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The exterior application of fire-retardant (FR) timber necessitates it to have high durability because of the possibility to be exposed to rainfall. In this study, water-leaching resistance of FR wood has been imparted by grafting phosphate and carbamate groups of the water-soluble FR additives ammonium dihydrogen phosphate (ADP)/urea onto the hydroxyl groups of wood polymers via vacuum-pressure impregnation, followed by drying/heating in hot air. A darker and more reddish wood surface was observed after the modification. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid-state 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (13C CP-MAS NMR), and direct-excitation 31P MAS NMR suggested the formation of C–O–P covalent bonds and urethane chemical bridges. Scanning electron microscopy/energy-dispersive X-ray spectrometry suggested the diffusion of ADP/urea into the cell wall. The gas evolution analyzed by thermogravimetric analysis coupled with quadrupole mass spectrometry revealed a potential grafting reaction mechanism starting with the thermal decomposition of urea. Thermal behavior showed that the FR-modified wood lowered the main decomposition temperature and promoted the formation of char residues at elevated temperatures. The FR activity was preserved even after an extensive water-leaching test, confirmed by the limiting oxygen index (LOI) and cone calorimetry. The reduction of fire hazards was achieved through the increase of the LOI to above 80%, reduction of 30% of the peak heat release rate (pHRR2), reduction of smoke production, and a longer ignition time. The modulus of elasticity of FR-modified wood increased by 40% without significantly decreasing the modulus of rupture. Validerad;2023;Nivå 2;2023-04-21 (joosat);Funder: OP RDE (Grant no.CZ.02.1.01/0.0/0.0/16_019/0000803); CT WOOD, Luleå University of TechnologyLicens fulltext: CC BY License

Chemical modification of wood typically requires the impregnation of wood with reactive compounds capable of undergoing covalent bonding to functional groups present in the cell wall. Creating such reactive agents in situ, with the use of low-priced chemicals, would prove more attractive for commercial applications. In this study, Scots pine (Pinus sylvestris L.) sapwood was impregnated with an aqueous solution of urea (30%), dried at 40°C for 24 h, and subsequently heat treated in an oven at 150°C for 24 h to produce the reactive isocyanic acid. By using accelerated fungal tests under laboratory conditions, provisional tests demonstrated a high biological resistance against selected moulds and rots. Migration of urea into the wood structure and grafting to its polymers during subsequent heat treatment, led to a bulked cell wall and enhanced resistance to water swelling, even after cycling water treatments. The bending strength (MOR) of modified pine wood was reduced by the treatment applied, while its modulus of elasticity (MOE) remained unchanged. Validerad;2023;Nivå 2;2023-06-30 (joosat);Licens fulltext: CC BY-NC-ND License Biobased fire protection of wood panel for exterior conditions by using phosphorylated lignin from wheat straw

Wood composites are manufactured by joining wood fibres, strands, or particles together with an adhesive, but it is necessary for eliminate the use of formaldehyde-based adhesives in the manufacture of wood composites for the sake of indoor air quality and human health. This initial study has demonstrated the use of sorbitol and citric acid as a potential bio-based formaldehyde-free adhesive for wood-composite manufacture. A solution of citric acid and sorbitol in water was sprayed onto wood particles which were then pressed at 160°C, 180°C, or 200°C for 13 min, to produce boards with a target thickness of 8 mm. The FTIR spectra contained an absorption band at 1720cm−1, presumably due to the esters of citric acid and sorbitol. Pressing of a temperature of 200°C gave boards with the highest modulus of elasticity and the highest internal bond strength. The results reveal a new potential bio-adhesive for the manufacture of wood composites. Validerad;2022;Nivå 2;2022-11-25 (hanlid);Funder: OP RDE (CZ.02.1.01/0.0/0.0/16_019/0000803); Swedish wood industry CT WOOD

