1. Nanochemistry and Materials : a Laboratory ManualJanja Stergar, Irena Ban, 2022, higher education exercise book Abstract: The publication contains instructions for laboratory work in the subject Nanochemistry and Materials. Students are introduced to the experimental principles of nanochemistry in the laboratory. They learn about various synthesis and characterization methods, in conjunction with magnetic nanoparticles useful in biomedical and engineering applications. They learn about the safety of nanoparticles and their effects, impact on technology, and contribution to improving life on many levels when used properly. The instructions are written in English as they are intended for foreign students who choose the mentioned subject.
Keywords: magnetic nanoparticles, coprecipitation, microemulsion technique, X-Ray powder diffraction, dynamic light scattering
Published in DKUM: 29.08.2022; Views: 686; Downloads: 77
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2. Ammoniumbis(hydroxylammonium) pentafluoridooxidovanadate(IV) : synthesis and characterisation of a new fluorovanadateBrina Dojer, Matjaž Kristl, Zvonko Jagličić, Mihael Drofenik, Anton Meden, 2008, original scientific article Abstract: Turquoise crystals of a new hydroxylammonium compound with the formula $NH_4(NH_3OH)_2[VOF_5]$ have been synthesized by the reaction of solid $NH_3OHF$ and the aqueous solution of vanadium in HF. The compound crystallizes monoclinic, $P2_1/n$, with cell parameters: a = 10.5658(2) Å, b = 6.6143(1) Å, c = 11.6618(2) Å, β = 96.282(1). Magnetic susceptibility was measured using a SQUID device over a temperature range 2–300 K at magnetic field $10^3 Oe$ giving the result $µ_{eff}$ = 1.65 BM. The thermal decomposition was studied by TG and DSC analysis. $NH_4(NH_3OH)_2[OF_5V]$ decomposes above 354 K in three steps, obtaining $NH_4VOF_3$ after the first step and $V_2O_5$ as the final residue.
Keywords: hydroxylammonium fluorovanadates, x-ray powder diffraction, x-ray structure determination, thermal analysis
Published in DKUM: 17.08.2017; Views: 1850; Downloads: 110
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4. Fatigue properties of sintered DIN SINT-D30 powder metal before and after heat treatmentMarko Šori, Borivoj Šuštaršič, Srečko Glodež, 2014, original scientific article Abstract: The main focus of this study was to determine how heat treatment affects the dynamic properties of sintered steel. All the specimens were made of the DIN SINT-D30 metal powder, but only half of them were additionally heat treated. Flat specimens were cold pressed and sintered. The second set was additionally heat treated to increase the strength. After the static mechanical properties were determined, the fatigue strength was investigated in a pulsating machine with a load ratio of R = 0. Wöhler curves were plotted and the parameters for determining the fatigue life (of' and b) were calculated.
Keywords: powder metallurgy, fatigue, S-N curve
Published in DKUM: 16.03.2017; Views: 1400; Downloads: 122
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5. Water sorption characteristics of a new type of gelatine powder, produced by a new high-pressure micronisation processChristian Reibe, Željko Knez, 2010, original scientific article Abstract: A new high-pressure micronisation process for Gelatine has been developed. By applying this process to gelatine, a new type of Gelatine was produced: Dry and pure Gelatine powder of high molecular mass. This powder was investigated,regarding its sorption behaviour and compared to its feedstock material. The feedstock Gelatine was of type B 200 Bloom, 6 mesh, having a molecular mass of 150,000 g $mol^{-1}$. The produced Gelatine powder's molecular mass was around 130,000 g $mol^{-1}$, while its mean particle size was 300 μm. Their sorption isotherms were investigated at 30 °C, 40 °C and 60 °C and water activities in the range from 0.055 to 0.836. At given water activities the Equilibrium Moisture Contents (EMC) decreases with increasing temperature.The measured sorption isotherms were fit with the Brunauer- Emmet-Teller (BET)- model and the Guggenheim- Anderson- deBoer (GAB)- model. Both models described the adsorption behaviour well in their range of validity, while only the GAB-model was adequate for describing the desorption behaviour. Hysteresis effect occurred in each adsorption-desorption pair. The isosteric heat of sorption of both substances was determined for adsorption, desorption respectively. Slight differences in the sorption behaviour occurred due to processing, while quality of the gelatine was not affected.
