K x-ray emission spectra from natural silicates

Chemical shifts of Si Kα_1,2 and Al Kα_1,2 lines in seven natural silicates has been measured comparatively to the lines of the pure elements. An attempt is made to correlate these shifts to the surroundings of Si and Al in the minerals.     

Potassium barium bismuth oxide

KBa₄Bi₃O crystallizes in the centrosymmetric tetragonal space group I4/mcm. In this compound, bismuth is present as two anionic species, i.e. Bi₂^4? dumbbells [Bi—Bi 3.113 (3) Å] and isolated Bi^3?. Atom Bi1 (Bi^3?) lies inside a bicapped square antiprism (2 × K and 8 × Ba). Atom Bi2, which forms the Bi₂^4? dumbbell, sits inside a bicapped distorted trigonal prism (2 × K and 6 × Ba). O atoms occupy tetra­hedral voids between Ba atoms.     

Glutamatergic alterations in the cortex of genetic absence epilepsy rats

Background  

In absence epilepsy, the neuronal hyper-excitation and hyper-synchronization, which induce spike and wave discharges in a cortico-thalamic loop are suspected to be due to an imbalance between GABA and glutamate (GLU) neurotransmission. In order to elucidate the role played by GLU in disease outcome, we measured cortical and thalamic extracellular levels of GLU and GABA. We used an in vivo quantitative microdialysis approach (no-net-flux method) in an animal model of absence epilepsy (GAERS). In addition, by infusing labelled glutamate through the microdialysis probe, we studied in vivo glutamate uptake in the cortex and thalamus in GAERS and non-epileptic control (NEC) rats. Expression of the vesicular glutamate transporters VGLUT1 and VGLUT2 and a synaptic component, synaptophysin, was also measured.     

Laser spectroscopy investigation of the hyperfine structure of highly excited 2P32 states in alkali atoms

Highly excited ²P_{$\text{3}\text{2}$} levels in alkali atoms were populated using a multi-step excitation, involving a tunable dye laser. The hyperfine structure of the 9 ²P_{$\text{3}\text{2}$} level in ⁸⁷Rb and the 11, 12 ²P_{$\text{3}\text{2}$} levels in ¹³³Cs was determined with optical double resonance.