ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (6,427)
Collection
  • Articles  (6,427)
Source
Publisher
Years
Journal
Topic
  • 1
    facet.materialart.
    Unknown
    Mineralization treatment of European oak heartwood with calcium oxalate for improved fire retardancy (2021)
    De Gruyter
    Details
    Publication Date: 2021-08-11
    Description: Within the focus to apply substances for wood protections, here fire retardants, with low hazardous and low environmental impact is of interest. Additionally, European oak is an attractive species for various interior and exterior applications. However, oak is classified as very heavily treatable and thus impregnation is challenging. However, the focus of this study was to treat European oak with a new fire retardant based on an in-situ calcium oxalate deposition. Thin oak specimens with a thickness of 4 mm were investigated with two various formulations of aqueous salt solutions (potassium oxalate and calcium chloride, and potassium oxalate and calcium acetate) to obtain an in-situ mineralization of calcium oxalate during a two-step impregnation process. The uptake, the distribution, and the penetration of the salts for both applied formulations were investigated. Additionally, fire retardant properties were investigated in a single flame source test. It could be demonstrated that an acceptable degree of treatability was achieved for both applied formulations. The fire retardancy of the so mineralized material was clearly improved. Synergetic effects which might be caused by the reaction side products of the various formulations were found to be neglectable.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    Sound absorption characteristics of three species (binuang, balsa and paulownia) of low density hardwood (2021)
    De Gruyter
    Details
    Publication Date: 2021-08-05
    Description: In this study, the sound absorption coefficient of three low density hardwoods – binuang, balsa and paulownia – were investigated. Their gas permeability and pore size were measured, and their pore shapes were classified into through pore, blind pored, and closed pore, as specified by the International Union of Pure and Applied Chemistry (IUPAC). Among the three species, obvious that paulownia had lowest sound absorption when the two of others showed higher sound absorption. Although paulownia is a high porosity wood, most of its vessels are blocked by tyloses; it is therefore difficult for sound waves to enter its pores, which results in poor sound absorption performance. This study showed that the higher the through pore porosity, the higher was the gas permeability, which led to improvement of the sound absorption performance. It was also found that the sound absorption coefficient of the three species woods increased at low frequencies as the size of an air cavity between the specimens and tube’s wall increased.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Ultrasound to estimate the physical-mechanical properties of tropical wood species grown in an agroforestry system (2021)
    De Gruyter
    Details
    Publication Date: 2021-06-24
    Description: The great diversity of tropical wood species makes it difficult to obtain information about their technological properties. The present work employed ultrasound to estimate the physical and mechanical properties of four wood species: African mahogany (Khaya senegalensis), ‘freijó’ (Cordia goeldiana), ‘paricá’ (Schizolobium amazonicum), and teak (Tectona grandis). Nineteen-year-old adult trees were selected and harvested from an agroforestry system (AFS) located in the Brazilian Amazon. From the harvested trees, 1.5 m logs were sawn and test specimens were obtained for physical-mechanical assays. The ultrasound propagation speed (V 0) and the dynamic modulus of elasticity (E d ) were obtained from applying ultrasound longitudinally in wood samples. Values of V 0 decreased from the lightest wood (paricá) to the heaviest (African mahogany), and E d presented the opposite behavior. For the physical properties, the coefficient of determination (R 2) ranged from 12 to 35% and the best linear regression models were fitted for the basic density, having V 0 and E d as independent variables. For the mechanical properties, the values of R 2 varied from 18 to 63% and higher correlations were found between parallel-to-grain compression strength and E d , and rigidity, static bending and Ed. Ultrasound presented the potential to estimate the properties of tropical wood species from the ASF.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Improved chemical pulping and saccharification of a natural mulberry mutant deficient in cinnamyl alcohol dehydrogenase (2021)