Keywords: $CO_2$ spray drying, gelatine powder, sorption isotherms, isosteric heat of sorption, Guggenheim-Anderson-deBoer model, Brunauer-Emmet-Teller model
Published in DKUM: 10.07.2015; Views: 1887; Downloads: 80
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6. Dynamic property of aluminium foamSeiichi Irie, Toshihiko Okano, Shigeru Tanaka, Matej Vesenjak, Zoran Ren, Kazuyuki Hokamoto, Shigeru Itoh, 2010, published scientific conference contribution abstract Keywords: aluminium foam, powder gun, high strain rate
Published in DKUM: 10.07.2015; Views: 1739; Downloads: 49
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7. Particles formation and particle design using supercritical fluidsŽeljko Knez, Eckhard Weidner, 2003, review article Abstract: Major recent advances. Particle formation and design of solid particles and powdery composites with unique properties is at the moment a major developmentof supercritical fluids (synonymsČ dense gasses, dense fluids, highpressure) applications. This review will focus on recent advances and on fundamentals of these processes and their applications.
Keywords: chemical processing, high pressure technology, micronization, supercritical fluids, micro-particles, nano-particles, powder generation, crystallization, particles from gas saturated solutions
Published in DKUM: 01.06.2012; Views: 3777; Downloads: 110
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8. Multifunctional composites by high-pressure spray processesEckhard Weidner, Marcus Petermann, Željko Knez, 2003, review article Abstract: A series of spraying processes designed to generate powders and composites using supercritical fluids have been proposed in the past 15 years. In this review, thermo- and fluid-dynamic aspects and engineering principles are discussed and advantages of such technologies are demonstrated. These new techniques display convincing advantages, producing competitive high-quality products with tailor-made properties. Initial industrial applications have been achieved in the production of food products and fine-chemicals.
Keywords: chemical processing, high pressure technology, micronization, supercritical fluids, particles, powder generation, thermodynamics, fluid dynamics, PGSS
Published in DKUM: 01.06.2012; Views: 2658; Downloads: 104
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9. Hydroxylammonium fluorogermanatesIrena Ban, Matjaž Kristl, Mihael Drofenik, Arkadije Popović, 2004, original scientific article Abstract: A new hydroxylammonium compound (NH3OH)2GeF6, has been synthesized by the addition of solid NH3OHF to a solution of GeO2 dissolved in 20% HF. The compound was characterized by chemical analysis and X-ray powder diffraction, the thermal decomposition was studied by thermal analysis and mass spectrometry. (NH3OH)2GeF6 crystallizes monoclinic. Two endothermic and two exothermic peaks have been observed on the DSC curve, the decomposition product at 500 °C is GeO2.
Keywords: inorganic chemistry, synthesis, characterisation, hydroxylammonium fluorogermanates, x-ray powder diffraction, mass spectroscopy, thermal analysis
Published in DKUM: 01.06.2012; Views: 3353; Downloads: 113
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10. The development of a new process for gentle drying, micronisation and formulation of a high viscous biopoymerChristian Reibe, 2011, dissertation Abstract: Biopolymers are characterised by their biodegradable behaviour in certain environments. Especially the development of natural biopolymers from renewable resources is gathering increasing interest in the scientific as well as in the industrial sectors . Since Biopolymers may be tailored to specific requirements, the encapsulation of pharmaceutical compounds or flavours in biopolymers would open wide avenues for the production of controlled- release systems. Most common mechanical pulverisation processes are milling and grinding. With these processes it is not possible to produce specific morphologies like foams or hollow spheres, but always splintered edges. Encapsulation is carried out by common precipitation techniques.
Gelatine, as a widely applied biopolymer, represents one example of those substances of large interest, but it is difficult to process. Especially gelatines with high molecular mass are difficult or almost impossible to be pulverized by spray drying techniques, due to their high viscosity.
In the frame of this research work, an integrated high-pressure spraying, drying and pulverization process for high viscous gelatine was developed, based on a combination of the water removing effects "Evaporation" and "Gas-solubility". The resulting products were dry, free-flowing gelatine powders, still exhibiting high molecular masses. Due to the new, gentle method of processing, a completely new gelatine product with unique properties was obtained. Even the encapsulation of edible oil in high ratios was found to be possible with this new process. The characterisation was carried out by standard methods for gelatine on the one hand side, and standard procedures for characterising powders on the other hand side.
The developed process was patented under the identifier "WO 002009135601 A1".
Keywords: High Pressure Process, Supercritical Fluids, High molecular mass Gelatine, Micronisation, CO-2 - spray drying, Encapsulation, Gelatine Powder
Published in DKUM: 26.01.2011; Views: 3525; Downloads: 267
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