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Inhibition properties of TRITON-X-100 on ferritic stainless steel in sulphuricacid at increasing temperature
Regina Fuchs-Godec, Gregor Žerjav, 2009, original scientific article

Abstract: The inhibiting action of a non-ionic surfactant of the TRITON-X series (TRITON-X-100) on stainless steel type X4Cr13 in 1.0 M H2SO4 solution at five different temperatures was investigated by the potentiodynamic polarisation measurements. The inhibition efficiency has been calculated in the presence and in the absence of the inhibitor. The experimental data suggest that the inhibition efficiency increases with increasing concentration of the TRITON-X-100, and decreases with the increasing temperature. Adsorption of the non-ionic surfactant used here obeys the Flory- Huggins isotherm. The thermodynamic parameters, such as, the heat of adsorption, adsorption entropy, and the adsorption free energy, have been calculated by employing thermodynamic equations. Kinetic parameters, also been evaluated.
Keywords: non-ionic surfactants, corrosion inhibitors, sulphuric acid, Flory-Huggins adsorption isotherm
Published: 31.05.2012; Views: 1025; Downloads: 39
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Sandi Majninger, 2015, undergraduate thesis

Abstract: V diplomskem delu smo raziskali možnosti uporabe spletnih tehnologij za razvoj mobilnih aplikacij. Preučili smo razlike med načinom interakcije na namiznih računalnikih in napravah z na dotik občutljivimi zasloni. Opisali smo, kako so se uporabniški vmesniki aplikacij prilagodili na nov način interakcije. Poiskali smo nabor orodij, ki omogočajo uporabo spletnih tehnologij za razvoj mobilnih aplikacij. Izbrali smo programsko ogrodje Ionic in z njim razvili hibridno mobilno aplikacijo, ki omogoča pregled, iskanje, brskanje in shranjevanje elektronskih gradiv z spletnega portala Digitalne knjižnice Univerze v Mariboru.
Keywords: Ionic, mobilna aplikacija, spletne tehnologije, Cordova, Javascript
Published: 13.10.2015; Views: 859; Downloads: 125
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Enzyme-catalyzed acylation of (R,S)-1-phenylethanol in 1-butyl-3-methylimidazolium based ionic liquids
Muzafera Paljevac, Željko Knez, Maja Leitgeb, 2009, original scientific article

Abstract: Ionic liquids represent an exciting new class of reaction solvents for catalysis, which have been used successfully for enzyme-catalyzed reactions. In present research, three different ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl)] amide, were synthesized. They were used as a reaction medium for enzyme-catalyzed acylation of (R,S)-1- phenylethanol with vinyl acetate. Mentioned enzymatic reaction was performed in a batch stirred-tank reactor in order to optimise different reaction parameters (biocatalyst concentration, temperature, ...). The influence of three different immobilized lipases on reaction performance was studied as well. The highest reaction rate and conversion of 49.7% after 5 h of reaction performance was achieved in the case when immobilized lipase Novozym 435 from Candida antarctica was used as a biocatalyst and hydrophilic ionic liquid 1-butyl- 3-methylimidazolium tetrafluoroborate as a solvent. Therefore, the optimization of different reaction parameters on lipase- catalyzed acylation of (R,S)-1-phenylethanol was carried out in 1-butyl-3-methylimidazolium tetrafluoroborate.
Keywords: immobilized lipase, acylation, (R, S)-1-phenylethanol, ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate
Published: 31.05.2012; Views: 1096; Downloads: 15
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Lipase-catalyzed transesterification of (R,S)-1-phenylethanol in SC $CO_2$ and in SC $CO_2$/ionic liquid systems
Muzafera Paljevac, Željko Knez, Maja Leitgeb, 2009, original scientific article