Brown discolouration caused by resin exudation from knots is a problem for a range of light-coloured painted pines, and will negatively affect the appearance of the finish. To solve this problem, a hot-and-cold bath impregnation process of wood prior to painting was tested. Sawn timber, 18 × 120 mm in cross-section dimension, were heated in an oven and then immediately immersed in a cold liquid containing a phenol-formaldehyde-based solution, filling a 1–5 mm thick layer beneath the surface with phenol-formaldehyde. After curing, the timbers were painted with a white coloured coating system intended for exterior use, and tested in artificial weathering test (QUV). The phenol-formaldehyde treatment greatly reduced the discolouration of the coating compared to non-impregnated wood. Validerad;2022;Nivå 2;2022-04-13 (sofila);Funder: CT WOOD; OP RDE (CZ.02.1.01/0.0/0.0/16_019/0000803)

Furfurylated wood has been used widely for exterior purposes due to its superior dimensional stability and biological durability, though its fire resistance is not enhanced. Here, the introduction of the fire-retardant additive guanyl-urea phosphate (GUP) into furfurylated wood is reported. The treatment improved both the thermal and fire stabilities of the modified wood, as supported by the results of thermal gravimetric analysis (TGA) and limiting oxygen index (LOI) before and after accelerated ageing testing (according to EN 84) to determine the water resistance of the treatment. The results indicated that the hydroscopic GUP remained within the wood structure and provided superior thermal and fire properties. The work suggests the idea of combining GUP and furfuryl alcohol (FA), which has the prospective to impart substantial fire-retardancy to the furfurylated wood, thus increasing the potential for exterior applications. Validerad;2021;Nivå 2;2021-11-30 (johcin);Funder: OP RDE (CZ.02.1.01/0.0/0.0/16_019/0000803); CT WOOD – a centre of excellence at Luleå University of Technology supported by the Swedish wood industry

This study presents a novel application of the Wilhelmy plate method on welded joints of Scots pine sapwood and beech. Welding resulted in an increase in the contact angle (increased hydrophobicity) as well as a decrease in the water uptake and swelling of the welded pine-joint compared to non-welded pine. When the welding time was extended from 4 to 5 s, these properties were further pronounced. Welding of beech, on the other hand, led to an increase in the contact angle and a decrease in the water uptake, but an increase in the swelling. Fourier Transform Infrared spectroscopy showed that welding increased the aliphatic C–H and unsaturated C=C stretching absorption bands in pine and beech. Scanning electron microscopy showed a dense structure at the welded joints of the both species, giving evidence of a lower porosity that leads to a lower permeability as a result of the welding.

Guanyl-urea phosphate (GUP) was introduced into furfurylated wood in order to improve fire retardancy. Modified wood was produced via vacuum-pressure impregnation of the GUP-furfuryl alcohol (FA) aqueous solution, which was then polymerized at elevated temperature. The water leaching resistance of the treated wood was tested according to European standard EN 84, while the leached water was analyzed using ultra-performance liquid chromatography (UPLC) and inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). This new type of furfurylated wood was further characterized in the laboratory by evaluating its morphology and elemental composition using optical microscopy and electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDX). The chemical functionality was detected using infrared spectroscopy (FTIR), and the fire resistance was tested using cone calorimetry. The dimensional stability was evaluated in wet-dry soaking cycle tests, along with the mechanical properties, such as the Brinell hardness and bending strength. The fire retardancy of the modified furfurylated wood indicated that the flammability of wood can be depressed to some extent by introducing GUP. This was reflected in an observed reduction in heat release rate (HRR

Scots pine (Pinus sylvestris L.) wood impregnated with guanyl-urea phosphate/boric acid and a melamine-formaldehyde resin exhibited considerably increased resistance to leaching, while sustaining superior fire retardancy as tested by the limiting oxygen index (LOI) method. It was found that guanyl-urea phosphate has been well trapped in the wood structure by the cured resin network as evidenced by FTIR spectroscopy. Markedly, weight percentage gain (WPG) losses of fire retardant as low as 7.4% were achieved after excessive leaching of treated wood (EN 84). This was attributed to the effect of melamine-formaldehyde resin. Overall, this type of treatment could be a reliable method for producing fire-resistant pine wood for exterior uses.

