| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme

Options:
  Reset


1 - 5 / 5
First pagePrevious page1Next pageLast page
1.
2.
The effect of nitrogen-ion implantation on the corrosion resistance of titanium in comparison with oxygen- and argon-ion implantations
T. Sundararajan, Zdravko Praunseis, 2004, original scientific article

Abstract: Commercially pure (CP) titanium was surface modified with nitrogen-, argon- and oxygen-ion implantations in order to investigate the material's corrosion resistance in a simulated body fluid. Five doses were chosen for the ions, ranging from 5.1015 cm-2 to 2.5-1017 cm-2. In-vitro open-cyclic potential-timemeasurements and cyclic polarization studies were carried out to evaluate the corrosion resistance of the modified surface in comparison to an unmodified surface. Specimens implanted at 4.1016 cm-2 and 7.1016 cm-2 showed the optimum corrosion resistance, higher doses showed a detrimental effect on the corrosion resistance. Argon- and oxygen-ion implantation at these doses did not show any improved corrosion resistance, indicating the beneficial role of nitrogen on the corrosion resistance of titanium in the simulated body-fluid environment. Grazing-incidence X-ray diffraction (GIXD) was employed on the implanted specimens to determine the phases formed with the increasing doses. X-ray photoelectron spectroscopy (XPS) studies on the passive film of the implanted samples and on the unimplanted samples were analyzed in order to understand the role of nitrogen in improving the corrosion resistance. The results of the present investigation indicated that nitrogen-ion implantation can be used as a viable method for improving the corrosion resistance of titanium. The nature of the surface and the reason for the variation and the improvement in the corrosion resistance are discussed in detail.
Keywords: metallurgy, ion implantation, orthopedic implants, corrosion, titanium, nitrogen, oxygen, argon
Published: 10.07.2015; Views: 1317; Downloads: 51
.pdf Full text (3,38 MB)
This document has many files! More...

3.
Modification of PET-polymer surface by nitrogen plasma
Rok Zaplotnik, Metod Kolar, Aleš Doliška, Karin Stana-Kleinschek, 2011, original scientific article

Abstract: Low pressure weakly nitrogen plasma was applied for incorporation of nitrogen-containing functional groups onto poly(ethylene terephthalate) - PET polymer. Nitrogen plasma was created in an electrode-less radiofrequency discharge at the nominal power of 200 W and the frequency of 27.12 MHz. Nitrogen molecules entered the discharge region were highly excited, partially dissociated and weakly ionized. Transformation into the state of plasma allowed for creation of chemically reactive particles with a high potential energy while the kinetic energy remained close to the value typical for room temperature. The chemical reactivity allowed for rapid functionalization with nitrogen-rich functional groups. The appearance of these groups was monitored by X-ray photoelectron spectroscopy - XPS. The polymer surface was quickly saturated with nitrogen indicating that the modification was limited to an extremely thin surface film.
Keywords: poly(ethylene terephthalate), nitrogen plasma, surface modification, functional groups, X-ray photoelectron spectroscopy
Published: 17.03.2017; Views: 329; Downloads: 61
.pdf Full text (150,48 KB)
This document has many files! More...

4.
Sweet maize growth and yield response to organic and mineral fertilizers, N rates and soil water regimes
Franc Bavec, Martina Bavec, Silva Grobelnik Mlakar, Milojka Fekonja, 2015, original scientific article

Abstract: Sweet maize is an underutilized vegetable in European temperate areas, and its consumption is increasing. For better understanding of cultivation practices, this pot experiment aimed to determine the eff­ects of diff­erent water regimes and nitrogen (N) rates calculated from N target values. N rates of 0 (control), 0.6 and 2 g N pot$^{-1}$ were applied as organic by-products pumpkin cake and pig manure digestate, and mineral fertilizers CAN 27 and ENTEC®26. Treatments of water supply were based on measured soil matric potentials of 2.8 pF (drought stress), 2.6 pF (optimal water) and 2.4 pF (overwatered). In comparison to mineral fertilizers, pumpkin cake proved to be equal in eff­ectiveness in plant height (155.8 cm), cob (85.8 g), green (124.9 g) and leaf mass per plant (44.2 g), or even better in root (72.3 g) and broom mass per plant (3.0 g). Yield parameters, cob mass (70.1 g), its length (6.3 cm) and diameter (2.0 cm), as well as the residual mineral N (59 mg N kg$^{-1}$) significantly increased at the highest N rate. Significantly lower values of the evaluated morphological parameters and photosynthetic rates (at brooming and harvesting) were associated with drought stress. The matric tension of 2.6 pF was established as an appropriate water regime for sweet maize growth.
Keywords: Zea mays L. saccharata Sturt., nitrogen, fertilizers, soil water potential, growth conditions
Published: 14.11.2017; Views: 567; Downloads: 204
.pdf Full text (257,82 KB)
This document has many files! More...

5.
Yield performance and agronomic efficiency in oil pumpkins (Cucurbita pepo L. group Pepo) depending on production systems and varieties
Manfred Jakop, Silva Grobelnik Mlakar, Martina Bavec, Martina Robačer, Tjaša Vukmanič, Urška Lisec, Franc Bavec, 2017, original scientific article

Abstract: In 2013 and 2014, a long-term trial (which was established in 2007) was conducted at the University Agricultural Centre in Pivola near Hoče. It included different production systems (conventional, integrated, organic, biodynamic), carried out in a field trial with oil pumpkins. The aim of the research was to analyse the effects of different production systems, varieties (hybrid and population variety) and years of production, on formation of oil pumpkin yields. The agricultural practice has been carried out in accordance with the applicable legislations and standards for the individual production system. When sowing, before fertilizing with nitrogen in early June and after the harvest, the amount of soil mineral nitrogen was monitored. We evaluated the number and weight of harvestable, unripe and decayed fruits, and yield of oil seed pumpkins and calculated the agronomic efficiency of the applied nutrients. The results showed that the year of production, the production system and the variety have a significant effect on some fruit characteristics and the yield of oil pumpkin seeds. The content of soil mineral nitrogen in May and September was significantly influenced by the production system and the year. In June, only the production system had a significant effect. The hybrid significantly increased the yields of oil pumpkin seeds in all production systems, even in the year that was less suitable for production. The agronomic efficiency of the applied nutrients in the biodynamic and organic production system is higher or equal than in the conventional production system, similarly, agronomic efficiency is higher in the hybrid compared to the oldest population variety efficiently. A comparable oil pumpkin yield can be expected in biodynamic and organic production, when proper nutrition and well carried out cultivation practices are combined with a new variety, when compared to less sustainable production systems, which often cause damage to the environment.
Keywords: production systems, variety, oil pumkins, mineral nitrogen, agronomic efficiency, yield
Published: 10.10.2018; Views: 650; Downloads: 168
.pdf Full text (290,91 KB)
This document has many files! More...

Search done in 0.14 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica