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Composition and morphology of diborides in Al-Ti-B alloys after annealing at 1873 K
Franc Zupanič, 2008, izvirni znanstveni članek

Opis: In the investigation, Al-Ti-B alloys with different Ti/B ratios were annealed at 1873 K for 10 hours. Under this condition diboride particles were in contact with molten aluminium. During annealing considerable growth of remaining unmelted diboride particles took place. The composition of diboride particles shifted extremely close to the composition of pure TiB2 regardless of the Ti/B ratios in the alloys, indicating that in equilibrium almost pure TiB2 coexisted with a melt. Diboride particles were bound with well-defined crystal facets. Types and relative size of the facets depended on the Ti/B ratio. It is strongly indicated that an excess of Ti (B) in the melt over that needed to form TiB2 stabilizes crystal planes having planar arrangement of Ti (B) atoms.V tej raziskavi smo več zlitin Al-Ti-B, ki so imele različna razmerja Ti/B, žarili 10 ur pri 1873 K. V teh razmerah so bili delci diborida v kontaktu z aluminijevo talino. Med žarjenjem so diboridni delci močno zrasli. Njihova sestava se je v vseh raziskanih zlitinah močno približala sestavi čistega TiB2, kar kaže, da je v termodinamskem ravnotežju s talino praktično čisti TiB2. Diboridni delci so bili obdani s kristalnimi fasetami. Vrsta in relativna velikost faset je bila močno odvisna od razmerja Ti/B. Obstajajo trdni dokazi, da presežek Ti (B) nad vrednostjo, ki je potrebna za tvorbo TiB2, stabilizira kristalne ravnine, ki imajo ravninsko razporeditev Ti (B) atomov.
Ključne besede: Al-Ti-B alloys, diboride phase, high-temperature annealing, morphology, microstructure
Objavljeno: 31.05.2012; Ogledov: 962; Prenosov: 15
URL Povezava na celotno besedilo

Wet-phase-separation membranes from the polysulfone/N,N-dimethylacetamide/water ternary system: the formation and elements of their structure and properties
Črtomir Stropnik, Vladimir Kaiser, Vojko Musil, Milan Brumen, 2005, izvirni znanstveni članek

Opis: Asymmetric and porous polysulfone (PSf) membranes were prepared by wet phase separation. Binary (PSf)/N,N-dimethylacetamide (DMA) solutions with polymer concentrations of 12.5-30 wt % were cast in thicknesses of 80-700 m and immersed in a coagulation bath of pure water. The morphology of the formed membranesć cross sections consisted of a cellular structure and macrovoidsč the cellular structure density was highest when the cast solution contained about 21 wt % PSf, regardless of the cast thickness. The membranesć pure waterpermeability decreased as the cast thickness increased. The instantaneousonset of the turbidity, regardless of the PSf content and cast thickness, its steep growth, and relatively high end value were the main characteristics of the turbidity phenomena taking place during the formation of the protomembranes. Again, the membrane-forming system with a PSf/DMA solution with about 21 wt % polymer, regardless of the cast thickness, had thehighest turbidity end value. The shrinkage of the cast solutions into the corresponding protomembrane was also examined quantitatively. Inverse experiments showed that the direction of the gravitation field had no influence on the shrinkage of the membrane-forming ternary system or the membranesć morphology and its water permeability.
Ključne besede: polymeric membranes, polysulfone asymmetric porous membranes, wet-phase separation, membrane preparation, morphology
Objavljeno: 01.06.2012; Ogledov: 1151; Prenosov: 51
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The influence of enzymatic treatment on wool fibre properties using PEG-modified proteases
Suzana Jus, Marc Schroeder, Georg M. Gübitz, Elisabeth Heine, Vanja Kokol, 2007, izvirni znanstveni članek

