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Non-Contact Luminescence Lifetime Microthermometry using Scintillation Sensors

100%
Mykhaylyk V., Kraus H., Wagner A.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
1108-1111
EN
The paper describes an original technique for non-contact in situ monitoring of the temperature developed for experiments in a vacuum environment at the tender X-ray beamline I23 of the Diamond Light Source. The sample temperature is established by determining the luminescence decay constant of a Bi₄Ge₃O₁₂ (BGO) scintillation sensor. BGO is ideally suited for a temperature range of 30 K to 130 K, in which its decay constant shows a strong temperature dependence. The principle of the method, system design and application examples are discussed and the performance and potential of the technique is assessed.
2
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Fluoro-Jade and TUNEL staining as useful tools to identify ischemic brain damage following moderate extradural compression of sensorimotor cortex

100%
Kundrotiene J., Wagner A., Liljequist S.
Acta Neurobiologiae Experimentalis
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2004
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vol. 64
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issue 2
153-162
EN
Cerebral ischemia was produced by moderate compression for 30 min of a specific brain area in the sensorimotor cortex of Sprague-Dawley rats. On day 1, that is 24 h after the transient sensorimotor compression, ischemia-exposed animals displayed a marked focal neurological deficit documented as impaired beam walking performance. This functional disturbance was mainly due to contralateral fore- and hind-limb paresis. As assessed by daily beam walking tests it was shown that there was a spontaneous recovery of motor functions over a period of five to seven days after the ischemic event. Using histopathological analysis (Nissl staining) we have previously reported that the present experimental paradigm does not produce pannecrosis (tissue cavitation) despite the highly reproducible focal neurological deficit. We now show how staining with fluorescent markers for neuronal death, that is Fluoro-Jade and TUNEL, respectively, identifies regional patterns of selective neuronal death. These observations add further support to the working hypothesis that the brain damage caused by cortical compression-induced ischemia consists of scattered, degenerating neurons in specific brain regions. Postsurgical administration of the AMPA receptor specific antagonist, LY326325 (30 mg/kg; i.p, 70 min after compression), not only improved beam walking performance on day 1 to 3, respectively but also significantly reduced the number of Fluoro-Jade stained neurons on day 5. These results suggest that enhanced AMPA/glutamate receptor activity is at least partially responsible for the ischemia-produced brain damage detected by the fluorescent marker Fluoro-Jade.
3
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The Evidence of Quasi-Free Positronium State in GiPS-AMOC Spectra of Glycerol

88%
Zvezhinskiy D., Butterling M., Wagner A., Krause-Rehberg R., Stepanov S.
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vol. 125
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issue 3
821-824
EN
We present the results of processing of age-momentum correlation spectra that were measured for glycerol by the gamma-induced positron spectroscopy facility. Our research has shown that the shape of experimental s(t) curve cannot be explained without introduction of the intermediate state of positronium (Ps), called quasi-free Ps. This state yields the wide Doppler line near zero lifetimes. We discuss the possible properties of this intermediate Ps state from the viewpoint of developed model. The amount of annihilation events produced by quasi-free Ps is estimated to be less than 5% of total annihilations. In the proposed model, quasi-free Ps serves as a precursor for trapped Ps of para- and ortho-states.
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