1. Design and initial testing of a maize cob collection systemBojan Dolšak, Anita Breznik, Klemen Kaučič, Nataša Imenšek, Marko Marčec, Peter Gselman, Jani Humar, Mitja Krajnc, 2024, original scientific article Abstract: Maize cobs are valuable plant residues that can be used for many different purposes, including as a renewable energy
source. Despite their value, maize cobs are still underutilized, mainly because people are not aware of their potential and
harvesting techniques for their collection are still being developed. Therefore, this research focused on finding the most suitable
energy- and time- efficient method for mechanical collection of maize cobs. Upgrading the combine harvester with an
additional hopper proved to be the most promising solution, as it allows harvesting and storage of maize grain and maize cobs
in one pass, while the harvesting time remains almost the same and the maize cobs are of good quality, as they do not fall on
the field. A prototype with enlarged openings in the straw walkers, an additional grab container for maize cobs, a transport
auger, a transport cleaning fan with built-in knives, a transport tube and some other assemblies was fabricated and used in
practice. The first test results are very encouraging (94.4%-96.0% purity of maize cobs) and the system has been patented as a
promising solution, especially in times when the environmental sustainability of the planet and energy independence are
becoming increasingly important.
Keywords: maize cobs, utilization, mechanical harvesting, combine harvester upgrade
Published in DKUM: 26.07.2024; Views: 85; Downloads: 14
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2. Analysis of seed-associated bacteria and fungi on staple crops using the cultivation and metagenomic approachesValerija Tkalec, Aleksander Mahnič, Peter Gselman, Maja Rupnik, 2022, original scientific article Abstract: One of the key factors afecting seed quality is microbial communities residing on and in the seeds. In this study, microbial populations of seeds of conventionally and organically produced wheat, barley, and maize were analyzed using two diferent approaches: the cultivation method and metagenomics. For cultivation, three basic media were used: DG18 (for fungi), and nutrient agar or tryptic soy agar supplemented with cycloheximide or nystatin (for bacteria). Metagenomic sequencing was performed using the Illumina MiSeq platform. A total of 452 bacterial isolates comprising 36 genera and 5 phyla and 90 fungal isolates comprising 10 genera and 3 phyla were obtained from the seed surfaces. Among bacteria, representatives from the genera Bacillus, Pantoea, Paenibacillus, and Curtobacterium predominated, and among fungi, Aspergillus predominated. A total of 142 fungal OTUs and 201 bacterial OTUs were obtained from all the samples. Proteobacteria, Firmicutes, Bacteroides, and Actinobacteria comprised most of the bacterial OTUs, and Ascomycota comprised most of the fungal OTUs. Only 3 fungal OTUs (representatives of Curvibasidium, Venturia, and Dermateaceae) were exclusively present only within seeds and not on the seed surfaces. Barley seeds had the highest microbial load and richness, whereas corn had the lowest. Wheat and barley shared a higher number of OTUs than either of them did with corn with higher overlap between conventionally grown cereals than between organically grown cereals. Some OTUs were farming specifc. This study demonstrates that the microbiome of cereal seeds is greatly dependent on the species of the host and is less afected by agricultural practices.
Keywords: Microbiota, Wheat, Barley, Corn, NGS, Culture
Published in DKUM: 05.07.2024; Views: 119; Downloads: 9
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3. Characterization of defects in PVD TiAlN hard coatingsPeter Gselman, Tonica Bončina, Franc Zupanič, Peter Panjan, Darja Kek-Merl, Miha Čekada, 2012, original scientific article Abstract: PVD hard coatings are continuously gaining their importance in different fields of applications. In industrial use, they are often exposed to corrosive environments. Hard coatings possess inherently good corrosion resistance, but the substrate-hard coating systems may suffer from a severe corrosion attack due to the defects (craters, pin holes) in the coatings. On the sites, where defects extend through the coating, pitting corrosion can take place. These sites are drawbacks in the applications of hard coating. A PVD TiAlN hard coating was prepared on cold-work, tool-steel (AISI D2) substrates by sputtering using unbalanced magnetron sources. The growth defects incorporated into the coating were studied after the deposition and corrosion experiments. We used two methods: (1) scanning electron microscopy (SEM) for general overview of the coating topography and 2D-characterization of defects, and (2) scanning electron microscopy with a focused ion beam (SEM-FIB) for making serial cross-sections through the selected defects in order to provide images for a 3D-reconstruction of defects. In this work we tried to investigate the formation of a defect at a specific location and findout whether the selected defect causes pitting corrosion.