Compressing the surface of sawn timber results in a substantial increase in hardness, and this opens up new market opportunities of using low-density timber species as the raw material for high-value wood products. Unfortunately, widespread commercialisation is hindered by the lack of an industrially viable surface densification process, the major obstacle being the set-recovery (SR) of the densified wood cells upon exposure to moisture. Our hypothesis is that partial dissolution of the crystalline cellulose during densification will largely prevent the SR of densified wood. We therefore evaluated the effect of ionic liquid (IL) or organic superbase pre-treatment on the elastic spring-back (SB), SR and Brinell hardness (HB) of surface-densified wood. Specimens of Scots pine were treated with solutions of ILs or superbases, and then densified in a hot press at temperatures between 200°C and 270°C. The SR was reduced from 90% for the control group to only about 10% for the treated materials. The treated and densified specimens exhibited a higher HB than their untreated and densified counterparts. The method presented in this study is a precursor to the development of a continuous densification process adapted for an open system. Further studies are needed to understand the underlying mechanisms of the pre-treatment.

A simple chemical solution-based synthesis route has been developed to prepare uniform and shape-controllable Ag3PO4 crystals. Tetrapod- and cube-shaped crystals having a size of about 9–10 μm were prepared from AgNO3 and NH4H2PO4 precursors, and pseudo-octahedral (equiaxial) crystals were prepared from AgNO3 and (NH4)2HPO4. TEM analysis revealed Ag3PO4 crystals to be electron beam sensitive materials, which under a voltage of 200 kV decompose to the metallic Ag, thereby demonstrating the difficulty in determining crystal facets and structural defects using conventional electron diffraction studies. UV–Vis diffuse reflectance spectroscopy was used to study the correlation between structural and optical properties of surfaces of Ag3PO4 crystals. Furthermore, a spatial 3-dimentional (3D) reconstruction of Ag3PO4 surface structures was performed from SEM images. The reconstruction produced realistic 3D mesh models, insomuch that the 3D reconstructed structures provided extra information about the examined crystals. Results suggested that the proposed synthesis route and performed spatial reconstruction of Ag3PO4 had the potential for simulating processing conditions to produce various microcrystals and explore material surface structures and reconstruction of microstructures.

The objective of this study was to explore an effect of the combined inorganic materials on the wood hardness and flame-retardancy properties in a concept of sustainable material management. Herein, the reinforcement of Scots pine (Pinus sylvestris L.) sapwood with sodium silicate and TiO2 nanoparticles via vacuum-pressure technique is reported. Pyrolysis of modified wood was studied by TG-FTIR analysis; the results showed that maximum weight loss for the modified wood was obtained at 40–50 °C lower temperatures compared to the reference untreated wood. The Gram–Schmidt profiles and spectra extracted at maxima absorption from Gram–Schmidt plots indicated chemical changes in wood–inorganic composites. SEM/EDS analysis revealed the presence of Na–O–Si solid gel within the wood-cell lumen and showed that TiO2 was homogeneously distributed within the amorphous Na–O–Si glass-forming phase to form a thin surface coating. EDS mapping further revealed the higher diffusivity of sodium into the cell wall compared to the silicon compound. The presence of amorphous sodium silicate and nano-TiO2 was additionally confirmed by XRD analysis. FTIR spectra confirmed the chemical changes in Scots pine sapwood induced by alkalization. Brinell hardness test showed that the hardness of the modified wood increased with the highest value (44% increase in hardness) obtained for 10% Na2SiO3–nTiO2 modified wood. The results showed good correlation between TG and flammability test; limiting oxygen index (LOI) values for the wood–inorganic composites increased by 9–14% compared to the untreated wood. Validerad;2019;Nivå 2;2019-09-18 (johcin);For correction, see: Garskaite, E., Karlsson, O., Stankeviciute, Z. et al. Correction: Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood composites. RSC Advances 9, 34086-34087 (2019). https://doi.org/10.1039/C9RA90075F

