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Abstract: The process of methanol synthesis based on the hydrogenation of CO2 was investigated over binary Cu/ZnO catalyst materials, prepared by applying a novel electroless plating fabrication method. The activity of the produced catalytic samples was determined at temperature range between 200 and 300 °C and the feedstock conversion data were supplemented with a detailed microstructure analysis using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and Cu and Zn K-edge, X-ray absorption near-edge structure (XANES) measurements and extended X-ray absorption fine-structure (EXAFS) measurements. It was confirmed that the disorder in the Cu crystallites created unique geometrical situations, which acted as the additional reactive centres for the adsorption of the reactant molecule species. Copper and zinc structural synergy (spill-over) was also demonstrated as being crucial for the carbon dioxide’s activation. EXAFS and XANES results provide strong evidence for surface alloying between copper and zinc and thus the present results demonstrate new approach applicable for explaining metal–support interactions.
Keywords: EXAFS, CuZn alloy, Spillover mechanism, CO2 valorization, Electroless deposition method, Heterogeneous catalysis
Published in RUNG: 12.04.2019; Views: 3580; Downloads: 0
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Abstract: Odmev na intervju z dr. Danilom Zavrtanikom, rektorjem Univerze v Novi Gorici, in sicer v sklopu štirih prispevkov pod naslovom Univerza in kampus v solkanskem kamnolomu.
Keywords: univerza, lokacija, kamnolom, Solkan, geografsko vozlišče, zahodna narodnostna meja, reka Soča
Published in RUNG: 10.04.2019; Views: 3103; Downloads: 125
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Abstract: During their life, birds face several challenges which can threaten the stability of physiological functions. These situations typically trigger a cascade of endocrine secretions involving the hypothalamic–pituitary–adrenal (HPA) axis, and resulting in the release of both cortisol and corticosterone also in birds. The use of a non-invasive approach to collect samples of biological material derived from natural populations represents a greatly combination for an improvement of knowledge avoiding handling animals. Steroid concentrations in feathers are mainly acquired from the capillary around the follicle during the long period of feather grown reflecting their bloodstream concentrations. Accordingly, a chronic HPA axis activation could be assessed using molted feathers cortisol concentrations. Another hormone, dehydroepiandrosterone (DHEA), is secreted by adrenals and it could be assessed in molted feathers. This study was aimed to evaluate the feasibility of using feathers cortisol and DHEA concentrations to provide a retrospective assessment of the activity of the HPA axis in griffon vulture acquired for health monitoring purposes. For this, we introduced two groups of animals with a known health condition: one group composed by griffons that have experienced a long-term physiologically compromised period (PC group; n=8) and the other group composed by griffons physiologically not compromised (CTRL group; n=9). The feathers cortisol and DHEA analyses were carried out using RIA [1,2] adapted for feathers. The results revealed different feather hormone concentrations between the two groups of animals. The feathers cortisol had a median value higher in the PC group than in the CTRL group, with cortisol concentrations showing a central value 1.6 times higher in those animals that suffered a long-term physiological impairment. The PC group showed also (Kruskal- Wallis test) higher feather concentrations of DHEA (P=0.01) than the CTRL group. Pearson’s correlation coefficients were used to examine the associations between cortisol and DHEA, showing no correlation between cortisol and DHEA feather concentrations in the PC group (r=0.18, P=0.34) and a moderate positive correlation in the CTRL group (r=0.51, P=0.011). In conclusion, our study reveals that molted feathers can be an interesting way to evaluate the physiological status of wild animals by using a non-invasive approach. Our analyses reveal that in addition to cortisol also DHEA could be evaluated to better understand the relationships between these hormones and to determine the resilience condition of wild species.
Keywords: CORTISOL, DHEA, GRIFFON VULTURE, Gyps fulvus, FEATHER
Published in RUNG: 09.04.2019; Views: 3102; Downloads: 0
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Abstract: The current 30% of canine perinatal mortality (Tonnessen et al., 2012) claims the need to deepen the knowledge about this phase, characterized by long-term hormonal and metabolic changes, that could benefit of long time-frame methods of investigation, reducing the quantity of samplings and thus respecting animal welfare (Veronesi et al., 2015). Indeed, apart from the well-known invasiveness of blood samplings, the necessary repeated collection of feces, urine and saliva, providing punctual information, could be stressful for the newborns and their mothers with negative effects on health status and maternal behavior. Given that sexual steroid hormones were reported to have an influence on health outcomes and development already from the perinatal period (Frey et al., 2017), in this work 17-β-Estradiol (E2) and Testosterone (T) concentrations were assessed from the claws of dogs up to 60 days of age, to identify possible endogenous biomarkers. Ten male and 10 female puppies, viable and healthy, born by elective cesarean section, were enrolled. Samplings were performed by trimming claws at birth, and the regrowth at 30 and 60 days of age after the breeder or the owner signed an informed consent. Then, E2 and T concentrations were analyzed by RIA (Veronesi et al., 2015) and a possible effect of gender evaluated by ANOVA. All the hormonal claws concentrations showed a significant (p<0.001) drop from birth to 30 and 60 days of age, while no significant changes were observed between 30 and at 60 days of age (Table 1). No influence of the newborns’ gender was found. Because of the higher levels of E2 and T observed at birth and at 30 days of age, it could be supposed that a source of production could be the placental and maternal compartments. However, the direct involvement of the fetus itself could not be excluded, given the reported accumulation from the nail capillary bed of those hormones (de Berker et al., 2007) and the production of sexual steroid hormones by feline fetal gonads (Braun and Jewgenow, 2017).
Keywords: Dog, Puppy, Claws, 17-ß-Estradiol, Testosterone.
Published in RUNG: 09.04.2019; Views: 3190; Downloads: 0
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Abstract: Hypothalamus-pituitary-adrenal (HPA) axis of both mother and fetus, is one of key mechanisms involved in fetal programming. Cortisol, the end-product of this axis, plays a critical role in regulating fetal and new-born metabolism and development. The aim of the study was to evaluate maternal and fetal cortisol concentrations shortly after delivery on hair samples non-invasively collected. The study was carried out on 11 pairs of beef cows and their calves (calves were 12 because of one case of twins) from the same farm and subjected to the same managerial conditions. Hair from new-born calves and from their mothers was collected on the day of birth shaving their withers to the level of the skin. The hair cortisol concentrations (HCC) were determined by RIA as previously described (Peric et al. 2013: J Dairy Sci 96:3023–3027). The results showed that fetal and maternal HCC ranged from 16.11 to 40.43 pg/mg and from 1.88 to 15.73 pg/mg respectively, with fetal and maternal mean ± SE HCC of 23.72 ± 2.21 and 6.40 ± 1.32 pg/mg respectively (p < 0.001). Fetal HCC were on average 3.5 higher than those of mothers but this ratio differed among the pairs. These differences were also found among the twin calves. These results indicate that in beef cows-and-calves pairs, although HCC at delivery were always higher in calves than in cows, the ratio between fetal and maternal HCC differs among pairs, suggesting an individuality in the fetal programming processes that may also rely on genetic and epigenetic factors.
Keywords: hair, cortisol, cattle, delivery
Published in RUNG: 09.04.2019; Views: 3457; Downloads: 0
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