Variation of different metabolites and heavy metals in Oryza sativa L., related to chronic kidney disease of unknown etiology in Sri Lanka

Chronic Kidney Disease of Unknown Etiology (CKDu) is a serious health problem in Sri Lanka. This disease is especially seen among lowland rice cultivators. Chemical stress factors such as pesticides and heavy metals can change the chemical composition and quantities of various metabolites in plants. Therefore, in this study phenolic compounds, free amino acid content and Chromium, Cadmium, Lead contents of rice grains were determined in CKDu prevalent areas. Furthermore, Chromium, Cadmium and Lead contents of cooked rice in CKDu prevalent areas were determined because they still use well water for cooking purposes and none of studies have been conducted to investigate the heavy metal contents of cooked rice. The total flavonoid contents of rice grains in highly CKDu affected areas are comparatively lower and has a significant negative correlation with Cadmium and Chromium contents in rice grains (P < 0.05). The Chromium, Cadmium and Lead contents of raw rice have been reduced during cooking process. Therefore, these heavy metal contents in cooking water are not sufficient to increase those heavy metal contents in cooked rice. However, the weekly intake of Chromium through cooked rice in CKDu prevalent area is higher than Povisional Tolerable Weekly Intake (PTWI) and weekly intake of Cadmium can exceed the PTWI with other foods rich with Cadmium. Therefore, this study suggested that total flavonoid content in rice grains is a important variation factor of CKDu prevalence and the chronic intake of Chromium and Cadmium contents may result kidney failure.

Dynamics of Cetyltrimethylammonium Bromide Head Groups in Bulk by Solid-State Deuterium NMR Spectroscopy

Variable temperature, solid-state deuterium (²H) NMR spectroscopy has been used to probe the rather complex head group dynamics of the surfactant cetyltrimethylammonium bromide- d₉ (CTAB- d₉) in bulk. Heating and cooling runs were made as the surfactant underwent supercooling. ²H NMR line shape simulations were used to identify the hierarchy of the molecular motions of CTAB as a function of temperature. Fast continuous methyl rotations about the N-C_methyl axes and 3-fold jumps about the main chain C-N axis were present at all of the temperatures from -40 to 120 °C. With heating, the spectra were consistent with CTAB molecules starting 180° flips about the hydrocarbon chain molecular axis around 0 °C, which continued to flip with increasing flip rates up to 80 °C. At 90 °C, the flips changed to rotation of the CTAB molecules about the hydrocarbon chain axis and that rotation continued to 120 °C. Comparison of spectra of bulk CTAB at different temperatures from heating and cooling runs revealed that the rotation about the long axis of the hydrocarbon chains started at around 90 °C on heating, however, it does not freeze out until between 70 and 80 °C because of supercooling.

“Decarbonization” of an imino-N-heterocyclic carbene ligand via triple benzyl migration from hafnium

Binding of an imino-N-heterocyclic carbene to tetrabenzylhafnium triggers complete removal of the carbene carbon via three successive benzyl migrations.