This work aimed at finding ways to improve the leaching resistance of Scots pine (Pinus sylvestris L.) wood impregnated with water soluble fire retardant (FR). Sapwood specimens of Scots pine (10 × 10 × 50 mm) were impregnated with aqueous solution of guanyl-urea phosphate (GUP)/boric acid (BA). Limiting oxygen index (LOI) revealed that treatment could improve the fire performance. At the same time, thermogravimetric analysis (TGA) illustrated increased thermal stability after the treatment. However, since the FR itself was not fixed within the wood cell wall, it was extracted during water leaching (EN 84), and the wood lost its fire retarding property. The resistance to leaching of FR from the treated wood can be primarily improved while maintaining high fire retarding performance and thermal stability of treated wood by mixing melamine-formaldehyde (MF) resin with GUP/BA before impregnation to the wood. To mix GUP/BA to MF solution, due to the acidic nature of GUP/BA, the condensation/polymerisation reaction would be accelerated in an undesired way even if the solution was adjusted to non-acidic by NaOH. The resulting solution would not penetrate deeply into the wood structure, whilst it would be difficult to re-use the FR solution. In order to avoid the reaction proceeding in an undesired way, introducing 0.5 wt% of pentaerythritol to the GUP/BA/MF solution can decrease the reaction rate. Additionally, it improved the weight percentage gain (WPG) and fire retarding performance, without significantly influencing the leaching resistance and thermal stability. Overall, it is suggested that such a treatment could be a suitable methodology for producing exterior-use fire-retardant pine wood. ISBN för värdpublikation: 978-3-030-41234-0, 978-3-030-41235-7

Research Highlights: In this study, the Generally Recognised as Safe (GRAS) compounds were applied in order to study mould-fungi growth on dried Scots pine sapwood. Background and Objectives: The transition to the use of more sustainable wood-material may be possible by applying GRAS compounds that can control and prevent contamination by primary colonising mould fungi. Materials and Methods: Kiln-dried sawn timber was treated with three different GRAS compounds, and different fungal inoculation methods applied in order to investigate differences in the development of fungal communities. Results: Substances based on potassium silicate significantly reduced fungal growth and mould contamination on the studied wood surfaces. By combining wood-surface treatments with GRAS compounds, fungal-area size as predictors and mould grade as response, a partial least squares (PLS) model that makes it possible to predict mould grade on wood surfaces was developed. The PLS model is a key component in the development of a smart grading-systems equipped by e.g. high-speed digital cameras for the early detection of fungal attack on wood surfaces in different applications. However, the measurements based on chemical characterisation should be the next step to take in order significantly to enhance the model and increase the range of robust applications. In the current study, a multivariate model describing the influence of each fungal-covering area on mould grade was presented for the first time. Validerad;2019;Nivå 2;2019-08-27 (johcin)

The objective of this study was to explore an effect of the combined inorganic materials on the wood hardness and flame-retardancy properties in a concept of sustainable material management. Herein, the reinforcement of Scots pine (

Changes in both formaldehyde legislations and voluntary requirements (e.g. Germany RAL) are currently the driving factors behind research on alternatives to amino-based adhesives; moreover, consumer interest in healthy and sustainable products is increasing in bio-based adhesives. Sources of formaldehyde emissions in wood-based panels as well as different emission test methods have been discussed, and the main focus of this review is on the research conducted on sustainable bio-based adhesive systems for wood panels. Lignin, tannin, protein, and starch have been evaluated as both raw materials and adhesive alternatives to existing amino-based thermosetting adhesives. Adhesion improving modifications of these bio-based raw materials as well as the available and experimental crosslinkers have also been taken into account.