Keywords: trde prevleke, PVD prevleke, defekti, jamičasta korozija, mikrostruktura, PVD hard coating, defect, pitting corrosion, microstructure
Published in DKUM: 10.07.2015; Views: 1437; Downloads: 102
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4. DEFEKTI PVD-PREVLEK IN NJIHOV VPLIV NA FIZIKALNO-KEMIJSKE LASTNOSTI SISTEMA PREVLEKA/PODLAGAPeter Gselman, 2014, doctoral dissertation Abstract: Trde zaščitne prevleke, izdelane po postopku fizikalnega nanašanja iz parne faze (PVD – angl. physical vapor deposition), so se izkazale za enega izmed najučinkovitejših načinov povečanja produktivnosti odrezovalnih postopkov, vendar njihov potencial še ni popolnoma izkoriščen. Med nanašanjem v njih nastajajo defekti, ki poslabšajo oprijemljivost prevlek na podlago, zmanjšujejo korozijsko obstojnost itd.
Kakovost trdih prevlek izboljšamo, če zmanjšamo koncentracijo defektov. To lahko naredimo le, če poznamo mehanizme njihovega nastanka. V disertaciji so opisani mehanizmi nastanka defektov v posameznih stopnjah priprave prevlek in njihov vpliv na fizikalno-kemijske lastnosti sistema prevleka/podlaga.
Defekti so bili analizirani v nanoplastni prevleki TiAlN/CrN, ki je bila nanesena na štiri vrste jeklenih podlag (ASP30, M2, D2 in 316L) v naprševalniku s štirimi neuravnoteženimi magnetronskimi izviri. Za preučevanje izvorov, mehanizma nastanka in vpliva defektov PVD-prevlek na fizikalno-kemijske lastnosti sistema prevleka/podlaga so bile uporabljene naslednje tehnike: optični mikroskop (OM), mikroskop na atomsko silo (AFM), vrstični elektronski mikroskop (SEM), fokusiran ionski curek (FIB), presevni elektronski mikroskop (TEM), energijsko-disperzijska spektroskopija (EDS), tribometer, 3D-profilometer in 3D-rekonstrucija iz SEM-posnetkov.
Ugotovljeno je bilo, da defekti v prevleki nastanejo predvsem zaradi geometrijskega senčenja, ki ga povzročajo topografske nepravilnosti na površini podlag, delci, ki so po čiščenju ostali na površini, ter delci, ki prispejo na površino podlag med pripravo prevlek (segrevanje, ionsko jedkanje, naprševanje). Kali defektov predstavljajo tudi sulfidni in oksidni nekovinski vključki. Na mestih sulfidnih vključkov v prevleki nastajajo kraterji in pore ne glede na vrsto jeklenih podlag in način jedkanja. Na intenzivno jedkanih oksidnih vključkih v prevleki nastanejo pore, medtem ko na blago jedkanih oksidnih vključkih prevleka raste nemoteno.
Najpogostejše topografske nepravilnosti na površini trdih prevlek so nodularni defekti. Ti imajo tudi največji vpliv na povečanje površinske hrapavosti prevleke. Ugotovljeno je bilo tudi, da med tribološkim testom (angl. pin-on-disk) nastanejo prve poškodbe prevleke na mestih nodularnih defektov. Ti defekti so v začetni fazi tribološkega testa glavni vir abrazivnih delcev, ki povzročijo začetek obrabe prevleke. Izkazalo se je, da korozijsko obstojnost sistema prevleka/podlaga poslabšajo le tisti defekti, ki omogočajo elektrolitu prosto pot do podlage.
Keywords: defekti, PVD-prevleka, jamičasta korozija, nekovinski vključki v jeklu
Published in DKUM: 30.10.2014; Views: 3177; Downloads: 466
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5. RAZVOJ IN NAČRTOVANJE PROIZVODNJE MEDICINSKEGA VOZIČKAPeter Gselman, 2010, undergraduate thesis Abstract: V diplomski nalogi je predstavljeno majhno družinsko podjetje Gselman & Gselman d.o.o., ki je ob moji pomoči razvilo in v proizvodnjo implementiralo nov produkt - medicinski voziček.
Najprej je bil izveden sistematičen razvoj, ki sestoji iz iskanja idej in konstruiranja izdelka. Sledilo je načrtovanje proizvodnje in kalkulacija lastne cene vozička. Na koncu je bil izračunan poslovni izid celotnega projekta za obdobje 3 let.
Keywords: razvoj izdelka, konstruiranje izdelka, načrtovanje proizvodnje, delovni potek, delovna risba, lastna cena
Published in DKUM: 30.08.2010; Views: 2441; Downloads: 455
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