A METHOD FOR DETERMINATION OF SEPARATION PROPERTIES OF MEMBRANES

In this study, design of lab scale device for determination of separation properties of membranes is presented and analyzed. Device operates with different gas pressure between chambers, whereby gas streams perpendicular to the membrane. Using appropriate acquisition system and applying mathematical formulas, mechanism for gas transfer through the membrane is determinate. Polymer membranes based on zeolite are synthesized and tested by lab scale device. The membranes with various content of zeolite are tested with CO 2  gas until optimal composition of membrane components is established. Beside good mechanical and structural properties of applied membrane, suitable values of permeability with good agreement with the literature data are obtained

Hamiltonian walks on Sierpinski and n-simplex fractals

We study Hamiltonian walks (HWs) on Sierpinski and $n$--simplex fractals. Via numerical analysis of exact recursion relations for the number of HWs we calculate the connectivity constant $\omega$ and find the asymptotic behaviour of the number of HWs. Depending on whether or not the polymer collapse transition is possible on a studied lattice, different scaling relations for the number of HWs are obtained. These relations are in general different from the well-known form characteristic of homogeneous lattices which has thus far been assumed to hold for fractal lattices too.Comment: 22 pages, 6 figures; final versio

European beech stem diameter grows better in mixed than in mono-specific stands at the edge of its distribution in mountain forests

Recent studies show that several tree species are spreading to higher latitudes and elevations due to climate change. European beech, presently dominating from the colline to the subalpine vegetation belt, is already present in upper montane subalpine forests and has a high potential to further advance to higher elevations in European mountain forests, where the temperature is predicted to further increase in the near future. Although essential for adaptive silviculture, it remains unknown whether the upward shift of beech could be assisted when it is mixed with Norway spruce or silver fir compared with mono-specific stands, as the species interactions under such conditions are hardly known. In this study, we posed the general hypotheses that the growth depending on age of European beech in mountain forests was similar in mono-specific and mixed-species stands and remained stable over time and space in the last two centuries. The scrutiny of these hypotheses was based on increment coring of 1240 dominant beech trees in 45 plots in mono-specific stands of beech and in 46 mixed mountain forests. We found that (i) on average, mean tree diameter increased linearly with age. The age trend was linear in both forest types, but the slope of the age–growth relationship was higher in mono-specific than in mixed mountain forests. (ii) Beech growth in mono-specific stands was stronger reduced with increasing elevation than that in mixed-species stands. (iii) Beech growth in mono-specific stands was on average higher than beech growth in mixed stands. However, at elevations > 1200 m, growth of beech in mixed stands was higher than that in mono-specific stands. Differences in the growth patterns among elevation zones are less pronounced now than in the past, in both mono-specific and mixed stands. As the higher and longer persisting growth rates extend the flexibility of suitable ages or size for tree harvest and removal, the longer-lasting growth may be of special relevance for multi-aged silviculture concepts. On top of their function for structure and habitat improvement, the remaining old trees may grow more in mass and value than assumed so far.The authors would like to acknowledge networking support by the COST (European Cooperation in Science and Technology) Action CLIMO (Climate-Smart Forestry in Mountain Regions—CA15226) financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. This publication is part of a project that has received funding from the European Union’s HORIZON 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 778322. Thanks are also due to the European Union for funding the project ‘Mixed species forest management. Lowering risk, increasing resilience (REFORM)’ (# 2816ERA02S under the framework of Sumforest ERA-Net). Further, we would like to thank the Bayerische Staatsforsten (BaySF) for providing the observational plots and to the Bavarian State Ministry of Food, Agriculture, and Forestry for permanent support of the Project W 07 ‘Long-term experimental plots for forest growth and yield research’ (#7831-26625-2017). We also thank the Forest Research Institute, ERTI Sárvár, Hungary, for assistance and for providing observational plots. Furthermore, our work was partially supported by the SRDA via Project No. APVV-16-0325 and APVV-15-0265, the Ministry of Science and Higher Education of the Republic of Poland, the Project “EVA4.0” No. CZ.02.1.01/0.0/0.0/16_019/0000803 funded by OP RDE and the Project J4-1765 funded by the Slovenian Research Agency and also by the Bulgarian National Science Fund (BNSF) and the Project No. DCOST 01/3/19.10.2018

No systematic effects of sampling direction on climate-growth relationships in a large-scale, multi-species tree-ring data set

