumper beam of a small car. In addition, selected concept can be strengthened by adding reinforced ribs or increasing the thickness of the bumper beam to comply with the defined PDS.

  • 127.
    Davoodi, M.M.
    et al.
    Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia.
    Sapuan, S.M.
    Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia.
    Ahmad, D.
    Department of Biological and Agricultural Engineering, Universiti Putra Malaysia.
    Aidy, A.
    Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia.
    Khalina, A.
    Department of Biological and Agricultural Engineering, Universiti Putra Malaysia.
    Jonoobi, Mehdi
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Effect of polybutylene terephthalate (PBT) on impact property improvement of hybrid kenaf/glass epoxy composite2012Inngår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 67, nr 1, s. 5-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Environmental regulations, costs and lightweight encourage car manufacturers to develop new reliable products. Epoxy provides a reliable fibre impregnation and creates substantial three-dimensional (3D) cross-linking for proper load transmission and impact strength improvement, but their low toughness decreases their energy absorption. Thermoplastic toughening improves the epoxy impact property with a low thermo-mechanical defect. This study, focused on improving the impact property of hybrid kenaf/glass fibre epoxy composite by use of a modified sheet moulding compound (GMT). The results indicated that most of the mechanical properties of developed material were almost the same as those of the GMT, except impact. This result highlights the potential for utilisation of the toughened hybrid bio-composite in some automotive structural components. Moreover, geometric parameters, e.g., cross-section, thickness, and reinforcement ribs suggest an improvement of structural impact resistance to comply with the bumper beam product design specification (PDS).

  • 128.
    Deepa, B.
    et al.
    Department of Chemistry, Bishop Moore College, Mavelikara, 690101, Kerala.
    Abraham, Eldho
    Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University, Jerusalem.
    Cordeiro, Nerida
    Competence Centre in Exact Science and Engineering, University of Madeira.
    Mozetic, Milan
    Department of Surface Engineering, Jozef Stefan Institute.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Faria, Marisa
    Competence Centre in Exact Science and Engineering, University of Madeira.
    Thomas, Sabu
    Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, Department of Chemistry, C.M.S. College, Kottayam, 686001, Kerala.
    Pothan, Laly A.
    Department of Chemistry, Bishop Moore College, Mavelikara, 690101, Kerala.
    Utilization of various lignocellulosic biomass for the production of nanocellulose: a comparative study2015Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 2, s. 1075-1090Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nanocellulose was successfully extracted from five different lignocellulosic biomass sources viz. banana rachis, sisal, kapok, pineapple leaf and coir using a combination of chemical treatments such as alkaline treatment, bleaching and acid hydrolysis. The shape, size and surface properties of the nanocellulose generally depend on the source and hydrolysis conditions. A comparative study of the fundamental properties of raw material, bleached and nanocellulose was carried out by means of Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, birefringence, X-ray diffraction, inverse gas chromatography and thermogravimetric analysis. Through the characterization of the nanocellulose obtained from different sources, the isolated nanocellulose showed an average diameter in the range of 10–25 nm, high crystallinity, high thermal stability and a great potential to be used with acid coupling agents due to a predominantly basic surface. This work provides an insight into the effective utilization of a variety of plant biomass as a potential source for nanocellulose extraction.

  • 129. Deepalakshmi, P
    et al.
    Visakh, P M
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Chandra, Arup K.
    Thomas, Sabu
    Advances in elastomers: Their composites and nanocomposites: State of art, new challenges and opportunities2013Inngår i: Advances in elastomers II: Composites and nanocomposites, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2013, s. 1-9Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The field of elastomers, their composites and nanocomposites has gained a lot of interest in recent years. These composite materials have great significance both from the fundamental and application point of view. Since this field is growing at a faster rate, it is always necessary to address the structure, properties and applicability of such materials. The present chapter gives a brief account on various elastomer systems, their composites and nanocomposites. Various topics such as elastomer based macrocomposites, nanocomposites, interphase modification, compatiblisation of rubber based nanocomposites, fully green elastomer nanocomposites, elastomeric micro and nanocomposites for tyre applications, elastomer based bionanocomposites, bio-medical applications of elastomeric composites and nanocomposites have been very briefly discussed. Finally the applications, new challenges and opportunities of these composites and nanocomposites are also discussed.