Abstract: Commercial immobilized lipase B from Candida antarctica (CALB) was successfully applied to catalyzing the transesterification of (R,S)-1-phenylethanol in supercritical carbon dioxide and in supercritical carbon dioxide/ionic liquid biphasic system. Firstly, the variables affecting the performance of CALB in transesterification reactions in supercritical carbon dioxide, such as CALB concentration, temperature and pressure, were studied. An increase in the conversion and in the reaction rate was observed as the CALB/substrate ratio, temperature and pressure, were increased from 4.3 to 19.9, from 40 °C to 80 °C and from 8 MPa to 10 MPa, respectively. Further increase in temperature from 80 °C to 120 °C and pressure from 10 MPa to 30 MPa resulted in lower conversion and lower initial reaction rate. Furthermore, different vinyl esters were used as acyl donors for CALB-catalyzed transesterification of (R,S)-1-phenylethanol in supercritical carbon dioxide. The highest initial reaction rate was attained with vinyl butyrate, although 50% conversion was attained faster when vinyl acetate was used as acyl donor. Secondly, in transesterification of (R,S)-1-phenylethanol, performed in supercritical carbon dioxide/ionic liquid biphasic system, influence of concentration of 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF$_4$] was studied. The addition of 50 mmol (70% w/w reaction mixture) of [bmim][BF$_4$] to the reaction system gave the best result in terms of transesterification rate.
Keywords: candida antarctica lipase B, transesterification, (R, S)-1-phenylethanol, ionic liquids, vinyl acetate, supercritical carbon dioxide
Published: 31.05.2012; Views: 1303; Downloads: 32
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Rheological study of interactions between non-ionic surfactants and polysaccharide thickeners used in textile printing
Rebeka Fijan, Sonja Šostar-Turk, Romano Lapasin, 2007, original scientific article

Abstract: The influence of four non-ionic surfactants (isododecyl and cetyl polyoxyethylene ethers) on aqueous polysaccharide solutions (sodium alginate, guar gum, and sodium carboxymethyl guar), applicable for textile printing pastes, were studied via rheological measurements. Rheology of polysaccharide-surfactant solutions in aqueous matrices is primarily governed by polymer content, which imparts marked shear-thinning and viscoelastic character to the system. Such properties are modulated in moderate but sensible way by changes in surfactant concentration or type. Above 3% surfactants addition to non-substituted guar gum solutions results in a significant impact leading to phase separation and a particular strongly associated phase is formed due to hydrogen bonds between ethylene oxy units from the surfactant and primary hydroxyl groups in guar. A satisfactory fitting of viscosity data is obtained with both the Cross equation and the Roberts-Barnes-Carew model. The experimental results of mechanical spectra can be described quite satisfactory with both the Friedrich-Braun and the generalized Maxwell models.
Keywords: textile printing, polysaccharide thickeners, rheology, non-ionic surfactant, polymer-surfactant interactions, viscoelasticity
Published: 01.06.2012; Views: 927; Downloads: 29
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Inhibitory effect of non-ionic surfactants of the TRITON-X series on the corrosion of carbon steel in sulphuric acid
Regina Fuchs-Godec, 2007, original scientific article

Abstract: The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 and TRITON-X-405, on stainless steel (SS) type X4Cr13 in sulphuric acid were investigated by potentiodynamic polarisation measurements. It was found that these surfactants act as good inhibitors of the corrosion of stainless steel in 2 mol L-1 H2SO4 solution, but the inhibition efficiency strongly depends on the electrode potential. Thepolarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors and adsorb on the stainless steel surface, in agreement with the Flory-Huggins adsorption isotherm. Calculated Gads values are -57.79 kJ mol-1 for TRITON-X-100, and -87.5 kJ mol-1 for TRITON-X-405. From the molecular structure it can be supposed that these surfactants adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group, suggesting a chemisorption mechanism.
Keywords: electrochemistry, corrosion inhibitors, non-ionic surfactants, Flory-Huggins isotherm, critical micelle concentration, sulphuric acid
Published: 01.06.2012; Views: 994; Downloads: 39
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Enzymatic esterification of glycerol and stearic acid in non-conventional media
Zsófia Csanádi, Katalin Bélafi-Bakó, Eszter Szentgyörgyi, László Gubicza, Željko Knez, Maja Leitgeb, 2010, original scientific article

