Propiedades físicas y mecánicas de paneles a base de partículas de corteza externa de abeto blanco: Mezcla de paneles con partículas de madera versus fibra de madera

El uso de la corteza externa de abeto blanco en la fabricación de canoas por las primeras naciones de Canadá es un ejemplo de su uso más antiguo. Esto confirma sus características hidrófugas, la cual puede ser explotada mediante su uso en la superficie del panel compuesto de 3 capas para protegerlo de filtraciones de humedad. Estos tableros fueron fabricados con partículas de corteza externa en las capas superficiales, y con partículas gruesas o fibras de madera en el corazón. Un experimento factorial en un diseño de bloque completo hizo posible realizar el diseño de experimento. Los dos grandes factores considerados, fueron el porcentaje de corteza en las capas superficiales con 3 niveles y el tipo de material usado en el corazón, con dos niveles respectivamente (partículas y fibras de madera). Cuatro réplicas fueron hechas para cada panel. Sólo los tableros con partículas gruesas de madera en el corazón pasaron todas las pruebas físicas satisfaciendo los requerimientos del interior de los tableros de partículas. Paneles con 45% de partículas de corteza en la superficie y 55% de partículas de madera en el corazón fueron seleccionados como los mejores, debido a su buena estabilidad dimensional. AbstractThe use of outer white birch bark in canoes is an example of its oldest use by the first nations in Canada. This use confirms the hydrophobic characteristics of this bark, which can be capitalized on by using it in the outer layers of three-layer mixed composite panels in order to protect them from water infiltration from their surface. These panels were made up of outer white birch bark particles in the surface layers with coarse wood particles or wood fibres in the core layer. A factorial experiment used in a complete block design permitted to carry a suitable statistical analysis of measured properties. The two main considered factors were respectively the bark percentages in the surface layers with three levels and the type of material used in the core with two levels. Four replicates were done for each panel. The panels with wood particles in the core layer gave physical and mechanical properties satisfying the indoor requirements for particleboards and those with wood fibres in the core layer passed the requirement of medium fibres density board. Panel with 45% bark particles in the surface and 55% wood particles in the core was selected as the best because of its good dimensional stability

Steroidal glycosides from the flowers of Allium leucanthum

Furostanol and spirostanol glycosides 1 and 2 were isolated from the flowers of Allium leucanthum, a Caucasian endemic species that grows in Georgia. The structures were established on the base of chemical evidence and spectral analyses ( (1) H, (13) C NMR, (1) H- (1) H COSY, (1) H- (13) C COSY, HMBC, and HR-MS) data. Compound 1 (leucofuranoside A) was reported for the first time and was identified as 26-O-beta-Dglucopyranosyl-(25R)-5 alpha-furostane-3 beta,6 beta-diol-3-O-beta-D-glucopyranosyl-(1 -> 2)-O-beta-D-xylopyranosyl-(1 -> 3)-O-beta-D-glucopyranosyl-(1 -> 4)-beta-D-alactopyranoside. Compound 2 was identified as (25R)-5 alpha-spirostane-3 beta,6 beta-diol-3-O-beta-D-glucopyranosyl-(1 -> 2)-beta-D-glucopyranosyl-(1 -> 4)-beta-D-galactopyranoside and described for the first time in the genus Allium

Volatile compounds in the foliage of balsam fir analyzed by static headspace gas chromatography (HS-GC) : an example of the spruce budworm defoliation effect in the boreal forest of Quebec, Canada

Many studies have focused on the influence of needle defense compounds that are produced when trees are attacked. Spruce budworm is the most important defoliator of conifers in eastern North America causing tree mortality. Volatile components such as terpenes are of importance as they are known to be agents of defense in plants and trees against many aggressors like spruce budworm. In this study, the static headspace gas chromatography (HS-GC) method was used to evaluate volatile compounds in the foliage of balsam fir (Abies balsamea) in order to compare the results obtained with the traditional GC–MS method. An advantage of analyzing plant volatile compounds with the HS-GC was the simplicity of execution, allowing a large number of samples to be treated. The most abundant volatile molecules were identified on the HS-GC chromatogram, except for some compounds such as α-thujene, fenchone, terpin-1-en-4-ol and α-terpineol. In addition to the qualitative analysis of terpene, a quantitative analysis of β-phellandrene was done to compare the variation of this compound between a control and a defoliated site. This study suggests that β-phellandrene was released as a response to injuries when the site was heavily defoliated by spruce budworm