  • 130. Duchemin, Benoit
    et al.
    Mathew, Aji P.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    All-cellulose composites by partial dissolution in the ionic liquid 1-butyl-3-methylimidazolium chloride2009Inngår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 40, nr 12, s. 2031-2037Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fully bio-based and biodegradable all-cellulose composites were prepared in the form of films by partial dissolution of two cellulose sources: a commercially available microfibrillated cellulose (MFC) and filter paper (FP). The solvent selected for this work was the ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl). Both cellulose sources were partially dissolved at 80 °C and consolidated by partial dissolution, resulting in excellent mechanical properties. X-ray diffraction and electron microscopy demonstrated that partial dissolution was a viable path to transform FP into a continuous paracrystalline matrix reinforced with cellulose I crystallites. In contrast, partially dissolved MFC was not as thoroughly dissolved and large amounts of undissolved material were still visible along the center line of the films after the longest dissolution times. Consequently, partially dissolved MFC retained its initially high crystallinity. The degree of polymerization of the materials after dissolution was significantly reduced.

  • 131. Duchemin, Benoit
    et al.
    Mathew, Aji P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Green ionic liquids for the production of fully-biobased and biodegradable all-cellulose nanocomposites2010Inngår i: 10th International Conference on Wood & Biofiber Plastic Composites and Cellulose NanoComposites Symposium, Forest Products Society, 2010Konferansepaper (Fagfellevurdert)
  • 132.
    Duncombe, Bridgette J
    et al.
    Department of Physical Chemistry, School of Chemistry, University of Nottingham.
    Ryden, Jens
    Department of Chemistry, University of Sussex, Falmer, Brighton.
    Puškar, Ljiljana
    Department of Chemistry, University of Sussex, Falmer, Brighton.
    Cox, Hazel L.
    Department of Chemistry, University of Sussex, Falmer, Brighton.
    Stance, Anthony J.
    Department of Physical Chemistry, School of Chemistry, University of Nottingham.
    A Gas-Phase Study of the Preferential Solvation of Mn2+ in Mixed Water/Methanol Clusters2008Inngår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 19, nr 4, s. 520-530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The kinetic shift that exists between two competing unimolecular fragmentation processes has been used to establish whether or not gas-phase Mn2+ exhibits preferential solvation when forming mixed clusters with water and methanol. Supported by molecular orbital calculations, these first results for a metal dication demonstrate that Mn2+ prefers to be solvated by methanol in the primary solvation shell.

  • 133.
    Elustondo, Diego
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknologi.
    Guest Editorial: R&D Needs in Wood Drying Technology2014Inngår i: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, nr 6, s. 629-630Artikkel i tidsskrift (Annet vitenskapelig)
  • 134.
    Elustondo, Diego
    FPInnovations-Wood Products, Vancouver, British Columbia.
    The wrong assumption: revolutionary scientific theories that shape the elusive supernatural world2012Bok (Fagfellevurdert)
    Abstract [en]

    The Wrong Assumption: Revolutionary Scientific Theories That Shape the Elusive Supernatural World provides a scientific approach to philosophical thinking and encourages readers to explore their spiritual beliefs. By using simple language and honest scientific rigor, this e-book illuminates fascinating and revolutionary scientific theories that provide physical shape to the otherwise elusive concept of the supernatural world. Readers are exposed to a large variety of scientific theories that justify the existence of spiritual beliefs. Unlike other similar books that explore the connection between science and religion, this e-book refrains from manipulating science to fit a particular dogma; rather, it highlights scientific concepts remarkably similar to those ideas traditionally associated with spiritual beliefs. This e-book condenses the scientific knowledge that is currently dispersed throughout many books into a reader friendly volume.

  • 135.
    Elustondo, Diego
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Ahmed, Sheikh Ali
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Oliveira, Luiz
    Department of Lumber Manufacturing, FPInnovations, Vancouver.
    Drying Western Red Cedar with Superheated Steam2014Inngår i: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 32, nr 5, s. 550-556Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This exploratory study evaluated the possibility of drying 50-mm-thick western red cedar with superheated steam. Since there are no industrial facilities in Canada drying western red cedar with superheated steam, the study was designed to explore the potential of this technology in terms of lumber quality, moisture content distribution, and drying time. The experiments showed that the 50-mm-thick product can be dried in less than three days without jeopardizing lumber quality (in comparison with the two weeks that is currently required in conventional kilns), and the percentage of pieces that remained wet after drying was within the 10% to 15% range that is typically tolerated in industry.

