Determination of cotinine in biological fluids by capillary gas chromatography-mass spectrometry-selected-ion monitoring

A sensitive and selective method for the determination of cotinine in plasma and urine is presented. Quantitation is effected by capillary gas chromatography-mass spectrometry after liquid--liquid extraction of 0.25-1 ml of biological specimens with a trideuterated cotinine internal standard. The procedure is linear and has acceptable precision over the range of concentrations encountered in pharmacokinetic studies of nicotine or cotinine. The suitability of the assay is shown by a number of plasma concentration--time curves after a single oral or intravenous administration of cotinine to a human volunteer and after multiple-dose intravenous administration of nicotine.     

Organized growth of GaAs/AlAs lateral structures on atomic step arrays: What is possible to do?

Laterally modulated nanostructures, exhibiting large optical and electrical anisotropy, can be grown an vicinal surfaces. However the lateral organization of Ga and Al atoms is far from ideal. We discuss our way of understanding the growth of these structures.     

Fermi-edge singularities in AlxGa1-xAs quantum wells: extrinsic versus many-body scattering processes

A Fano resonance mechanism is evidenced to control the formation of optical Fermi-edge singularities in multisubband systems such as remotely doped AlxGa1-xAs heterostructures. Using Fano parameters, we probe the physical nature of the interaction between Fermi sea electrons and empty conduction subbands. We show that processes of extrinsic origin like alloy disorder prevail easily at 2D over multiple diffusions from charged valence holes expected by many-body scenarios.     

From Solid-Solution Electrodes and the Rocking-Chair Concept to Today's Batteries

Lithium-ion batteries (LIBs) have become ubiquitous power sources for small electronic devices, electric vehicles, and stationary energy storage systems. Despite the success of LIBs which is acknowledged by their increasing commodity market, the historical evolution of the chemistry behind the LIB technologies is laden with obstacles and yet to be unambiguously documented. This Viewpoint outlines chronologically the most essential findings related to today's LIBs, including commercial electrode and electrolyte materials, but furthermore also depicts how the today popular and widely emerging solid-state batteries were instrumental at very early stages in the development of LIBs.     

Self‐Assembly in Water of Poly(acrylic acid)‐Based Diblock Copolymers Synthesized by Nitroxide‐Mediated Polymerization

Summary: Amphiphilic diblock copolymers consisting of a hydrophilic block, poly(acrylic acid), and a hydrophobic block, polystyrene, were synthesized by direct nitroxide‐mediated polymerization using the PS block as a macro‐initiator for the first time. Several techniques were used to characterize the amphiphilic block copolymers (size exclusion chromatography, NMR spectroscopy). The proposed method can lead to samples with a broad range of composition and molar mass. Preliminary studies of their self‐assembly in aqueous medium using fluorescence spectroscopy and small‐angle neutron scattering are presented.

Schematic of the formation of the PS‐b‐PAA block copolymers and their micellization in aqueous media.     

Oxysulfure de scandium Sc2O2S

Sc₂O₂S is hexagonal, $\text{P6}{}_3\text{mmc}\text{, a = 3.5196(4)}$ Å, c = 12.519(2) Å, Z = 2, Dc = 3.807 g cm^?3, Dm = 4.014 g cm^?3, μ(MoKα) = 55.51 cm^?1. The final R value is 0.038 for 205 symmetry-independent reflections. This scandium oxysulfide has c = 12.52 Å, twice the value found in rare earth oxysulfides. An La₂O₂S cell combined with its reflection in a (001) mirror gives the Sc₂O₂S cell.