Background The genus Pleurotus is most exploitable xylotrophic fungi, with valuable biotechnological, medical, and nutritional properties. The relevant features of the representatives of this genus to provide attractive low-cost industrial tools have been reported in numerous studies to resolve the pressure of ecological issues. Additionally, a number of Pleurotus species are highly adaptive, do not require any special conditions for growth, and possess specific resistance to contaminating diseases and pests. The unique properties of Pleurotus species widely used in many environmental technologies, such as organic solid waste recycling, chemical pollutant degradation, and bioethanol production. Methodology The literature study encompasses peer-reviewed journals identified by systematic searches of electronic databases such as Google Scholar, NCBI, Springer, ResearchGate, ScienceDirect, and ISI Web of Knowledge. The search scheme was divided into several steps, as described below. Results In this review, we describe studies examining the biotechnological feasibility of Pleurotus spp. to elucidate the importance of this genus for use in green technology. Here, we review areas of application of the genus Pleurotus as a prospective biotechnological tool. Conclusion The incomplete description of some fungal biochemical pathways emphasises the future research goals for this fungal culture.

The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS).

Correction for ‘Surface hardness and flammability of Na2SiO3 and nano-TiO2 reinforced wood composites’ by Edita Garskaite et al., RSC Adv., 2019, 9, 27973–27986.

During NiPtSi contact electrode processing and after the first thermal treatment to form Ni rich silicide, excessive Ni is removed by a strong acid mixture such as piranha (mixture of sulfuric acid and hydrogen peroxide. The post salicidation clean process has to be selective to all exposed materials: Si3N4, SiO2, NiPtSi, and NiPtSiGe (contact electrodes of source/drain for strain applications)). Performing a partition process with RTA1 (rapid thermal annealing) followed by Ni strip, followed by RTA2, and then with Pt strip is one method to check for NiPt removal. The Ni strip was performed using dilute nitric acid (20:1) and dilute aqua regia (1:5:4) and showed completed NiPt removal. A queue time study was also investigated after the Ni strip and after RTA2 for defect formation. Also, Pt removal using aqua regia solutions of various shelf-lives were tested. The result led to the conclusion that solutions of aqua regia with longer shelf-lives were also shown to be less effective in Pt residue removal. Using a High Productivity Combinatorial materials/process screening technique to reduce the number of product wafers used for evaluation process development, the etch rates of all the materials of interest were tested on blanket wafers. The chemistry consists of varying acid and base types and the relative combinations of these chemistries. Process conditions that consisted of various process chemistries, process temperatures, and degrees of fluid agitation (e.g. stirrer speed) were done on the same substrate.

This study assesses the potential of an open process for treatment of European Scots pine (Pinus sylvestris) with chemicals that could potentially make the surfaces stronger, more dimensionally stable, or more durable, depending on the treatment solution. The method provides an intermediate solution between full volume impregnation by pressure treatment and superficial surface treatment by dipping. Figuratively speaking, the process creates the equivalent of a layer of coating applied below the wood surfaces rather than above. Two different techniques were compared, namely, heating-and-cooling (H&C) and compression-and-expansion (C&E). Taking into account that commercial suppliers recommend 0.15 to 0.25 L/m2 of coating in sawn wood and 0.1 to 0.15 L/m2 in planed wood surfaces, then this study demonstrates that the H&C method can impregnate an equivalent amount of solution under the surfaces in less than 15 min using treatment temperatures below 150 °C.

Scots pine (Pinus sylvestris L.) sapwood lumber was collected after kiln drying and preservative treatment with Celcure AC 800 (a copper-amine wood preservative). Distribution of the preservative throughout the lumber was visually examined. Not all, but some samples showed specific localized areas without any preservative distribution throughout their entire length. Those samples were assessed further for anatomical properties, specifically in impregnated and unimpregnated areas. Additional study was conducted on the morphological nature and redistribution of lipophilic extractives using three different histochemical staining methods. Intrinsic wood properties – especially the frequency of axial resin canals and the percentage of canals blocked – were found to be responsible for the irregular distribution of the preservative. Furthermore, the inability to create continuous and frequent interstitial spaces due to the collapse of thin-walled ray cells throughout the lumber resulted in un-even distribution of preservatives. Staining techniques were useful to localize places with more or less abundance of extractives (e.g., fats) in impregnated and unimpregnated wood, which varied considerably. Histochemical observations revealed information pertaining to the kiln dry specific distribution and redistribution of extractives between the areas. Moreover, resin reallocation and modification in ray parenchyma and resin canals induced by kiln drying would be another reason for the impregnation anomalies.