    De Gruyter
    Details
    Publication Date: 2021-05-14
    Description: Lignin content and its molecular structure influence various wood characteristics. In this study, the anatomical and physicochemical properties of wood derived from a naturally occurring mulberry mutant deficient in cinnamyl alcohol dehydrogenase (CAD), a key enzyme in lignin biosynthesis, were analyzed using conventional staining assays on stem sections, length and width measurements of xylem fiber cells, wood pulping and saccharification assays, and sugar compositional analysis of extractive-free wood powder. The present data indicate that the mutation in the CAD gene leads to improved wood delignification efficiency, increased pulp yield under alkaline pulping conditions, and enhanced saccharification efficiency following alkaline pretreatment. This study opens up new avenues for the multipurpose use of the mulberry CAD-deficient mutant as a raw material for biorefinery processes, in addition to its traditional use as a favored feed for silkworms.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Indoor storage time affects the quality and quantity of volatile monoterpenes emitted from softwood timber (2021)
    De Gruyter
    Details
    Publication Date: 2021-04-30
    Description: Wood as a construction material affects indoor environmental quality by moisture buffering, good acoustic properties and by the wood specific volatile organic compounds (VOC). The most abundant VOCs of soft wood are volatile monoterpenes (VM) giving the typical odor of wood. In the present study, long-term VM emissions of wood of two northern coniferous tree species, Scots pine and Norway spruce were observed regularly during one year in storage. Fresh and dried 20 cm long wood blocks were placed in a test chamber; VMs were collected with the solid phase micro extraction fiber and analyzed by gas chromatography-mass spectrometer. Average emission of nine different VMs, α- and β-pinene, 3-carene, limonene, terpinolene, myrcene, camphene, ortho-cymene and ƴ-terpinene, decreased 68–87% during one-year long storage. Moisture content (MC), knots, tree species and tree individual affected the VM emissions from wood. When a certain level of MC (12%) was reached, the VM levels decreased, but the method of drying (industrial or dried in storage) did not affect the amount of released VMs. Rehydration and dehydration increased and decreased VM emissions, respectively. Moreover, two of the eight Scots pine heartwood planks contained almost no 3-carene while being the most abundant monoterpene in the others.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Frontmatter (2021)
    De Gruyter
    Details
    Publication Date: 2021-04-29
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Dynamic strength properties and structural integrity of wood modified with cyclic N-methylol and N-methyl compounds (2021)
    De Gruyter
    Details
    Publication Date: 2021-04-28
    Description: Cyclic N-methylol compounds have been used for cell wall impregnation modifications of wood. Besides an improved decay resistance and dimensional stability, the modifications resulted in a decrease of wood’s dynamic strength properties. However, the mechanisms behind a significant loss in dynamic strength are not fully understood yet. In this study, wood blocks were treated with the N-methylol compounds 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and methylated DMDHEU (mDMDHEU) and the N-methyl compound 1,3-dimethyl-4,5-dihydroxy-ethyleneurea (DMeDHEU). In order to study the factors that control the changes of wood performance under dynamic loads, single (impact bending strength, IBS) and multiple dynamic impact (resistance to impact milling, RIM) tests were applied. It became evident, that reductions in IBS and RIM increased with increasing solid content, formaldehyde content and catalyst concentration of the impregnation solutions, but were not affected by a cold-water leaching. Differences in structural integrity of wood modified with N-methylol and N-methyl compounds were more pronounced than those of IBS. Therefore, RIM appeared more sensitive to changes on cellular level, as a higher degree of co-condensation of the N-methylol compounds with cell wall polymers was expected in comparison with the N-methyl compound.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    The impact of acid hydrolysis conditions on carbohydrate determination in lignocellulosic materials: a case study with Eucalyptus globulus bark (2021)
    De Gruyter
    Details
    Publication Date: 2021-04-20
