This study focuses on voltage cycling induced degradation of cathodes with different loading (0.4 and 0.1 mg Pt /cm 2 ) when applying square wave or triangular wave based accelerated stress tests (ASTs) between 0.6 and 1.0 V RHE . The degradation of the H 2 /O 2 and H 2 /air performance upon extended voltage cycling (up to 30000 cycles) was analyzed in terms of the voltage loss contributions from ORR kinetics, O 2 mass transport resistances and proton conduction resistances in the cathode. The extent of cathode thinning due to carbon support corrosion was determined by post mortem electrode thickness measurements. Square waves were found to cause a more rapid loss of ECSA and mass activity compared to triangular waves, which was shown to be due to the longer hold periods at high potentials rather than to the rate of the potential transient. The observed increase of the O 2 mass transport resistance with voltage cycling was found to mainly depend on the available Pt surface area, while mass transport resistances due to carbon corrosion were found to be insignificant. Finally, it was shown that by lowering the upper potential limit to 0.85 V RHE , low-loaded catalyst layers can sustain 30000 potential cycles without degradation of the H 2 /air performance. A comparison of the ECSA and the O 2 mass transport resistance evolution of MEAs aged by SW cycles leads to considerably faster degradation compared to TW cycles. To identify whether the fast po- tential transients or the potential hold phase is responsible for the faster degradation rates during SW aging, an additional procedure, consisting of a triangular potential scan followed by potential hold phase (TW-H) was tested. A comparison of the evolution of the cath- ode’s ECSA , mass activity, and mass transport resistance revealed that the potential hold rather than the rate of the potential transient is the main contributor to cathode aging in voltage cycling ASTs, so that SW and TW–H cycling profiles lead to identical aging rates with respect to the number of cycles. significant and concomitant

Introduction: Trigeminal neuralgia, also called 'tic douloureux', is a chronic pain condition that affects the trigeminal nerve and it is the most common cause of facial pain in adults. Gamma knife radiosurgery has been increasingly used in the treatment of medically refractory trigeminal neuralgia, as a non-invasive alternative to microvascular decompression and rhizotomies. Aim: The aim of this study was to determine the early efficacy of gamma knife radiosurgery in a group of patients with trigeminal neuralgia, treated in the Clinical Center of Serbia. Material and methods: We checked all the patients treated with gamma knife radiosurgery for trigeminal neuralgia at the Clinic of Neurosurgery at the Clinical Center of Serbia in Belgrade, in a period between the end of 2015 and beginning of 2018. They were examined after the first, third, sixth, ninth month and a year after the radiosurgery. Informations about the pain and its intensity, type and dosage of pharmacotherapy were collected. Surgery was considered successful if it reduced the pain for a minimum of 30% or led to the reduction of pharmacotherapy needed to control the pain in comparison to the dosages before surgery. Results: There was a trend of decreased efficacy that lasted for a year after the implementation of procedure, which, most likely, resulted from a short period of monitoring and assessment of the patient's condition. Conclusion: The results from this study show that gamma knife radiosurgery could be one of the options in treatment of trigeminal neuralgia.

Centaurea species are used in eastern Mediterranean ethnopharmacology as a result of varietes of bioactive compounds they comprise. Aim of this work was to characterize the Centaurea rupestris L. hydrodistilled essential oil chemical composition and test the biological activity: antimicrobial effect, antioxidant potential and inhibition of cholinesterases. Plant material authentication was done with chromosome number counting and genome size assessment with the flow cytometry. Hydrodistilled essential oils were characterised with gas chromatography/mass spectrometry technique GC-MS and GC-FID. The antimicrobial effect was tested using disk diffusion and microdilution methods methods, antioxidant potential was tested with DPPH and FRAP methods and cholinesterases inhibition was tested with Ellman method. Genome size for C. rupestris species: sample A presented 2C=3.60 (0.10) pg and sample B 2C=3.62 (0.08) pg. The chromosome number was 2n=20 for both samples. The main essential oil constituents in isolated sample A oil, detected with GC-MS and GC-FID were: germacrene D (24.3%), heptacosane (14.4%), phytol (6.7%), β- caryophyllene (5.0%) and pentacosane (4.5%). Sample B essential oil had the main constituents: hexadecanoic acid (18.7%), heptacosane (13.8%), α-linolenic acid (11.8%), nonacosane (7.8%) and germacrene D (5.4%). Both samples of oil showed broad spectrum antimicrobial effect with good activity against emerging Gram-positive and Gram- negative oportunistic pathogens and pathogenic fungi which indicates the pharmaceutical potential of the C. rupestris essential oil.