Assessment of certain wood quality parameters of selected genotypes of Melia dubia Cav. grown in a seedling seed orchard
Certain wood quality parameters of about 9-year-old Melia dubia Cav. trees grown in a seedling seed orchard at Yeshwanthpura Research Station of Kolar research range, Karnataka India were studied. Trees were categorized into three classes depending upon their girth at the breast height––small (<40 cm), medium (40–60 cm) and big (>60 cm). Different anatomical (gross structure), physical and mechanical properties of the wood were evaluated using standard testing procedures and Indian Standards. The results of this study showed that there was no significant difference in the heartwood percentage and specific gravity among three girth classes. High shrinkage values from green to oven-dry condition in all the classes indicate that the timber is dimensionally unstable compared to teak. The static bending strength parameters––FS at LP, MOR and MOE, compression strength parallel to grain, compressive strength perpendicular to grain at limit of proportionality and surface hardness (side and end) were evaluated and compared among all the three girth classes. The data on mechanical properties were statistically analysed using ANOVA between three girth classes. The results on wood quality parameters may be utilized in selection of suitable genotypes for raising large scale plantations.
Treatability of Melia composita using vacuum pressure impregnation
The performance of treated wood in the field is ultimately affected by retention and penetration of preservative in wood. In the present study, a new preservative system ZiBOC and a commercially used preservative copper-chrome-arsenate (CCA) were used for evaluation of treatability of Melia composita by the vacuum pressure method at different pressure levels in unsealed and end sealed specimens. The retention and penetration levels of both the preservatives were significantly different at (P< 0.05) in sapwood, heartwood and pith zones. Melia composita exhibited treatability class ‘C’ (21 – 42% penetration). The results revealed that longitudinal penetration in Melia composita was the dominant flow as examined by spot test for copper in unsealed and end sealed specimens.
The peculiar thermo-structural behavior of the anionic lipid DMPG.
Aqueous dispersions of the anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG), around 100 mM ionic strength, are known to exhibit a thermal behavior similar to that of the largely studied lipid dimyristoyl phosphatidylcholine (DMPC), which undergoes a gel to liquid crystalline phase transition at 23 degrees C, well characterized by differential scanning calorimetry (DSC), and other methods. However, at low ionic strength, DMPG has been shown to present a large gel-fluid transition region, ranging from 18 to 35 degrees C. This intermediate phase is optically transparent and characterized by a continuous change in membrane packing. Structural properties of the DMPG gel-fluid transition region will be discussed, based on results obtained by several techniques: electron spin resonance (ESR) of spin labels at the membrane surface and intercalated at different depths in the bilayer; light scattering; DSC; small angle X-ray scattering (SAXS); and fluorescence spectroscopy of probes in the bilayer.