Mold growth on dried Norway spruce and Scots pine sapwood boards was investigated in an accelerated outdoor field test for 96 days. The boards were dried using three different methods of stacking: single stacking, double stacking with the sapwood sides in each pair facing toward each other, and double stacking with sapwood sides facing outward. Drying was performed at three temperatures: 25°C, corresponding to air drying, and kiln drying at 70°C and 110°C. The degree of mold growth was visually assessed on both sides of each board. On average, pine boards showed a higher level of mold growth than the spruce boards. The highest average level of mold growth was found on the boards kiln dried at 70°C, whereas the air-dried boards and the boards kiln dried at 110°C showed considerably less mold growth. Stacking the boards during drying had a large impact on mold susceptibility of the sapwood. This study confirmed that, during the drying process, it is possible to direct the migration of nutrients in sapwood toward one chosen side of each board by double stacking; the opposite side leaches out, which has a great impact on surface mold growth. Chemical analyses of monosaccharide sugar gradients beneath the boards' surfaces confirmed the results.

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 s...

Wood modification with furfuryl alcohol is a non-toxic alternative to conventional preservation treatments. A process in which furfuryl alcohol polymerises in situ was previously proposed for chemical modification of wood. In the present work, liquid model systems were investigated using compounds that resemble repeating units of lignin to verify whether chemical bonds form between the furfuryl alcohol polymer and wood. Using different NMR spectroscopic techniques we confirmed that these model compounds do form covalent bonds with the polymerising polymer. The results indicate that the furan polymer grafts to lignin, supporting observations in similar studies performed with genuine wood materials.

In the present work, the formation of ester linkages in cellulosic materials during drying and heating was addressed. The results indicated that direct ester formation, without anhydride intermediate, occurs between carboxylic acids of suitable structure and cellulosic hydroxyls at 180°C, even after reaction times as short as 5 min. The 2(R)-hydroxybutyric acid is most effective in ester formation, followed by 2-ketobutyric acid and 3-hydroxybutyric acid. Hexanoic acid is less effective and veratric acid produces no esters at all. At lower temperatures, 2-ketobutyric acid is the most reactive compound. One conclusion is that a hydroxyl or keto group in α position of the carboxylic acids favours ester formation. Another finding is that three pyrrolidine structures are produced after esterification and aminolysis of 2-ketobutyric acid. One of the structures indicates that 2-ketobutyric acid is reactive in two positions and could therefore be a potential cross-linker. A critical parameter for ester formation is pH, and the results indicate that pH 5–6. All experiments were performed in a solid-state model system (on cellulosic filter paper) with low moisture content. Esterification of five carboxylic acids was studied. Samples were heated constantly at 180°C for 5 min or gradually from 22°C to 180°C over periods ranging from 5 to 45 min. Quantitative analysis of ester formation between the monocarboxylic acids and the hydroxyl groups of cellulose was performed by means of aminolysis and gas chromatography.

The synergistic effect of two fire retardants, a Si-Al compound and chlorinated paraffin, was tested on ultra-low density fiberboards (ULDFs). To further understand the mechanism of fire retardancy, morphologies of unburned and burned ULDFs were studied using a scanning electron microscope with energy dispersive spectroscopy. It was found that as the volume of the burned ULDFs shrank, some crevices appeared. In addition, less fly ash formed on the top of specimens, and more bottom ashes remained in the original framework, with a clear network of structure built by the fibers. Carbon was almost absent in the fly ash; however, the weight ratio of C in the bottom ashes reached the maximum (> 43%) of the composition. Oxygen, Al, and Si appeared to have varying weight ratios for different ashes. Oxygen content increased with increasing Si and Al contents. Furthermore, Cl sharply decreased to less than 1% after combustion. Therefore, upon combustion, it was found that almost all of the substances in ULDFs, except for the Si-Al compound, were pyrolyzed to volatile carbon oxides and Cl compounds, especially the fly ash and lightweight C compounds. Validerad; 2015; Nivå 2; 20150827 (aliwan)