Opis: The main contribution of the presented work was to introduce the use of proteases modified with the soluble polymer polyethylene glycol (PEG) in the bio-finishing process of wool fibres, to target enzyme action to the outerparts of wool fibres, i.e. to avoid the diffusion and consequent destroying of the inner parts of the wool fibre structure, in the case of native proteases using. Different proteolytic enzymes from Bacillus lentus and Bacillus subtilis in native and PEG-modified forms were investigated and their influence on the modification of wool fibres morphology surface, chemical structure, as well as the hydrolysis of wool proteins, the physico-mechanical properties, and the sorption properties of 1:2 metal complex dye during dyeing were studied. SEM images of wool fibres confirmed smoother and cleaner fibre surfaces without fibre damages using PEG-modified proteases. Modified enzyme products have a benefit effect on the wool fibres felting behaviours (14%) in the case when PEG-modified B. lentus is used, without markedly fibre damage expressed by tensile strength and weight loss ofthe fibre. Meanwhile the dye exhaustion showed slower but comparable level of dye uptake at the end of the dyeing.
Ključne besede: volnena vlakna, proteolitski encimi, encimske modifikacije, sorpcija barve, morfologija vlaken, wool fibres, proteolytic enzymes, enzyme modification, felting, dye sorption, protein hydrolysis, XPS-analysis, fibre morphology
Objavljeno: 01.06.2012; Ogledov: 1666; Prenosov: 65
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Larval morphology of the antlion Neuroleon microstenus (McLachlan, 1898) (Neuroptera, Myrmeleontidae), with notes on larval biology
Dušan Devetak, Saška Lipovšek Delakorda, Maria Anna Pabst, 2010, izvirni znanstveni članek

Opis: Laval stages of the Mediterranean antlion species Neuroleon microstenus (McLachlan) are described and illustrated. Larvae do not build pitfall traps. They pursue prey by digging in sand backwards and waiting a prey. Second and third instar larvae move backwards or forwards on sand surface, whilst first instar larvae only forwards. Characteristic for the larvae of N. microstenus - like for other non-pit-builders - are prominent eye tubercles and sparse mandibular bristles. On the abdominal tip two bulges occur, each with four digging bristles. On the dorsal side of the head of second and third instar larvae black pigmentation occur forming "V" mark. Campaniform sensilla, sensilla coeloconica and sensilla basiconica are recognized for the first time in antlion larvae.
Ključne besede: zoology, antlions, morphology
Objavljeno: 07.06.2012; Ogledov: 1284; Prenosov: 92
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Raziskave interakcij med celicami in biopolimernimi materiali z naprednimi eksperimentalnimi metodami kot osnova za študij biokompatibilnosti polimerov
Rok Podlipec, 2015, doktorska disertacija

