Chemometrics aided energy dispersive X-ray fluorescence and scattering for diagnostic modeling of trace biometals as cancer biomarkers.

Direct analysis of biometals in biomedical samples by energy dispersive X-ray fluorescence (EDXRF) for disease diagnostics has hardly been fully explored due to dark matrix analytical challenges. In this study, we exploited multivariate chemometrics modeling of cancer diagnostics in model human tissue simulates and cultures using selected biometals' (Mn, Fe, Cu, Zn and Se) fluorescence and Compton scatter profiles. PCA successfully reduced the correlated data dimension to uncorrelated datasets for the characterization of the cell cultures.

X-ray fluorescence analysis of selected micronutrients in ten African indigenous leafy vegetables cultivated in Nairobi, Kenya.

Introduction: There is a growing interest on vital roles of micronutrients in the maintenance of good health and enhancement of the immune system for prevention of diseases.

Methods: Energy dispersive X-Ray fluorescence (EDXRF) spectrometer was used for qualitative and quantitative analysis of selected micronutrients Zinc (Zn), Iron (Fe), Magnesium (Mg), Calcium (Ca) and Potassium (K) in ten African indigenous leafy vegetables (AILVs) (Corchorus olitorius, Cucurbita moschata, Amaranthus blitum, Brassica carinata , Cleome gynandra, Solanum scabrum , Crotalaria ochroleuca, Urticadioica, Manihot esculenta, Vigna unguiculata) which are cultivated, marketed and consumed in Kenya and across East and West Africa.

Results: In this study, the highest levels of Calcium, Zinc and Iron were found in Urticadioica leaves (75.

Upper limits for undetected trace species in the stratosphere of Titan.

In this paper we describe the first quantitative search for several molecules in Titan's stratosphere in Cassini CIRS infrared spectra. These are: ammonia (NH3), methanol (CH3OH), formaldehyde (H2CO), and acetonitrile (CH3CN), all of which are predicted by photochemical models but only the last of which has been observed, and not in the infrared. We find non-detections in all cases, but derive upper limits on the abundances from low-noise observations at 25 degrees S and 75 degrees N.

The case of the weak N-X bond: Ab initio, semi-experimental, and experimental equilibrium structures of XNO (X = H, F, Cl, OH) and FNO2.

The equilibrium structures of FNO, ClNO, HONO, and FNO2 have been determined using three different, somewhat complementary methods: a completely experimental, a semi-experimental (where the equilibrium rotational constants are derived from the experimental effective ground-state rotational constants and an ab initio cubic force field), and an ab initio, where geometry optimizations are usually performed at the coupled cluster level of nonrelativistic electronic structure theory using small to very large Gaussian basis sets. For the sake of comparison, the equilibrium structures of HNO and N2O have also been redetermined, confirming and extending earlier results. The semi-experimental method gives structural parameters in good agreement with the reliable experimental results for each compound investigated.