Summary: Fiberboards were prepared using phenolic type resins (phenol‐formaldehyde) and sugarcane bagasse fibers. Lignin extracted through an organosolv process from sugarcane bagasse was used as substitute of phenol in phenolic resins from 40 (lignin‐phenol‐formaldehyde) to 100 wt.‐% (lignin‐formaldehyde) substitution. Some of the fibers were chemically modified by oxidation with chlorine dioxide and treatment with furfuryl alcohol (FA), leading to fibers coated with polyfurfuryl alcohol. Thermal analysis (DSC and TGA) of the prepolymers allowed setting up an efficient curing to prepare fiberboards. Impact strength and water absorption were measured showing the importance of the curing pressure to obtain good performance. When chemically modified fibers were used to prepare board samples, enhanced durability against white root fungi is observed, and to a less degree against brown root fungi. Sugarcane bagasse fiberboards were prepared from prepolymers where lignin substituted phenol up to 100%. This replaces these materials in advantageous position, relating to those prepared from phenol‐formaldehyde resins, due to their high content of renewable raw materials. The results obtained are promising for the utilization of sugarcane bagasse as raw materials for preparing fiberboards to be used in tropical areas.
Stabilization of sugarcane bagasse fiberboards made with unmodified and modified (ClO2 + furfuryl alcohol) fibers and phenolic resin after 8 weeks exposure against fungi. 相似文献
For the first time, curcuminoids known for their antioxidant and sunscreen properties were used for photoprotection of lignocellulosics. It was shown that complex between copper(II) and non-substituted curcumin 2, displaying remarkable photostability in ethyl acetate/ethanol solution, is able to photostabilize in some extend -carbonyl -O-4 lignin model and more efficiently spruce wood.
Der Versuch, Holz mit einem Kupfer(II) Komplex mit 1.7-Diphenyl-1.6-Heptadien-3.5-Dion, einem nicht phenolischen Curcumin, zu schützen
Zusammenfassung Zum ersten Mal wurde Curcumin, das für seine antioxidante und sonnenschützende Wirkung bekannt ist, für den Lichtschutz von Lignin-Cellulosen eingesetzt. Es wurde gezeigt, dass der Kupfer(II)-Komplex mit einem unsubstituierten Curcumin 2, das in einer Lösung aus Ethylacetat/Ethanol über eine bemerkenswerte Photostabilität verfügt, die Fähigkeit besitzt, -Carbonyl -O-4 Lignin-Moleküle und noch effizienter Fichtenholz gegen Lichtabbau zu stabilisieren.
The duration of the movement aftereffect was measured in twenty-four normally binocular subjects and in eighteen subjects who lacked steropsis as a consequence of childhood strabismus. Aftereffects were generated monocularly and binocularly, and compared to those which occurred after adaption of one eye and testing with the other. Normal subjects were categorized on two indices of eye dominance, which involved sighting and rivalry tests. The monocular-aftereffect durations were slightly longer when the dominant eye was use, and interocular transfer from the dominant eye to the nondominant eye was greater than the transfer in the reverse direction; however, these differences were not statistically significant. The results from the strabismic subjects suggested that they fell into two distinct groups: one group (seven of the eighteen subjects) experienced no interocular transfer in either direction; the group did yield some interocular transfer, and it was generally greater after adaptation of the dominant eye and testing the nondominant eye than in the reverse direction. Six of the seven subjects who failed to show any transfer still had misalignment of the visual axes, but this was not the case in any of the subjects exhibiting transfer. 相似文献
ABSTRACT: The inhibitory activity of chitosan-based edible coatings and films was assessed against the Aspergillus niger food pathogen and deterioration microorganism. Spore-counting assays showed an almost total inhibition of A. niger growth when either film-forming solution or film were used at a low concentration of chitosan (0.1% w/v). Epifluorescence microscopic results showed the action of chitosan on the relative proportion of RNA compared with DNA. The water vapor permeability (WVP) of chitosan film was relatively low compared with the poor moisture barrier of some polysaccharide films. Moreover, a coating with chitosan film on an agar gel, used as a food model, induced a 30% reduction in water loss. These results showed potential applications of chitosan-based films as bioactive packaging with properties to limit the food dehydration phenomenon. 相似文献
Enzymatic synthesis of fatty acid glucose esters from different fatty acyl donors are performed via enzymatic catalysis in the presence of Candida antarctica lipase B (CALB), using acetonitrile as the solvent. The acyl donor nature (fatty acid or fatty acid vinyl ester) and structure are varied. Lower reaction rates and lower conversions are obtained with fatty acids in comparison to their corresponding vinyl esters. Moreover, the acyl donor with the longest chain length gives the highest conversions. The presence of unsaturation on the acyl donor chain is also shown to be detrimental to the conversion. Practical Applications: The practical applications of the present work are related to the production of gluco‐esters that could be used as nonionic surfactants as detergents, cosmetics and food emulsifiers, emollients or conservatives, respectively. In this study, it is shown that in order to get high production yields, each reaction parameter has to be tuned properly. 相似文献
Early or primary injury due to brain aggression, such as mechanical trauma, hemorrhage or is-chemia, triggers the release of damage-associated molecular patterns (DAMPs) in the extracellular space. Some DAMPs, such as S100B, participate in the regulation of cell growth and survival but may also trigger cellular damage as their concentration increases in the extracellular space. When DAMPs bind to pattern-recognition receptors, such as the receptor of advanced glycation end-products (RAGE), they lead to non-infectious inflammation that will contribute to necrotic cell clearance but may also worsen brain injury. In this narrative review, we describe the role and ki-netics of DAMPs and RAGE at the acute phase of brain injury. We searched the MEDLINE database for “DAMPs” or “RAGE” or “S100B” and “traumatic brain injury” or “subarachnoid hemorrhage” or “stroke”. We selected original articles reporting data on acute brain injury pathophysiology, from which we describe DAMPs release and clearance upon acute brain injury, and the implication of RAGE in the development of brain injury. We will also discuss the clinical strategies that emerge from this overview in terms of biomarkers and therapeutic perspectives 相似文献
European Journal of Wood and Wood Products - The relation between lignin-related structure and antifungal activities was assessed against the white-rot fungus Trametes versicolor and two brown-rot... 相似文献