Ultra-low-density fiberboards (ULDFs) were prepared by a liquid frothing technique using plant fibers as the matrix and Si-Al compounds as the filler to be used as a versatile bio-based composite. Si-Al compounds played an important role in the fire properties of ULDFs. Fire intensity and the amount of volatiles were significantly restrained because of the Si-Al compounds. To determine the combustion mechanism of ULDFs treated by Si-Al compounds, the microstructure of burned specimens was tested by chemical analysis, X-ray diffractometer (XRD), and infrared spectrometer (IR). According to the results from gas chromatography, glucose, xylose, and mannose disappeared in the bottom ashes. After combustion, the XRD profiles of the two ashes became weaker and broader; the sharpest peaks at 18.6o (2) that represented Si-Al compounds remained; the obvious peaks at 22o (2) from cellulose were gone. The results from IR suggested the characteristic functional groups OH, CH, and C=O from carbohydrate also disappeared, and absorbance at 1200 to 400 cm-1, which attributed to the vibration of Si-O, Al-O, and Si- O-Si bonds, increased. In conclusion, fibers are almost completely pyrolyzed at 780 °C. The crystalline structure of Si-Al compounds is rearranged and more amorphous silicon oxide and aluminum oxide are generated. Validerad; 2015; Nivå 2; 20150408 (aliwan)

Formation of benzyl esters from acetic and formic acids during heat treatment of birch at 160–200°C has been studied by gas chromatography. High concentrations of formic and acetic acids formed by the wood itself during hydrothermal treatment were found. The concentrations of acids increased with both treatment time and temperature. The maximum formic- and acetic acid concentrations found at 180°C and after 4 h of treatment performed in this work were 1.1 and 7.2%, based on dry-weight wood, respectively. The treated wood material was characterised by mechanical testing [bending tests perpendicular to the grain, modulus of rupture, modulus of elasticity, Brinell hardness, impact bending and colour measurements (CIE colour space)]. The experiments, where high concentration of acids was formed, showed severe losses in mass and mechanical strength. Indications of possible enhanced mechanical properties for the treated, compared with untreated birch wood were found around 180–200°C at short treatment times. This paper discusses possible degradation reactions coupled with the colour and mechanical properties in relation to acid formation, and suggestions for process optimisations.

A novel method for analysis of benzylic ether type lignin–carbohydrate bonds has been developed by using model compounds. Four diastereomers of model compound 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-3-(methyl β-d-glucopyranoside-6-O-yl)-1-propanol (GGMGP), were ozonized in acetic acid/water/methanol 16 : 3 : 1 for 1 h at 0°C. The product from ozonation of each diastereomer was saponified and the corresponding α-etherified tetronic acid (TAMGP) was isolated using ion exchange chromatography. Minor amounts of methyl β-d-glucopyranoside (MGP) and small amounts of a gluconic acid etherified with tetronic acid (TAGLCA), tetronic acid, gluconic acid, and glyceric acid were detected in the product mixture of ozonated benzylic ether type model compounds. The results suggest that a benzyl ether bond between lignin and carbohydrate is rather stable during the ozone treatment. Acid treatments with sulfuric acid or trifluoroacetic acid of the derived TAMGP led to cleavage of the glucosidic bond but only a small amount of products (tetronic acid and glucose) resulting from cleavage of the α-ether bond were formed. The successful chemical treatments were used for studies of benzylic ether bonds in Japanese red pine. The results suggest the presence of benzylic ether bonds to polysaccharides in the wood.

Chloroform was readily converted to formic acid through the nucleophilic attack of hydroxyl anion under the certain reaction conditions (pH>12, temp.>70°C). When guaiacol was reacted with hypochlorite at such reaction conditions, the generation of chloroform was almost completely reduced. Successful reduction of the chloroform generation was also observed in alkaline hypochlorite bleaching of kraft pulps and DIP without any loss in pulp quality.Even when the hypochlorite bleaching was carried out under the open system (no sealing of the reaction vessel). nearly 90% of the generated chloroform was converted to formic acid.

