We report what is believed to be the first demonstration of diode-pumped continuous-wave (CW) thin-disk Yb3+-doped Gd2SiO5 (Yb:GSO) laser at 1048 nm. With a 3.8% output coupler, the maximum output power is 1.38 W under a pump power of 17.8 W. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a power of 337 mW at 524 nm by using a LiB3O5 (LBO) nonlinear crystal. At the output power level of 337 mW, the green power stability is better than 5% and the ellipticity of spot is 0.97.

Phenyl acetic acid, a metabolite of 2—phenyl ethylamine, acts as a neuromodulator in the nigrostriatal dopaminergic pathway neuromodulator stimulating the release of dopamine. The evaluation of phenyl acetic acid concentration in the biological fluid reflects phenyl ethylamine levels thus allowing the assessment of the modulatory role of this endogenous substance. Changes in biological fluids levels of 2—phenylethylamine and/or in its metabolite have been reported in affective disorders, such as depression and schizophrenia. Recently, the occurrence of the “attention deficit hyperactivity syndrome” has been frequently reported in childhood population and involvement of dopaminergic dysfunction in this disease has been suspected. A fast, reliable and reproducible method for the determination of phenyl acetic acid in human blood, is therefore needed in order to have a screening tool for monitoring both healthy childhood population and suspected “attention deficit hyperactivity syndrome” patients. The gas chromatographicmass spectrometric method here described makes use of a deuterated internal standard in order to overcome problems related to the lack of reproducibility often encountered when a derivatization step is performed.

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Efficient continuous‐wave (CW) intracavity frequency doubling of a diode‐end‐pumped Yb:GdYSiO2 (Yb:GYSO) laser operating on 2F5/2 → 2F7/2 transitions at 1081.5 nm has been demonstrated. With 17.6 W of diode pump power and the frequency doubling crystal LiB3O5 (LBO), a maximum output power of 3.76 W in the green spectral range at 541 nm has been achieved, corresponding to an optical‐tooptical conversion efficiency of 21.4%; the output power stability over 30 min is better than 5%. To the best of our knowledge, this is first work on intracavity frequency doubling of a diode pumped Yb:GYSO laser at 1081.5 nm. (© 2011 by Astro Ltd., Published exclusively by WILEY‐VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY‐VCH Verlag GmbH & Co. KGaA)