When two sheets of graphene stack in a twisted bilayer graphene (tBLG) configuration, the resulting constrained overlap between interplanar 2p orbitals produce angle-tunable electronic absorption resonances. By applying a novel combination of multiphoton transient absorption (TA) microscopy and TEM, we resolve the electronic structure and ensuing relaxation by probing resonant excitations of si...

Formation of the hydrides of antimony arsenic, bismuth, germanium, lead, selenium, tellurium and tin by reaction with sodium tetrahydroborate0 affords an excellent method for the separation of these elements as gases from a wide range of matrices. Excellent low limits of detection are attained when this separation method is combined with atomisation of the hydride in a heated quartz tube in the...

The conventional method for the determination of mercury in clinical samples is cold vapor atomic absorption spectrometry. Sample digestion or pretreatment require large sample volume and long sample preparation time. The inductively coupled plasma mass spectrometry (ICP-MS) method developed in this study requires only 100 microL of sample with practically no preparation, except for dilution wi...

lead is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-br-padap)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the ph range 4.0-6.0 from a large volume of aqueous solutions of various samples with preconcentration factor of 60. after filtration, the solid mass consisting of the lead complex and naphthalene was dissolved with 5...

Laboratory measurements were performed to characterize the geometrical effects in the calibration of the NASA's cloud absorption radiometer (CAR). The measurements involved three integrating sphere sources (ISSs) operated at different light levels and experimental setups to determine radiance variability. The radiance gradients across the three ISS apertures were 0.2%-2.6% for different visible...

In order to compare and evaluate the atomization process occurring in several types of graphite furnaces for atomic absorption spectrometry, the authors estimated temporal variations in the gas temperature by using a two-line method under the assumption of a Bolzmann distribution. The atomization furnaces employed were a graphite tube, a graphite tube coated with pyrolitic carbon, a graphite tu...

This study aimed at determining blood concentrations of lead (B-Pb) and cadmium (B-Cd) in a group of 1215 healthy blood donors (895 males, 320 females) and 758 children (397 boys, 361 girls) aged 10 years, sampled in 1996-1998 in four districts of the Czech Republic. The analysis was performed using atomic absorption spectrometry. The median B-Pb values were lower in children (34 mg/L) than in ...