Opis: The last two decades have been determined by the development in the field of tissue engineering. Beside the constant progress in new biomaterials and scaffold fabrication methods, currently the main focus is to understand scaffolds biocompatibility. In our thesis, physical aspects of scaffold biocompatibility were studied by correlating molecular to macro scale physical properties of scaffolds with cell attachment and cell growth. In order to focus on scaffold physical properties, scaffolds were prepared by the same chemical composition of natural polymer gelatin excluding biochemical effects on the cell response. Scaffold with different physical properties were obtained by changing the temperature, pH and crosslinker degree during the cryogelation and populated by the fibroblast cells. Advanced experimental biophysical methods were applied to determine the polymer mobility via electron paramagnetic resonance (EPR) with spin labelling, the scaffold mechanical properties via rheometry, dynamic mechanical analysis (DMA) and nanoindentation using atomic force microscope (AFM) and the scaffold porosity via confocal fluorescence microscopy (CFM). The anisotropy of the molecular mobility of the side chains of polymers in the crosslinked gelatin structure was found to correlate with the initial cell growth (throughout the first week) the best of all the physical properties measured. About five times less efficient cell growth was measured on the scaffolds with highly mobile, spatially nonrestricted dynamics of the polymer side chains, in comparison with cell growth on the scaffolds with the restricted rotational motion of polymers. The result indicates that cells identify and respond to the degree of polymer mobility, where partially immobile phase is necessary for efficient cell attachment and efficient cell growth. So far, the molecular mobility of polymers constituting tissue engineering materials has never been studied thoroughly with respect to its influence on cell response, and therefore may represent a new experimental approach in understanding biocompatibility. To further understand cell-scaffold interaction, the study focused also on the first events during cell attachment - bond formation between the cell surface proteins and the specific binding sites on the material. In our thesis, cell adhesion dynamics was investigated in real-time on the surfaces of gelatin scaffolds with different physical properties using spatially-controlled cell manipulation by the optical tweezers and the confocal fluorescence microscopy detection. Our goal was to elucidate, if the adhesion dynamics can be correlated with cell growth and if it can be dependent on the scaffold polymer molecular mobility. Quantitative characterization of the optical tweezers force applied during cell-scaffold adhesion analysis was done by viscous drag force calibration and dynamic cell sequential trapping of individual cells. The maximal force on a trapped cell not causing the thermal damage was measured up to 200 pN, with nearly linearly increasing force profile across the cell towards the plasma membrane. By submicron spatial resolution of cell manipulation, we managed to quantify probability of cell adhesion, cell adhesion strength and mechanism of cell attachment, including the formation of the membrane tethers, which slow down the adhesion process. Adhesion strength was classified according to the displacement of the attached cell under the force of optical tweezers measured in the direction of the scaffold surface.Cell adhesion was shown to significantly correlate with cell growth in the first days of culture, while the adhesion itself seems to be dependent on the molecular mobility of surface polymers. The result indicates that the interactions during the first seconds may markedly direct further cell response. The developed methodology for cell adhesion analysis on the surfaces of 3D scaffolds serves as a good tool to forecast scaffold biocompatibility.
Ključne besede: polymer molecular mobility, mechanical response, morphology, scaffold biocompatibility, cell growth, single cell manipulation, cell adhesion dynamics, optical tweezers, electron paramagnetic resonance, dynamical mechanical analysis, nanoindentation, fluorescence microscopy and microspectroscopy
Objavljeno: 06.10.2015; Ogledov: 1063; Prenosov: 74
.pdf Celotno besedilo (5,95 MB)

Detection of planar points for building extraction from LiDAR data based on differential morphological and attribute profiles
Domen Mongus, Niko Lukač, Denis Obrul, Borut Žalik, 2013, objavljeni znanstveni prispevek na konferenci

Opis: This paper considers a new method for building-extraction from LiDAR data. This method uses multi-scale levelling schema or MSLS-segmentation based on differential morphological profiles for removing non-building points from LiDAR data during the data denoising step. A new morphological algorithm is proposed for the detection of flat regions and obtaining a set of building-candidates. This binarisation step is made by using differential attribute profiles based on the sum of the second-order morphological gradients. Any distinction between flat and rough surfaces is achieved by area-opening, as applied within each attribute-zone. Thus, the detection of the flat regions is essentially based on the average gradient contained withina region, whilst avoiding subtractive filtering rule. Finally, the shapes of the flat-regions are considered during the building-recognition step. A binary shape-compactness attribute opening is used for this purpose. The efficiency of the proposed method was demonstrated on three test LiDAR datasets containing buildings of different sizes, shapes, and structures. As shown by the experiments, the average quality of the buildings-extraction was more than 95%, with 96%correctness, and 98%completeness. In terms of quality, this method is comparable with TerraScan R , but both methods significantly differ when comparing correctness and completeness of the results.
Ključne besede: LiDAR, mathematical morphology, segmentation, DAP, DMP, building extraction
Objavljeno: 10.07.2015; Ogledov: 628; Prenosov: 263
.pdf Celotno besedilo (2,85 MB)
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Larval morphology of the antlion Myrmecaelurus trigrammus (Pallas, 1771) (Neuroptera, Myrmeleontidae), with notes on larval biology
Dušan Devetak, Vesna Klokočovnik, Saška Lipovšek Delakorda, Elisabeth Bock, Gerd Leitinger, 2013, izvirni znanstveni članek