    Description: Lignocellulosic biomass represents a suitable feedstock for production of biofuels and bioproducts. Its chemical composition depends on many aspects (e.g. plant source, pre-processing) and it has impact on productivity of industrial bioprocesses. Numerous methodologies can be applied for biomass characterisation, with acid hydrolysis being a particularly relevant step. This study intended to assess the most suitable procedures for acid hydrolysis, taking Eucalyptus globulus bark as a case study. For that purpose, variation of temperature (90–120 °C) was evaluated over time (0–5 h), through monosaccharides and oligosaccharides contents and degradation. For glucose, the optimal conditions were 100 °C for 2.5 h, reaching a content of 48.6 wt.%. For xylose, the highest content (15.2 wt.%) was achieved at 90 °C for 2 h, or 120 °C for 0.5 h. Maximum concentrations of mannose and galactose (1.0 and 1.7 wt.%, respectively) were achieved at 90 and 100 °C (2–3.5 h) or at 120 °C (0.5–1 h). These results revealed that different hydrolysis conditions should be applied for different sugars. Using this approach, total sugar quantification in eucalyptus bark was increased by 4.3%, which would represent a 5% increase in the ethanol volume produced, considering a hypothetical bioethanol production yield. This reflects the importance of feedstock characterization on determination of economic viability of industrial processes.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Superhydrophobic wood surface fabricated by Cu2O nano-particles and stearic acid: its acid/alkali and wear resistance (2021)
    De Gruyter
    Details
    Publication Date: 2021-04-20
    Description: Reducing the hydrophilic nature of wood could enhance dimensional stability and improve life cycle performance. Masson pine and pecan wood were modified to create superhydrophobic, self-cleaning functions by spray-coating with Cu2O nano-particles (Cu2O NPs)/phenol formaldehyde (PF) resin mixed solution followed by immersion in a stearic acid ethanol solution. Two types of Cu2O NPs, derived from different concentrations of copper chloride (CuCl2) were evaluated for their ability to improve hydrophobicity of wood surface. A special petal-shaped structure on the edge of Cu2O NPs was found on modified pecan wood, and water contact angles (WCA) of both kind of modified wood reached around 155° and sliding angles (SA) less than 10°. Meanwhile, low liquid permeability and excellent repellency to aqueous solutions with pH = 1 to 13 were achieved. The critical WCA around 150° was also maintained on modified wood surfaces after being immersed in strong acid (pH = 2) and strong alkali (pH = 12) solutions for 12 h. Furthermore, remarkable mechanical durability was obtained after harsh abrading test, which could be attributed to the high bond strength from cured PF resin adhesive. Such highly waterproof, acid/alkali resistant and hard-wearing superhydrophobic surface must have potential to be widely applied in wood products industry.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Cellular-level chemical changes in Japanese beech (Fagus crenata Blume) during artificial weathering (2021)
    De Gruyter
    Details
    Publication Date: 2021-04-20
    Description: Since wood chemical components can be depolymerized and modified by weathering, a better understanding of the mechanisms governing these processes in needed to develop effective protection methods for wood surfaces. Unfortunately, very little has been reported about the micro-scale chemical changes in wood, particularly hardwood, during weathering. The purpose of the present work is to determine the degradation behavior of Japanese beech (Fagus crenata Blume) under artificial weathering at the cellular-level. Herein, the structural and micro-distributional changes in wood components during weathering were investigated using micro-Raman spectral and chemical mapping analyses. The Raman spectra showed that weathering facilitated lignin degradation and modification. The degradation behavior of lignin differed depending on the type of wood tissue. The rate of lignin reduction followed a descending order: vessel element 〉 axial parenchyma cell 〉 wood fiber. Raman mapping determined that cellular-level lignin reduction on the surface layers differed for wood species. Although lignin degradation of cedar tracheids proceeded from both the surface and the cell lumen, the lignin in beech fibers degraded according to the depth.
    Print ISSN: 0018-3830
    Electronic ISSN: 1437-434X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by De Gruyter
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...