Silica-supported model copper catalysts were prepared by supporting bis(1,5-diphenyl-1,3,5-pentanetrionato)dicopper(II), Cu₂(dba)₂, on Cab-O-Sil by a batch impregnation technique. This metal complex showed a strong affinity for the silica support, developing monolayer coverages near the value predicted from a consideration of the size and shape of the planar metal complex (2.6 wt % Cu). The supported catalysts were subsequently activated by decomposing the organic ligands at 400 °C in air followed by reduction with 2% H₂/He at 250 °C. One sample was prepared having a loading of 3.70 wt % Cu₂(dba)₂/silica catalyst, and it was examined for the methanol synthesis reaction under the following conditions: 250 °C with an equimolar gas mixture of CO and H₂ in a high-pressure batch reactor. Kinetic data over the model catalyst were fit to a rate equation, second order in the limiting reactant (H₂), with a pseudo-second-order rate constant k₂[CO]_o[H₂]_o = 0.0957 [h-g total Cu]⁻¹. A control experiment using a commercial catalyst, Cu/ZnO/Al₂O₃ with a copper loading of 41.20 wt %, showed a value of k₂[CO]_o[H₂]_o = 0.793 [h-g total Cu]⁻¹. A fresh sample of Cu₂(dba)₂/silica was examined for methanol decomposition reaction at 220 °C. The model catalyst shows a methanol decomposition first-order rate constant greater than that of the commercial Cu/ZnO/Al₂O₃catalyst: 1.59 × 10^–1 [min-g total Cu]⁻¹ versus 9.6 × 10^–3 [min-g total Cu]⁻¹. X-ray diffraction analyzes confirm the presence of CuO particles in both catalysts after calcinations. Copper metal particles were found in both catalysts (fractional Cu dispersions were 0.11 and 0.16 on commercial and model catalysts, respectively) after the reduced catalysts were used in both the methanol synthesis and decomposition reactions. Using the values of copper dispersion found in these samples, we recalculated the rate constants for the two reactions per unit surface copper. These refined rate constants showed the same trends as those reported per total amount of Cu. One role of the promoter(s) in the commercial catalyst is the inhibition of the methanol decomposition reaction, thus allowing higher MeOH synthesis reaction rates in those regimes not controlled by thermodynamics.

Sri Lankan cinnamon germplasm is an underexploited genetic resource of high breeding potential. A representative collection of a cultivated cinnamon germplasm with 48 accessions, is established at the University of Ruhuna, Sri Lanka. From that collection, 40 three-year-old vegetative-propagated accessions, were used in this study to study the variations in plant morphology and leaf oil composition. Flush colour was determined as four main categories of pink, red, brown, and green in all 48 accessions. Leaf length, leaf width, leaf length to width ratio and petiole length varied from 7.9 to 14.5 cm, 3.8 to 7.3 cm, 1.8 to 3.07 cm, and 1 to 2.2 cm, respectively, in the selected 40 accessions. Both the good fragrant aroma category of bark fragrance and the sweet pungent category of bark taste were recorded in 21 of the 40 accessions. Twenty (20) accessions from above collection were selected for leaf oil analysis. Gas chromatography-mass spectrometry (GC-MS) of leaf oil revealed the presence of 146 chemical compounds. Eugenol was the major compound of 17 accessions (52.2% to 79.5%). Two accessions with zero eugenol contained 86.8% and 91.9% of benzyl benzoate (BB), in contrast to that of 0%-0.65% from other accessions. One accession produced 16.6% eugenol and 22.3% BB. A green flush colour associated with a higher BB percentage suggested a potential morphological marker for BB. The PCA for 20 accessions explained 88.11% of total variance. The cinnamon accessions with high BB, KA11 and GB17, were clustered together, and HB12 was isolated on a different cluster. Positive correlations were detected between linalool and β-caryophyllene (0.649), linalool and BB (0.770) (p < 0.01), and negative correlations between eugenol and linalool (-0.630) and eugenol and BB (-0.886) (p <0.01).

The influence of aqueous extract of millet on the crystallization and the dissolution of calcium oxalate (CaOx) crystals were investigated in detail under supersaturated and artificial urinary circumstances in order to understand the effect of the water-soluble components of millet on CaOx kidney stones in humans. To investigate the inhibition effect, different volumes of millet extract were added separately to the combined supersaturated and artificial urinary solutions while the crystal deposition process was monitored by UV-Vis and conductivity measurements. The harvested crystals were characterized by FT-IR, SEM, TGA, XRD and redox titrations so as to determine the structure and the morphology of CaOx crystals formed. Our findings indicate that the crystals obtained from inhibition and dissolution experiments were mainly calcium oxalate monohydrate (COM), the thermodynamically more stable phase. Furthermore, the results show that the millet extract has a promising inhibition effect in the supersaturated solution and in artificial urinary circumstances showing ~34 and ~26% decrease in crystal deposition, respectively, with 50 mL of millet extract compared to control experiments. The dissolution effect of millet extract is far superior to that of the inhibition effect. One gram of COM crystals completely disappeared when the crystals were washed ten times with 300 mL millet extracts. Under the same conditions, the control experiment showed only ~44% dissolution of COM crystals. Further investigations conducted with actual kidney stones under artificial urinary circumstances showed approximately 20% dissolution when washings were carried out using 300-mL portions of millet over one week. This novel finding may shed the light on the possible use of millet as a potential natural antiurolithic remedy to treat CaOx kidney stones in humans. Key words: Calcium oxalate, kidney stones, millet, inhibition, dissolution effect. The influence of aqueous extract of millet on the crystallization and the dissolution of calcium oxalate (CaOx) crystals were investigated in detail under supersaturated and artificial urinary circumstances in order to understand the effect of the water-soluble components of millet on CaOx kidney stones in humans. To investigate the inhibition effect, different volumes of millet extract were added separately to the combined supersaturated and artificial urinary solutions while the crystal deposition process was monitored by UV-Vis and conductivity measurements. The harvested crystals were characterized by FT-IR, SEM, TGA, XRD and redox titrations so as to determine the structure and the morphology of CaOx crystals formed. Our findings indicate that the crystals obtained from inhibition and dissolution experiments were mainly calcium oxalate monohydrate (COM), the thermodynamically more stable phase. Furthermore, the results show that the millet extract has a promising inhibition effect in the supersaturated solution and in artificial urinary circumstances showing ~34 and ~26% decrease in crystal deposition, respectively, with 50 mL of millet extract compared to control experiments. The dissolution effect of millet extract is far superior to that of the inhibition effect. One gram of COM crystals completely disappeared when the crystals were washed ten times with 300 mL millet extracts. Under the same conditions, the control experiment showed only ~44% dissolution of COM crystals. Further investigations conducted with actual kidney stones under artificial urinary circumstances showed approximately 20% dissolution when washings were carried out using 300-mL portions of millet over one week. This novel finding may shed the light on the possible use of millet as a potential natural antiurolithic remedy to treat CaOx kidney stones in humans. Key words: Calcium oxalate, kidney stones, millet, inhibition, dissolution effect.