Opis: Morphology and behaviour of third instar larvae of the Holomediterranean antlion species Myrmecaelurus trigrammus (Pallas) are described. Larvae are facultative pit-builders, they either ambush their prey at the surface, or dig pitfall traps that prey fall in to. Dark brown spots on dorsal and ventral sides of the head and on dorsal side of the thorax are charac-teristic of the larvae. Eye tubercles are not prominent. Jaws are equipped with long bristles, campaniform sensilla, sensilla coeloconica, and digitiform sensilla. A unique feature is the shape of the tips of all three teeth that is screw-like with a polyhedral surface. The body surface is covered with longitudinally grooved bristles and plumose hairs. On the tip of the antennae and on terminal and subterminal parts of labial palps sensilla basiconica occur. On the 9th abdominal segment there are two bulges, each of them bearing four digging bristles. Non-prominent eye tubercles and numerous mandibular bristles are morphological traits of pit-builders. Most of the behavioural traits are related to pit builders, whereas forward movement, waiting for prey without a pit and frequent changing of ambush location are traits of non-pit builders.
Ključne besede: zoologija, volkci, morfologija, Neuroptera, zoology, antlions, morphology, Neuroptera
Objavljeno: 10.07.2015; Ogledov: 775; Prenosov: 60
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The adhesion phenomena in polypropylene/wollastonite composites
Iztok Švab, Vojko Musil, Mirela Leskovac, 2005, izvirni znanstveni članek

Opis: Modification of polypropylene (PP) with wollastonite fillers was investigated in this paper. Three types of different silane pretreated wollastonite mineral filler were used for preparation of binary PP/wollastonite composites. The composite samples were homogenized in a Brabender Plasti-Corder kneading chamber and compression moulded into plates on a laboratory press. The adhesion between the wollastonite fillers used in this study and the PP matrix was predicted on the basis of the calculated adhesion parameters (work of adhesion, interfacial free energy and spreading coefficient) obtained by the surface free energy of pure materials. The contact angle method was used to determine surface free energy of components. The obtained values of adhesion parameters at the interface in the composites were correlated with mechanical properties as well as morphology observations of corresponding composites and were proved to be in relatively good agreement with the mechanical property measurements. Stronger adhesion in investigated composites has reflected in higher yield stress and tensile strength at break but in lower elongation at break and impact resistance.
Ključne besede: polypropylene composites, wollastonite, surface energy, adhesion, morphology, mechanical properties
Objavljeno: 10.07.2015; Ogledov: 728; Prenosov: 49
.pdf Celotno besedilo (498,06 KB)
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Morpho-agronomic characteristics of the interspecific hybrid Cucurbita ficifolia x C. maxima
Anton Ivančič, Metka Šiško, Borut Bohanec, Simona Šiftar, 2004, izvirni znanstveni članek

Opis: The aim of the investigation was to describe some of the main morpho-agronomiccharacteristics of the interspecific hybrid Cucurbita ficifolia x C. maxima, and to define the traits which can be used for distinguishing this hybrid from the parental species. The hybrid was obtained using emryo-rescue technique. The plants were extremely vigorous and were growing and flowering until the first frost. The ratio male versus was rangingbetween 1:40 and 1:80. Most of the male and female were sterile or partly sterile. The majority of the analysed traits were intermediate regarding the parental species. The most appropriate traits for the determination of the interspecific nature were the leaf margin, the shape and colour of ripe fruits and the shape of fruit stalks. The fruit exterior was extremely hard (similarly to the one of C. ficifolia) and cracked in several places.
Ključne besede: interspecific hybridisation, Cucurbita ficifolia, Cucurbita maxima, flowering, morphology
Objavljeno: 10.07.2015; Ogledov: 542; Prenosov: 13
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Microvoid system in fibres
Majda Sfiligoj-Smole, Diana Gregor-Svetec, 2002, izvirni znanstveni članek

Opis: The macrovoid system of poly(ethylene terephthalate) (PET) and poly(propylene) (PP) fibres was studied by small-angle x-ray scattering (SAXS). Commercial PET textile fibres were treated in different media and the influence on fibre homogeneity was followd by SAXS. PP technical fibres were manufactured on a laboratory spin-drawing device and subsequently drawn at different drawing conditions on a laboratory drawing device. The influence of drawing on the pore system was followed.
Ključne besede: textile industry, textile fibres, morphology, structure, investigations, SAXS, poly(ethylene terephtalate), PET, poly(propylene), PP, voids, microvoids
Objavljeno: 10.07.2015; Ogledov: 589; Prenosov: 45
.pdf Celotno besedilo (284,24 KB)
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