Enhancing exterior durability of jack pine by photo-stabilization of acrylic polyurethane coating using bark extract. Part 1: Effect of UV on color change and ATR–FT-IR analysis

Heat-treated wood is a value-added product but its exposure to various environmental factors leads to discoloration of wood surface due to the photochemical reactions. Discoloration has become an important economic problem for wood industries since product specifications are now more demanding. In addition, stricter environmental legislations necessitate the development of environmentally friendly transparent coatings with minimal use of chemicals which balances aesthetic and protection. In this study, the acrylic polyurethane coating was improved with the addition of natural antioxidant (bark extract) and lignin stabilizer alone or in combination to enhance the resistance of this coating to different weathering factors. An accelerated aging test was conducted with the aim of comparing the acrylic polyurethane coatings containing different additives with the commercially available pigmented solvent borne coating used by industry and organic UV absorbers. The modifications in chemical structure of coatings were characterized by ATR–FT-IR analysis. The color change data showed that the coating containing bark extract was the most effective and performed better than the industrial coating. However, the visual assessment showed that the coating containing bark extract and lignin stabilizer had the best performance. FT-IR analyses suggested that the chain scission reaction took place throughout the weathering but its effect was not significant for any of the coatings

Surface degradation of CeO2 stabilized acrylic polyurethane coated thermally treated jack pine during accelerated weathering

The thermally treated wood is a new value-added product and is very important for the diversification of forestry products. It drew the attention of consumers due to its attractive dark brown color. However, it loses its color when exposed to outside environment. Therefore, development of a protective coating for this value added product is necessary. In the present study, the efficiency of CeO2 nano particles alone or in combination with lignin stabilizer and/or bark extracts in acrylic polyurethane polymer was investigated by performing an accelerated weathering test. The color measurement results after accelerated weathering demonstrated that the coating containing CeO2 nano particles was the most effective whereas visual assessment suggested the coating containing CeO2 nano particles and lignin stabilizer as the most effective coating. The surface polarity changed for all the coatings during weathering and increase in contact angle after weathering suggested cross linking and reorientation of the polymer chain during weathering. The surface chemistry altered during weathering was evaluated by ATR-FTIR analysis. It suggested formation of different carbonyl byproducts during weathering. The chain scission reactions of the urethane linkages were not found to be significant during weathering

Isolation and Identification of Steroid and Flavonoid Glycosides from the Flowers of Allium gramineum

peer reviewedThe isolation and identification of β-sitosterol 3-O-β-glucopyranoside, quercetin 3-O-β-glucopyranoside, isorhamnetin 3,4'-di-O-β-glucopyranosideand isorhamnetin 3,7-di-O-β-glucopyranosidefrom the flowers of Allium gramineumthat growsin Georgia.The structures of isolated compounds havebeen determined by 1H and 13C nuclear magnetic resonance (NMR) Isolation and Identification of Steroid and Flavonoid Glycosides from the Flowers of Allium gramineum. Available from: https://www.researchgate.net/publication/305851744_Isolation_and_Identification_of_Steroid_and_Flavonoid_Glycosides_from_the_Flowers_of_Allium_gramineum [accessed Aug 5, 2016]

Bidesmosidic betulin saponin bearing L-rhamnopyranoside moieties induces apoptosis and inhibition of lung cancer cells growth in vitro and in vivo