Methylβ-d-xylopyranoside was allowed to react withβ-O-4-type quinone methide without a catalyst to elucidate the reactivities of secondary hydroxyl groups at the C2, C3, and C4 positions. Benzyl ether-type lignin-carbohydrate complex (LCC) compounds linked at the C2 and C4 positions were predominant, at a ratio of 2∶3. However, the reactivity of the hydroxyl group at the C3 position was quite low. These results strongly suggest that the reactivity of the C2 hydroxyl group in xylan toward quinone methide intermediate is higher than that of the C3 hydroxyl group during biosynthesis of LCCs.

An ultra-low density fiberboard was made of plant fiber using a liquid frothing approach. The inflammability of the plant fiber limited its application as a candidate for building insulation materials and packaging buffering materials. Si-Al compounds were introduced into the foaming system because of the high temperature resistance of Si and Al compounds. The results from energy-dispersive spectroscopy suggested that the Si and Al relatively evenly covered the surface of the fibers, and their weight ratios in the material increased as a function of the amount of Si-Al compounds. The increasing weight ratios of Si and Al affected the fire properties of the material, reducing the released amount of heat, smoke, and off-gases such as CO and CO2, as well as decreasing the mass loss percentage, shown through the use of a Cone Calorimeter. It follows that Si-Al compounds have an evident collaborative effect on the halogen fire retardant. The system can effectively restrain the fire hazard intensity and the yields of solid and gas volatiles. Validerad; 2014; 20140804 (johsod)

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 Validerad; 2013; 20131003 (ysko)

We evaluate to what extent students are interacting with mobile devices in one of four ways intended in the design of a mobile learning activity. Video data from one class of fifth grade students were analyzed using a model of four different types of interaction. The evaluation shows that the students interacted with the devices in the ways intended in design 64% of the time. The contribution is an approach for translating learning goals to interaction design goals in mobile learning research. We conclude that this approach can be of value in designing and evaluating interaction with mobile devices for an entire mobile learning activity.

Acid reactions of hydrobenzoins : effect of catalyst and reaction medium on product composition

Evidence for the presence of lignin-carbohydrate bonds of the benzylic ether type in wood and pulps may be obtained by use of ozonation treatment to selectively degrade the lignin. It was found that the benzyl ether bond in 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxy-phenoxy)-3-(methyl-β-d-glucopyranosid-6-O-yl)-1-propanol was rather stable during ozonation in acetic acid-water-methanol 16∶3∶1 at 0°C. The corresponding acid, 3,4-dihydroxy-2-(methyl-β-d-glucopyranosid-6-O-yl)-butanoic acid, was found to be the major reaction product. The use of ozonation followed by acid hydrolysis in connection with studies of lignincarbohydrate linkages is briefly discussed.

The degradation of the erythro and threo isomers of the non-phenolic lignin model compound 2-(2,6-dimethoxyphenoxy)-1-(3,4-dimethoxyphenyl)-1,3-propanediol was examined. Enzymic and non-enzymic oxidation of the diastereomers was performed with Trametes versicolor lignin peroxidase and cerium(IV) ammonium nitrate, respectively. Mixtures of approximately equal amounts of the diastereomers were partially degraded and subsequently analyzed with TLC and 1H-NMR. Analysis of reaction mixtures from enzymic as well as non-enzymic oxidation, revealed a preferential degradation of the threo form. Preliminary analyses of enzymic reaction mixtures of either the erythro or threo isomer suggest they yield in part different products. The observations made would have implications for the understanding of how enzymes attack lignins. They should also be taken into consideration in experiments where model compounds are being used to mimic native lignin.

The key performance advantages and challenges of SOI CMOS for ULSI applications are discussed in detail. Included is an insightful analysis comparing the performance benefits of SOI technologies over its bulk-Si counterpart. The hysteretic trends of a floating-body PD/SOI inverter circuit are uniquely characterized using a Teradyne J971 system; and the charge-dump and self-heating effects are shown to be under control using an advanced 0.13 /spl mu/m SOI device technology. Future technology opportunities are described that could provide a viable roadmap of SOI technologies to leverage in the future.