Seeds of two selected clones of Artemisia annua L., TC1 and TC2, were germinated in a greenhouse. Four-week-old seedlings from both clones were grown in the Thù Ðúc province of Ho Chi Minh City on 2nd January 2009 and Ðà Lat on 20 th January 2009. During this study period in Thù Ðúc province, which is situated 4–5 m above sea level, was experiencing a tropical, dry season with temperatures ranging from 26.2°C–32.8°C. Ðà Lat, situated at 1500–2000 m above sea level, was having temperate, dry season with lower temperatures, ranging from 10.5°C–18.0°C. The high temperatures and low elevation in Thù Ðúc Province led to slow vegetative growth for all of the plants from the two different clones and the artemisinin contents were significantly reduced. The temperate environment of Ðà Lat supported robustly growing plants, with plant heights and branch lengths 4–5 times taller and longer that those planted at Thù Ðúc Province. The artemisinin contents of A. annua planted at Ðà Lat were 3–4 times greater than those cultivated at Thù Ðúc Province. Hence, this study indicated that the variations observed in plant growth and artemisinin contents were due to temperature effects because the two selected clones were genetically homogenous. The cold weather of Ðà Lat was suitable for planting of A. annua as opposed to the tropical weather of Thù Ðúc Province.
Aquaculture activity has increased the population of crab, hence increasing the generation of related wastes, particularly the shell. In addition, the number of molting process in crabs compounds further the amount of waste shell generated. As such, in the present work, the application of the waste crab shell as a source of CaO in transesterification of palm olein to biodiesel (methyl ester) was investigated. Preliminary XRD results revealed that thermally activated crab shell contains mainly CaO. Parametric study has been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 4 wt. %; and reaction temperature, 338 K. As compared to laboratory CaO, the catalyst from waste crab shell performs well, thus creating another low-cost catalyst source for producing biodiesel as well as adding value to the waste crab shell. Reusability of crab shell CaO has also been studied and the outcome confirmed that the catalyst is capable to be reutilized up to 11 times, without any major deterioration.
A recent rise in crab aquaculture activities has intensified the generation of waste shells. In the present study, the waste shells were utilized as a source of calcium oxide to transesterify palm olein into methyl esters (biodiesel). Characterization results revealed that the main component of the shell is calcium carbonate which transformed into calcium oxide when activated above 700 degrees C for 2 h. Parametric studies have been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 5 wt.%; reaction temperature, 65 degrees C; and a stirring rate of 500 rpm. The waste catalyst performs equally well as laboratory CaO, thus creating another low-cost catalyst source for producing biodiesel. Reusability results confirmed that the prepared catalyst is able to be reemployed up to 11 times. Statistical analysis has been performed using a Central Composite Design to evaluate the contribution and performance of the parameters on biodiesel purity.
The use of pseudo-infinite methanol in increasing the rate of esterification and transesterification reactions was studied using oil palm trunk (OPT) and sugarcane bagasse (SCB) derived solid acid catalysts. The catalysts were prepared by incomplete carbonisation at 400°C for 8h, followed by sulfonation at 150°C for 15h and characterised using TGA/DTA, XRD, FT-IR, SEM-EDS, EA and titrimetric determinations of acid sites. Under optimal reaction conditions, the process demonstrated rapid esterification of palmitic acid, with FAME yields of 93% and 94% in 45min for OPT and SCB catalysts, respectively. With the process, moisture levels up to 16.7% accelerated the conversion of low FFA oils by sulfonated carbon catalysts, through moisture-induced violent bumping. Moisture assisted transesterification of palm olein containing 1.78% FFA and 8.33% added water gave FAME yield of 90% in 10h, which was two folds over neat oil.
The aqueous methanolic extracts of Melastoma malabathricum L. exhibited antibacterial activity when assayed against seven microorganisms by the agar diffusion method. Solvent fractionation afforded active chloroform and ethyl acetate fractions from the leaves and the flowers, respectively. A phytochemical study resulted in the identification of ursolic acid (1), 2α-hydroxyursolic acid (2), asiatic acid (3), β-sitosterol 3-O-β-D-glucopyranoside (4) and the glycolipid glycerol 1,2-dilinolenyl-3-O-β-D-galactopyanoside (5) from the chloroform fraction. Kaempferol (6), kaempferol 3-O-α-L-rhamnopyranoside (7), kaempferol 3-O-β-D-glucopyranoside (8), kaempferol 3-O-β-D-galactopyranoside (9), kaempferol 3-O-(2″,6″-di-O-E-p-coumaryl)-β-D-galactopyranoside (10), quercetin (11) and ellagic acid (12) were found in the ethyl acetate fraction. The structures of these compounds were determined by chemical and spectral analyses. Compounds 1-4, the flavonols (6 and 11) and ellagic acid (12) were found to be active against some of the tested microorganisms, while the kaempferol 3-O-glycosides (7-9) did not show any activity, indicating the role of the free 3-OH for antibacterial activity. Addition of p-coumaryl groups results in mild activity for 10 against Staphylococcus aureus and Bacillus cereus. Compounds 2-5, 7 and 9-12 are reported for the first time from M. malabathricum. Compound 10 is rare, being reported only once before from a plant, without assignment of the double bond geometry in the p-coumaryl moiety.