Effects of tree species and wood particle size on the properties of cement-bonded particleboard manufacturing from tree prunings.

This study investigated the possibility of using the prunings of six locally grown tree species in Saudi Arabia for cement-bonded particleboard (CBP) production. Panels were made using four different wood particle sizes and a constant wood/cement ratio (1/3 by weight) and target density (1200 kg/m3). The mechanical properties and dimensional stability of the produced panels were determined. The interfacial area and distribution of the wood particles in cement matrix were also investigated by scanning electron microscopy. The results revealed that the panels produced from these pruning materials at a target density of 1200 kg m(-3) meet the strength and dimensional stability requirements of the commercial CBP panels. The mean moduli of rupture and elasticity (MOR and MOE) ranged from 9.68 to 11.78 N mm2 and from 3952 to 5667 N mm2, respectively. The mean percent water absorption for twenty four hours (WA24) ranged from 12.93% to 23.39%. Thickness swelling values ranged from 0.62% to 1.53%. For CBP panels with high mechanical properties and good dimensional stability, mixed-size or coarse particles should be used. Using the tree prunings for CBPs production may help to solve the problem of getting rid of these residues by reducing their negative effects on environment, which are caused by poor disposal of such materials through direct combustion process and appearance of black cloud and then the impact on human health or the random accumulation and its indirect effects on the environment.

Effect of salinity on moisture content, pigment system, and lipid composition in Ephedra alata Decne.

The present work was carried out to uncover the effect of salinity stress on shoot moisture percentage, pigment content and lipid composition of Ephedra alata Decne. The results suggested that salinity caused significant decrease in plant moisture content. The chl. a, b and carotenoids showed significant decrease with increasing concentration of salt. Total pigment content also showed decline at all salt stress levels. Salt stress caused significant decrease in total lipids (TL), triacylglycerol (TG) and sterol (S) accompanied with an increase in diacylglycerol (DG), sterol ester (SE), and non-esterified fatty acids (FAA) of E. alata. Moreover, saline stress caused significant decrease in all phospholipid fractions except phosphatidic acid which increases during salt stress. Salinity stress resulted in increase of saturated fatty acids and decreases the percentage of un-saturated fatty acids in E. alalta.