  • 136.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Modeling a timber "dry/sort/re-dry" strategy using combined conventional and dielectric technologies2002Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work, a numerical stochastic model is presented and utilized to study the dry/sort/re-dry (DSRD) strategy for 116-mm square ,timbers ,by using ,combined conventional,and ,radio frequency ,vacuum ,(RFV) drying ,technologies. The model parameters are calibrated with experimental timber drying data of mixed western hemlock and amabilis fir, and the total percentages of on-grade, over-dried and under-dried timbers are simulated for different conventional and RFV target moisture content situations. The results of the simulated percentages of timbers are presented in 2-D level curves, and the ranges of target that should be used ,in order ,to obtain ,maximum ,on-grade timbers are analyzed.

  • 137.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Simulated comparative analysis of sorting strategies for RFV drying2003Inngår i: Wood and Fiber Science, ISSN 0735-6161, Vol. 35, nr 1, s. 49-55Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a numerical stochastic model is used to compare three possible sorting strategies in radio frequency vacuum (RFV) drying of thick timbers, namely, moisture content based pre-sorting (MCPS), batch dry/sort/redrying (b-DSRD) and continuous or retro-feed dry/sort/redry (c-DSRD). The model parameters were calibrated with experimental data of western hemlock dried in a commercial RFV dryer, and the results of the simulations were compared to a single pass base case (SPBC). The numerical results clearly demonstrated the differences among these strategies. The MCPS showed no significant improvement in final timber quality as defined by average timber moisture content, but there is an evident improvement in both b-DSRD and c-DSRD. The comparison was based on the increment of the percent of the on-grade wood (within moisture content range) and the reduction of overdried and underdried (wets) percentages. Furthermore, it was also shown that the effective drying time is roughly independent of the drying strategy

  • 138.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Stochastic numerical model for radio frequency vacuum drying of timbers2002Inngår i: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 20, nr 9, s. 1827-1842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new numeric method to simulate stochastic dispersion (a natural phenomenon that occurs when a magnitude cannot be associated to a specific value, but to the probability of being within a range of values) is proposed and applied to predict Radio Frequency Vacuum (RFV) drying of timber. A theoretical formulation of the method is described and complemented to take into account the frequency distribution of the timber initial moisture content, so that it can be applied to industrial runs. Experimental data obtained from mixed western hemlock and amabilis fir dried in a commercial RFV kiln are used to validate the stochastic model, and the results are compared through moisture content histograms and probability charts. A numerical example is shown in order to provide an idea of the movement of the moisture profiles during RFV drying.

  • 139.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    The demonstration of increased lumber value using optimized lumber sorting2004Konferansepaper (Fagfellevurdert)
  • 140.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    University of British Columbia, Department of Wood Science.
    Oliveira, Luiz C De S
    Forintek Canada Corporation, Western Laboratory, Vancouver, BC.
    Industrial evaluation of re-dry stragegy for softwood lumber2005Inngår i: MADERAS: Ciencia y Tecnología, ISSN 0717-3644, E-ISSN 0718-221X, Vol. 7, nr 2, s. 65-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents an experimental evaluation of the first commercial scale dry-sort-redry (DSRD) strategy for drying of 2x4 Pacific coast hemlock (PCH) lumber. The DSRD strategy is a methodology designed to reduce final moisture content variability in kiln dried lumber by complementing conventional drying with radio frequency vacuum (RFV) drying technology. The strategy′s objective is to avoid producing over-dried lumber in conventional drying by setting the target moisture content to a value much higher than those usually used in industry. Then, RFV drying technology is implemented to quickly and efficiently re-dry the lumber that remains wet (under-dried) after the first conventional pass. Six experimental tests were performed in an industrial sawmill with the intention of studying the effect of target moisture content on the properties and quality of the dried lumber. In all cases, the first drying pass was performed in a 260m3 industrial heat-and-vent conventional kiln, and the re-drying of wets was performed in a 75m3 RFV kiln. Additionally, a mathematical model developed for prediction of data dispersion in lumber drying was calibrated with experimental data, and used to simulate the DSRD strategy under other hypothetical conditions. The results of the study demonstrate that the DSRD strategy reduces drying time, shrinkage and kiln drying degrade in comparison with a single conventional pass.

