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Membranes from polysulfone/N,N-dimethylacetamide/water system
Vladimir Kaiser, Črtomir Stropnik, 2000, izvirni znanstveni članek

Opis: Polymeric membranes were prepared by the wet-phase separation method from solutions of different contents of polysulfone in N,N-dimethylacetamide; solutions were cast in different thickness before immersion into the pure water coagulation bath. Two main processes take place during the formation of membranes: nucleation and growth of the polymer lean phase with subsequent solidification of the polymer rich phase, and the formation of channels, macrovoids and mega-macrovoids. By the first process a cellular structure is formed whilst the second process connects the cells by opening the space between them. The degree of interconnectedness is an additional factor that affects the pure water flux. By changing the cast solution compositions and/or their cast thickness the interconnectedness of the cells can be controlled.
Ključne besede: chemical technology, organic technology, polymer membranes, membrane preparation, wet phase inversion, polymers, polysulphon
Objavljeno: 18.08.2017; Ogledov: 4; Prenosov: 0
.pdf Polno besedilo (112,47 KB)

Mednarodni standardi veličine in enote
Peter Glavič, 2003, strokovni članek

Opis: V prispevku so predstavljeni mednarodni standardi ISO 31 (Veličine in enote) z naslednjimi deli: ISO 31-0 (Splošna načela), ISO 31-1 (Prostor in čas), ISO 31-2 (Periodični in sorodni pojavi), ISO 31-3 (Mehanika), ISO 31-4 (Toplota), ISO 31-5 (Elektrika in magnetizem), ISO 31-8 (Fizikalna kemija in molekulska fizika), ISO 31- 12 (Karakteristična števila) in drugimi. Poudarek je na splošnih načelih, ki so pomembna za pisanje poročil, referatov, člankov, knjig in za pedagoški proces.
Ključne besede: metrologija, mednarodni standardi ISO 31, simboli, veličine, enote, mednarodni sistem enot (SI), prostor, čas, periodični pojavi, mehanika, toplota, elektrika, magnetizem, fizikalna kemija, molekulska fizika, karakteristična števila
Objavljeno: 18.08.2017; Ogledov: 3; Prenosov: 0
.pdf Polno besedilo (210,40 KB)

High-resolution X-ray absorption spectrometry of atomic vapors
Andrej Mihelič, Alojz Kodre, Iztok Arčon, Jana Padežnik Gomilšek, 2004, izvirni znanstveni članek

Opis: A measurement of an x-ray absorption spectrum of a monatomic sample yields pure atomic absorption essential for the EXAFS (Extended X-ray Absorption Fine Structure) analysis in cases of a weak structural signal. A construction of an absorption cell to contain vapor sample takes into account specific properties of the investigated element. Metal-vapor absorption cells for the elements K, Zn, Rb, Cd, Cs, and Hg are presented and comments are made on the use of materials and the operating mechanisms of the cells.
Ključne besede: x-ray absorption, atomic vapors, K, Zn, Rb, Cd, Cs, EXAFS
Objavljeno: 18.08.2017; Ogledov: 4; Prenosov: 0
.pdf Polno besedilo (105,40 KB)

High resolution melting curve analysis for high-throughput SNP genotyping in IL23R gene and association of IL23R with Slovenian inflammatory bowel diseases patients
Mitja Mitrovič, Uroš Potočnik, 2010, izvirni znanstveni članek

Opis: Single nucleotide polymorphism (SNP) analysis is important tool in the studies of genetic factors associated with complex diseases and with genetically influenced response to drug therapy (pharmacogenetics). Recently, a new generation of generic dsDNA binding dyes (LCGreen$^{TM}$) contributed to the development of fast and low-cost method for SNP detection and/or genotyping based on high resolution melting (HRM) analysis. The aim of our study was to develop HRM assay for IL23R gene (rs7517847) and to perform association study in Slovenian inflammatory bowel diseases (IBD) patients. We genotyped 345 Slovenian healthy controls and 295 IBD patients including 159 with Crohn's disease (CD) and 136 with ulcerative colitis (UC) for rs7517847 polymorphism in IL23R gene using standard RFLP and optimized HRM methods. In this study, we showed, that HRM is a simple, fast and reliable method for genotyping of clinical samples where homozygotes (GG and TT) were determined by Tm calling method and difference between homozygotes and heterozygotes was determined by different melting curve shape using gene scanning method. With combination of results from Tm calling and gene scanning methods, we achieved 98,6% concordance between PCR-RFLP and PCRHRM results, based on the analysis of 640 samples. We found statistically significant association of IL23R polymorphism with Slovenian Crohn's disease patients when comparing genotype and allele frequencies between CD patients and controls. Allele frequency of minor allele G was 0,46 in controls and was reduced to 0,33 in CD patients (p < 0,001, OR = 0,588). The frequency of T/T genotype carriers was higher in CD patients (50,3%) than in controls (26,7%, p = 0,002, OR = 2,558). We found weak association between IL23R polymorphism and Slovenian UC patients. Carriers of T/T genotype have higher risk for UC (p = 0,035, OR = 1,599). These results suggest IL23R plays important role in CD and UC development in Slovenian patients.
Ključne besede: SNP genotyping, high resolution melting, DNA dyes, inflammatory bowel diseases, LC Green Plus
Objavljeno: 18.08.2017; Ogledov: 2; Prenosov: 0
.pdf Polno besedilo (232,19 KB)