Ring-width series are important for diverse fields of research such as the study of past climate, forest ecology, forest genetics, and the determination of origin (dendro-provenancing) or dating of archaeological objects. Recent research suggests diverging climate-growth relationships in tree-rings due to the cardinal direction of extracting the tree cores (i.e. direction-specific effect). This presents an understudied source of bias that potentially affects many data sets in tree-ring research. In this study, we investigated possible direction-specific growth variability based on an international (10 countries), multi-species (8 species) tree-ring width network encompassing 22 sites. To estimate the effect of direction-specific growth variability on climate-growth relationships, we applied a combination of three methods: An analysis of signal strength differences, a Principal Component Gradient Analysis and a test on the direction-specific differences in correlations between indexed ring-widths series and climate variables. We found no evidence for systematic direction-specific effects on tree radial growth variability in high-pass filtered ring-width series. In addition, direction-specific growth showed only marginal effects on climate-growth correlations. These findings therefore indicate that there is no consistent bias caused by coring direction in data sets used for diverse dendrochronological applications on relatively mesic sites within forests in flat terrain, as were studied here. However, in extremely dry, warm or cold environments, or on steep slopes, and for different life-forms such as shrubs, further research is advisable.</p

Electrodeposition of Co-Ni-MoxOy Powders: Part I. The Influence of Deposition Conditions on Powder Composition and Morphology

The Co-Ni-MoxOy powders were obtained electrochemically at a constant current density from ammonia electrolyte. Ni and Co were anomalously deposited, inducing Mo deposition, which cannot be deposited separately from aqueous solutions. The obtained Co-Ni-MoxOy powders were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electon microscope (SEM) methods. Based on the obtained experimental results, it was concluded that the particle size of deposited powders is influenced by the chemical composition of the electrolyte and current density imposed. XRD results suggested that obtained powders were of amorphous structure, although a Co3Mo compound can be formed if certain experimental conditions are applied

Jet stream position explains regional anomalies in European beech forest productivity and tree growth.

The mechanistic pathways connecting ocean-atmosphere variability and terrestrial productivity are well-established theoretically, but remain challenging to quantify empirically. Such quantification will greatly improve the assessment and prediction of changes in terrestrial carbon sequestration in response to dynamically induced climatic extremes. The jet stream latitude (JSL) over the North Atlantic-European domain provides a synthetic and robust physical framework that integrates climate variability not accounted for by atmospheric circulation patterns alone. Surface climate impacts of north-south summer JSL displacements are not uniform across Europe, but rather create a northwestern-southeastern dipole in forest productivity and radial-growth anomalies. Summer JSL variability over the eastern North Atlantic-European domain (5-40E) exerts the strongest impact on European beech, inducing anomalies of up to 30% in modelled gross primary productivity and 50% in radial tree growth. The net effects of JSL movements on terrestrial carbon fluxes depend on forest density, carbon stocks, and productivity imbalances across biogeographic regions

Electrodeposition of co-ni-mo <inf>x</inf>o <inf>y</inf> powders: Part I. the influence of deposition conditions on powder composition and morphology

The Co-Ni-Mo xO y powders were obtained electrochemically at a constant current density from ammonia electrolyte. Ni and Co were anomalously deposited, inducing Mo deposition, which cannot be deposited separately from aqueous solutions. The obtained Co-Ni-Mo xO y powders were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electon microscope (SEM) methods. Based on the obtained experimental results, it was concluded that the particle size of deposited powders is influenced by the chemical composition of the electrolyte and current density imposed. XRD results suggested that obtained powders were of amorphous structure, although a Co 3Mo compound can be formed if certain experimental conditions are applied. © The Author(s) 2009

A comparative thermomagnetic study of melt-spun Nd-Fe-B alloys with different Nd content

Changes in the phase composition and magnetic properties of three types of commercial Nd-Fe-B alloys with different Nd content - low (10-12 wt%), near stoichiometric (21-25 wt%) and rich (26-29 wt%) caused by thermomagnetic analysis (TM) were observed in regard to optimal magnetic state. Phase compositions of investigated alloys before and after TM measurement up to 800°C were compared using 57Fe Mössbauer spectroscopy and X-Ray analysis. The TM measurements decompose all three materials and the main products of decomposition process α-Fe and Fe2B phase. Observed changes in structure and phase composition had direct influence on magnetic properties. Loss of magnetic properties induced by thermal decomposition is clearly illustrated on corresponding SQUID hysteresis loops