  • 141.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Zwick, Robert L.
    HeatWave Technologies Inc.
    The demonstration of increased fiber utilization using optimized lumber sorting and radio-frequency vacuum drying2003Konferansepaper (Fagfellevurdert)
  • 142.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avrimidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Stochastic numerical model for conventional kiln drying of timbers2003Inngår i: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 49, nr 6, s. 485-491Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A numerical model that predicts the stochastic dispersion associated with industrial kiln drying of timber was adapted to conventional drying and evaluated with experimental data. The theoretical aspects of the model are briefly explained, a selection of the calibration parameters was carried out, and a new empirical dispersion factor is proposed to account for all unknown sources of random behavior. The model was calibrated with six experimental runs of western hemlock and amabilis fir (116 mm2 timbers) to an average moisture content (target) of 14%-20%. It was found that with implementation of the dispersion factor, the number of required simulations is considerably reduced, the calibration results are consistent for all the experimental runs, and the target moisture content along with its standard deviation can be well reproduced using the all-run average parameters.

  • 143.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avrimidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Shida, Satoshi
    Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo.
    Predicting thermal efficiency in timber radio frequency vacuum drying2004Inngår i: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 22, nr 4, s. 795-807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, the efficiency of transforming dielectric energy into evaporated water is analyzed for the case of timber radio frequency vacuum drying. Based on well-known heat and mass transfer equations, a simplified mathematical model is proposed that estimates the drying efficacy in regards to the thermo-physical properties of wood. Although not exact, the theoretical results are close to the experimental observations and elucidate some phenomena like the tendency of the timber to dry from inside to outside, and the drying rate increase with the rise of the timber gas permeability. The theoretical efficiency model also predicts a range of wood permeability values for which the drying efficiency changes from 100 to 0%, thus providing a quantitative scale for classifying the spectrum of "difficult-to-dry" all the way to "easy-to-dry" wood species when using radio frequency vacuum technology

  • 144.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avrimidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Zwick, Robert L.
    HeatWave Technologies Inc.
    The demonstration of increased lumber value using optimized lumber sorting and radio frequency vacuum drying2005Inngår i: Forest products journal, ISSN 0015-7473, Vol. 55, nr 1, s. 76-83, artikkel-id 9759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents an experimental evaluation of the first commercial scale dry/sort/re-dry (Q-Sift®) strategy for drying of 2 by 4 Pacific Coast hemlock lumber using combined conventional and radio frequency vacuum drying technologies. The strategy was evaluated through six experimental tests in which lumber loads were dried to different final average moisture content in an industrial heat-and-vent conventional kiln, and measured for initial and final moisture content distribution, shrinkage, and drying degrade. Additionally, a stochastic model especially developed for this strategy was calibrated with the measured data and used to simulate the results of the strategy under different drying conditions within the calibration range. The study demonstrated that the implementation of the Q-Sift strategy decreases the process drying time, and reduces shrinkage and kiln-drying degrade in comparison with a single conventional pass. An economic model was also developed in order to determined the industrial viability of the method, and for the studied industrial case it was demonstrated that the revenues of the new strategy allow an investment payback in less than 1.5 years.

  • 145.
    Elustondo, Diego
    et al.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Elustondo, Miguel P.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Urbicain, Martin J.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Drying of foodstuff with superheated steam: maximum rate as function of pressure2000Inngår i: Proceedings of the 12th International Drying Symposium, IDS 2000: 28 - 31 August 2000, Noordwijkerhout, The Netherlands ; [also includes the Mini-Symposium on Advances in Paper Dewatering (AIPD 2000)] / [ed] P.J.A.M. Kerkhof, New York: Elsevier, 2000Konferansepaper (Fagfellevurdert)
  • 146.
    Elustondo, Diego
    et al.
    Universidad Nacional del Sur, Camino La Carrindanga.
    Elustondo, Miguel P.
    Universidad Nacional del Sur, Camino La Carrindanga.
    Urbicain, MArtin J.
    Universidad Nacional del Sur, Camino La Carrindanga.
    Drying with superheated steam: Maximum drying rate as a linear function of pressure2002Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 86, nr 1-2, s. 69-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Drying with superheated steam (SS) as heating agent is controlled through three operative variables, the steam temperature, the recycle velocity, and the system pressure. Once the other conditions are fixed, there is an optimum pressure at which drying rate reaches its maximum value. The exact optimum conditions can be found through a differential mass and energy balance over the heat exchange area, resulting in two equations. The first one to calculate the drying rate as function of the operating conditions and the second one to find the values of those conditions which make the operation optimum. Then, using these equations, this paper shows that the relationship between maximum drying rate and pressure can be rewritten in a unique linear equation. Experiments were performed in a model system to obtain a family of drying rates versus pressure curves, and in accordance with the predicted behaviour, it was observed that all maximum drying rates lay on a straight line