Forward osmosis in wastewater treatment processes
Jasmina Korenak, Subhankar Basu, Malini Balakrishnan, Claus Hélix-Nielsen, Irena Petrinić, 2017, izvirni znanstveni članek

Opis: In recent years, membrane technology has been widely used in wastewater treatment and water purification. Membrane technology is simple to operate and produces very high quality water for human consumption and industrial purposes. One of the promising technologies for water and wastewater treatment is the application of forward osmosis. Essentially, forward osmosis is a process in which water is driven through a semipermeable membrane from a feed solution to a draw solution due to the osmotic pressure gradient across the membrane. The immediate advantage over existing pressure driven membrane technologies is that the forward osmosis process per se eliminates the need for operation with high hydraulic pressure and forward osmosis has low fouling tendency. Hence, it provides an opportunity for saving energy and membrane replacement cost. However, there are many limitations that still need to be addressed. Here we briefly review some of the applications within water purification and new developments in forward osmosis membrane fabrication.
Ključne besede: wastewater treatment, biomimetic membranes, desalination, draw solutions, forward osmosis
Objavljeno: 18.08.2017; Ogledov: 3; Prenosov: 0
.pdf Polno besedilo (403,57 KB)

EXAFS and IR analysis of electrochromic $NiO_x$/$NiO_xH_y$ thin films
Jana Padežnik Gomilšek, Romana Cerc Korošec, Peter Bukovec, Alojz Kodre, 2008, izvirni znanstveni članek

Opis: Electrochromic (EC) thin films of $NiO_x$ and $NiO_xH_y$ are prepared by sol-gel method from nickel chloride precursor and deposited onto a suitable substrate by dip-coating technique. The development of the structure with thermal treatment is investigated by EXAFS and IR spectroscopy in two series of films, with high and low concentration of chloride as counter ions. In the former, the predominant structure before thermal treatment is nickel hydroxide. The baking induces condensation, yet with no trace of NiO. In the latter group, colloidal particles are indicated, on which acetate groups are adsorbed or coordinated. At the maximum EC-response the formation of NiO grains is established by EXAFS and IR.
Ključne besede: electrochromism, thin films, nickel oxide, nickel hydroxide, EXAFS
Objavljeno: 18.08.2017; Ogledov: 3; Prenosov: 0
.pdf Polno besedilo (286,00 KB)

Effects of translational and rotational degrees of freedom on the hydration of ionic solutes as seen by the popular water models
Tomaž Mohorič, Urban Bren, Vojko Vlachy, 2015, izvirni znanstveni članek

Opis: We employed molecular dynamics simulations with separate thermostats for translational and rotational temperatures in order to study the effects of these degrees of freedom on the hydration of ions. In this work we examine how water models, differing in charge distribution, respond to the rise of rotational temperature. The study shows that, with respect to the distribution of negative charge, popular water models lead to different responses upon an increase of the rotational temperature. The differences arise in hydration of cations, as the negative charge distribution on the model solvent represents the determining factor in such cases. The cation-water correlation increases with the increasing rotational temperature if negative charge is placed in (or close to) the centre of the water molecule (a typical example is the SPC water model) and decreases, when the negative charge is shifted from the centre (as in the TIP5P model of water). Because all the water models examined here have similar distributions of positive charge, they all exhibit similar trends in solvation of anions. In contrast to above, the effect of translational temperature variation is similar for all water-solute pairs; any increase in translational temperature decreases the solute-water correlations.
Ključne besede: ionic hydration, water models, degrees of freedom, molecular dynamics
Objavljeno: 18.08.2017; Ogledov: 8; Prenosov: 0
.pdf Polno besedilo (494,01 KB)