Betulin has a wide range of biological and pharmacological properties with its anticancer activity attracting most of the attention as it offers a possible alternative treatment to chemotherapy. However, betulin’s in vivo biological effectiveness is limited by its poor solubility. As such, we synthesized polar glycosylated derivatives to increase its hydrosolubility and enhance its pharmacological properties. Among these synthesized compounds, 28-O-α-l-rhamnopyranosylbetulin 3β-O-α-l-rhamnopyranoside (Bi-L-RhamBet) was assessed for its cytotoxic effects against a suite of lung cancer cell lines. We also investigated its mechanism of action using an A549 lung cancer cell line. Our results showed that Bi-L-RhamBet exhibited potent cytotoxic activity toward lung cancer cell lines including A549, NCI-H2087, NCI-H522, NCI-H1993 NCI-H1755, and LLC1 having IC50 values ranging from 2.9 to 5.9 μM. Moreover, Bi-L-RhamBet (50 mg/kg) significantly inhibited tumor growth with a treatment-to-control ratio (T/C) of 0.54 and a tumor growth inhibition rate of 46% at day 18 (p < 0.05). Microscopic observations of A549 cells, double stained with acridine orange and ethidium bromide, showed apoptotic features. Bi-L-RhamBet induced activation of pro-apoptotic caspases 8, 9, and 3/7 as well as causing DNA fragmentation. Moreover, a marked increase in mitochondrial ROS (mROS) was coupled with a reduction of mitochondrial potential. Interestingly, the presence of mitochondrial electron transport chain (ETC) inhibitors, including rotenone, malonate, and antimycin A, reduced mROS production, and the activation of caspases suggesting that Bi-L-RhamBet disturbs the ETC. Finally, dichloroacetate, a pyruvate dehydrogenase kinase inhibitor potentiated the cytotoxicity of Bi-L-RhamBet against A549 cells. Taken together, these data suggest that Bi-L-RhamBet can induce apoptotic cell death via disturbance of mitochondrial electron transfer chain, reduced ROS production, and decreased membrane potential

New antibacterial dihydrochalcone derivatives from buds of Populus balsamifera

Three new dihydrochalcone derivatives, balsacones A, B, and C, along with seven known compounds, were isolated from the buds of Populus balsamifera. The structures of the new compounds were elucidated by the analysis of spectroscopic data. Only balsacone A, B, and C were significantly active against Staphylococcus aureus with MIC values ranging from 3.1 to 6.3 μM

Coumarins from Daphne axilliflora (Keissl.) Pobed. and the anatomical characteristics of its leaves and stems

The aim of the study was to determine the stable diagnostic traits of a Caucasian endemic plant Daphne axilliflora (Keissl.) Pobed. and study its phytochemical composition. The following stable diagnostic characteristic were identified during the microstructural analysis: leaf surface glabrous, hypostomatic, dorsoventral; epidermal cells chaotic; curved with curved walls on both the upper and lower epidermis; stomata anomocytic; well visible chloroplasts, rhomboid and needle shaped crystals in lower leaf epidermis; leaf vascular bundles reverse-collateral; vascular system monocyclic, bilateral; wood diffuse-porous; xylem parenchyma is apotracheal, scanty metatracheal; vessel walls are predominantly characterized by spiral and pitted thickening; collenchyma lamellar; radial rays in single rows, heterogeneous. Phytochemical analysis showed the presence of terpene and phenolic substances, including coumarins. Two well-known coumarins (daphnin and daphnetin) were isolated and identified

Iso-caryophyllene cytotoxicity induced by lipid peroxidation and membrane permeabilization in L-929 cells

Iso-caryophyllene, a sesquiterpene, is present in several essential oils from vegetable species. In previous work, iso-caryophyllene was found cytotoxic against in vitro culture cell lines but its mechanism of action is still unknown. Reactive oxygen species (ROS) and lipid oxidation induced by iso-caryophyllene were assessed using DCFH-DA and BODIPY-C11, respectively. The results show that iso-caryophyllene induces significant overproduction of ROS by about 187 % at 100 µM and lipid oxidation, which are both partially inhibited by a-tocopherol. The effect of isocaryophyllene on membrane permeabilization was evaluated using calcein-AM assay that show that iso-caryophyllene causes membrane permeabilization and cell shrinking. a-Tocopherol significantly prevents membrane permeabilization, cell shrinking and cell death, suggesting that lipid oxidation is in part implied in the cytotoxicity. Electrochemical experiments indicate that the superoxide anion reacts with iso-caryophyllene and possibly form oxidized derivatives which could initiate lipid oxidation. Interestingly, superoxide anion reacts more readily with a-tocopherol in comparison with iso-caryophyllene which could explain its protective effect on cellular membrane