  • 147.
    Elustondo, Diego
    et al.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Elustondo, Miguel P.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Urbicain, Martin J.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Mathematical modeling of moisture evaporation from foodstuffs exposed to subatmospheric pressure superheated steam2001Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 49, nr 1, s. 15-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a reduced expression to calculate the drying rate of foodstuffs being dried with low pressure superheated steam is developed. It is based on a theoretical drying mechanism which assumes that water removal is carried out by evaporation in a moving boundary making the vapor to flow through the dry layer built as drying proceeds. The theoretical model can be applied to any form and features dimensionless parameters to allow for the influence of form, shrinking effect and boiling point rise. To make the application easier, a simplified expression was derived, which has only two experimentally determined parameters and allows the calculation of the drying rate of a given product. Different foodstuffs were dried with this technique and the empirical parameters were calculated from the experimental data fitting equation. Interestingly, those parameters can be considered constant within the 10000-20000 Pa pressure range and the 60-90°C temperature range

  • 148.
    Elustondo, Diego
    et al.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Elustondo, Miguel P.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    Urbicain, Martin J.
    Planta Piloto De Ingeniería Química (UNS-CONICET), C. C. Km 7, 12 Oct. 1842, C.C. 717, (8000), Bahía Blanca.
    New thermal conductivity probe design based on the analysis of error sources2001Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 48, nr 4, s. 325-333Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The thermal conductivity determination by means of the thermal probe is a classical non-stationary method, suitable for foodstuffs because of the relatively short period of time and the small temperature rise required during experimental measurements. Even though its simplicity, this method has theoretical and practical implicit errors, their main sources being evaluated in this paper. The theoretical analysis shows that experimental errors can be kept within acceptable values, if the testing time period is within certain limits, out of which the errors grow quite rapidly. The error arising from the calculation of the thermal conductivity by means of an approximate equation is studied and a new way to express it is presented. Also, testing times were calculated for different probe dimensions. Finally, on the basis of two former probe which exhibits some advantages upon each other, a new probe design is proposed which recoveries those features.

  • 149.
    Elustondo, Diego
    et al.
    Department of Wood Science, University of British Columbia, Vancouver.
    Koumoutsakos, Anastasios D.
    Department of Wood Science, University of British Columbia, Vancouver.
    Avramidis, Stavros H.
    Department of Wood Science, University of British Columbia, Vancouver.
    Non-deterministic description of wood radio frequency vacuum drying2003Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 57, nr 1, s. 88-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A numerical method is proposed to predict the stochastic dispersion of data that unavoidably occurs in a real drying process. The method is based on the use of discrete frequency distribution curves to predict a random variation on some parameters of the process and is applied to the case of radio frequency vacuum (RFV) drying of wood. Experimental data of RFV drying of western hemlock timbers were used to obtain the numeric values of the stochastic parameters and their standard deviation. A mathematical model was designed to simulate the final moisture content dispersion on hypothetical examples. Results were quantified using three indices: average, range and standard deviation.

  • 150.
    Elustondo, Diego
    et al.
    PLAPIQUI (UNS-CONICET), Camino La Carrindanga Km 7.
    Mujumdar, Arun Sadashiv
    PLAPIQUI (UNS-CONICET), Camino La Carrindanga Km 7.
    Urbicain, Martin J.
    Department of Mechanical Engineering, National University of Singapore.
    Optimum operating conditions in drying foodstuffs with superheated steam2002Inngår i: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 20, nr 2, s. 381-402Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is inferred from experimental data that in drying foodstuffs with superheated steam, the initial drying rate has a direct effect on the rate at which the overall drying takes place. That is, the faster the initial drying rate, the shorter the overall drying time. This criterion is very convenient because at the beginning, water moistens the sample external surface so evaporation does not depend on internal sample characteristics, but only on external convective heat and mass transfer rates. Mass and energy balance equations are solved and the result converted into a general initial drying rate equation, in which all dryer characteristics are grouped into one dimensionless parameter. The initial drying rate equation is mathematically maximized and the optimum working conditions determined. The result shows that initial drying rate always increase with increases of either the superheated steam temperature or velocity, but once these two variables are fixed, there exists at least one "optimum" pressure at which the initial drying rate is a maximum. Finally, the initial drying rate and optimum condition equations are applied to three model dryers, a dryer for a flat sheet, a fixed bed dryer and a rotary dryer. In each case, numeric values are computed and plotted as drying rate versus pressure curves, in which the optimum drying rate is also included. Also presented is a chart to compare the optimum pressures as functions of temperature and steam velocity for the three dryers.

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