Effect of solid state fermentation medium optimization on Pleurotus ostreatus laccase production
Nataša Belšak, Andrej Gregori, Maja Leitgeb, Dušan Klinar, Štefan Čelan, 2015, izvirni znanstveni članek

Opis: The objective of this work was to increase laccase production by Pleurotus ostreatus PLAB through culture medium optimization using solid-state culture conditions. Increased laccase activity was obtained through the design of experiments (DOE) using the Taguchi orthogonal array (OA). Seven factors, viz. lignocellulose, glucose, yeast extract, peptone, $KH_2PO_4$, $MgSO_4$ · $7H_2O$ and $MnSO_4$ · $H_2O$ at three levels and pH at two levels with OA layout of L18 ($2^1 × 3^7$) were selected for the proposed experimental design using Minitab 17 software. Data analysis showed that lignocellulose (20%) and glucose (10 g $L^{–1}$) had a positive effect, whereas $KH_2PO_4$, $MgSO_4$ · $7H_2O$ and $MnSO_4$ · $H_2O$ did not have a significant effect on laccase production. Taguchi OA analysis showed that pH 6, lignocellulose 20%, glucose 10 g $L^{–1}$, yeast extract 6 g $L^{–1}$, peptone 15 g $L^{–1}$, $KH_2PO_4$ 3 g $L^{–1}$, $MgSO_4$ · $7H_2O$ 0.5 g $L^{–1}$ and $MnSO_4$ · $H_2O$ 0.1 g $L^{–1}$ were the optimal conditions to maximize laccase production. The model predicted a 30.37 U $g^{–1}$ dry wt., which agreed with the experimentally obtained laccase activity 29.15 U $g^{–1}$ dry wt. at optimal conditions.
Ključne besede: Taguchi method (DOE), orthogonal array, optimization, Pleurotus ostreatus, laccase production, solid state fermentation
Objavljeno: 18.08.2017; Ogledov: 15; Prenosov: 0
.pdf Polno besedilo (126,99 KB)

Effect of drying parameters on physiochemical and sensory properties of fruit powders processed by PGSS-, vacuum- and spray-drying
Urban Feguš, Uroš Žigon, Marcus Petermann, Željko Knez, 2015, izvirni znanstveni članek

Opis: Aim of this experimental work was to investigate the possibility of producing fruit powders without employing drying aid and to investigate the effect of drying temperature on the final powder characteristics. Raw fruit materials (banana puree, strawberry puree and blueberry concentrate) were processed using three different drying techniques each opera- ting at different temperature conditions: vacuum-drying (–27–17 °C), spray-drying (130–160 °C) and PGSS-drying (112–152 °C). Moisture content, total colour difference, antioxidant activity and sensory characteristics of the proces- sed fruit powders were analysed. The results obtained from the experimental work indicate that investigated fruit pow- ders without or with minimal addition of maltodextrin can be produced. Additionally, it was observed that an increase in process temperature results in a higher loss of colour, reduced antioxidant activity and intensity of the flavour profile.
Ključne besede: particles from gas saturated solutions drying, vacuum-drying, spray-drying, sensory evaluation, fruit powders
Objavljeno: 18.08.2017; Ogledov: 8; Prenosov: 0
.pdf Polno besedilo (249,24 KB)

Distribution of zinc in vineyard areas treated with zinc containing phytopharmaceuticals
Vesna Bukovac, Danimir Kerin, 2000, izvirni znanstveni članek

Opis: Zinc concentration in vineyard soil is, in general, increased markedly by the long term application of zinc containing fungicides. The most significant source of Zn are nowadays dithiocarbamate based fungicides, e.g. Antracol. The concentration of total zinc and EDTA and ammonium lactate (AL) extractable Zn in soils are evaluated together with the concentration of Zn in different inorganic fertilizers and in fungicides. the results of the study indicate in the observed vineyard areas a long term accumulation of zinc appears. The study was made in vineyards of Kalvarija and Meranovo (Maribor, Slovenia).
Ključne besede: zinc, dithiocarbamate, soil
Objavljeno: 18.08.2017; Ogledov: 3; Prenosov: 0
.pdf Polno besedilo (108,83 KB)

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