Abstract: Ionic liquids as trihexyl-tetradecyl-phophonium-dicyanamide (Cyphos 105) and cocosalkyl-pentaethoxi-methyl-ammonium-methosulfate (Ammoeng 100) were applied for the esterification of stearic acid and glycerol using Candida antarctica lipase (Novozyme 435). When only ILs were applied as solvents at 1:15 initial substrate molar ratio the conversion was 76 and 78 % in the case of two kinds of ILs, respectively. Mixed the ILs and supercritical $CO_2$ the conversion reached 79 and 86 %. The conversion was found highest in supercritical $CO_2$, reached 90 %. Moreover formation of glycerol-di-stearate is much lower in the case of ILs comparing with $SCCO_2$.
Keywords: glycerol-mono-stearate, Lipase, ionic liquids, supercritical $CO_2$, carbon dioxide
Published: 10.07.2015; Views: 387; Downloads: 40
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Matija Šarabon, 2015, bachelor thesis/paper

Abstract: Pri čebelarjenju z več čebeljimi družinami ne moremo vseh sprememb, ki nastanejo v panjih, shranjevati v lasten spomin. Za uspešno premagovanje problemov, ki pri tem nastanejo, nujno potrebujemo sistem beleženja podatkov. Beleženje podatkov na list papirja je zamudno, podatki so razpršeni, pregled zbranih podatkov pa nepregleden. Razvoj prototipa rešitve smo zasnovali v orodju Balsamiq Mockups ter ga izdelali s pomočjo AngularJS in Ionica. Struktura Ionica služi kot izgled aplikacije, samo funkcionalnost pa mu doda AngularJS ter baza podatkov Firebase, kamor aplikacija shranjuje vnesene podatke. Prednost aplikacije je njena preprosta uporaba, podatki so zbrani na enem samem mestu, njihov pregled pa je enostaven. Prototip razvite aplikacije smo razvijali za tablične računalnike s pred-nameščenim operacijskim sistemom Andorid ali iOS. Aplikacijo je namenjena uporabi čebelarjem, ki si želijo preprostega vnašanja podatkov pridobljenih z opazovanjem čebeljih družin.
Keywords: čebelarstvo beleženje podatkov node.js angular.js Ionic Framwork Baze podatkov
Published: 16.09.2015; Views: 491; Downloads: 91
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High bulk modulus of ionic liquid and effects on performance of hydraulic system
Milan Kambič, Roland Kalb, Tadej Tašner, Darko Lovrec, 2014, original scientific article

Abstract: Over recent years ionic liquids have gained in importance, causing a growing number of scientists and engineers to investigate possible applications for these liquids because of their unique physical and chemical properties. Their outstanding advantages such as nonflammable liquid within a broad liquid range, high thermal, mechanical, and chemical stabilities, low solubility for gases, attractive tribological properties (lubrication), and very low compressibility, and so forth, make them more interesting for applications in mechanical engineering, offering great potential for new innovative processes, and also as a novel hydraulic fluid. This paper focuses on the outstanding compressibility properties of ionic liquid EMIM-EtSO4, a very important physical chemically property when IL is used as a hydraulic fluid. This very low compressibility (respectively, very high Bulk modulus), compared to the classical hydraulic mineral oils or the non-flammable HFDU type of hydraulic fluids, opens up new possibilities regarding its usage within hydraulic systems with increased dynamics, respectively, systemsʼ dynamic responses.
Keywords: ionic liquids, hydraulic system, high bulk modulus
Published: 15.06.2017; Views: 196; Downloads: 66
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Klemen Žnidar, 2016, master's thesis/paper

Abstract: V tem delu želimo raziskati in predstaviti razvoj prototipa mobilne hibridne aplikacije za prikaz vremena. Osredotočeni smo na razvoj in potek razvoja mobilne hibridne aplikacije od snovanja do zaključka. Mobilna hibridna aplikacija je zgrajena na platformi Apache Cordova in ogrodju Ionic, ki združuje mobilnemu svetu prirojene tehnologije, kot so CSS3, HTML5, SaaS, AngularJS in druge aktualne tehnologije v svetu mobilnih aplikacij. Za mobilno hibridno aplikacijo smo se odločili zato, da jo lahko poganjamo na različnih platformah in nismo omejeni le na določen operacijski sistem. Prototip mobilne hibridne aplikacije lahko razvijemo hitreje kot primerljiv prototip izvorne aplikacije. Cordova nam ponuja vtičnike, s katerimi dodelujemo aplikacije. S tem dosežemo manjše stroške, kar je v trenutnih časih pomembno. AngularJS nam omogoča dobro sprotno testiranje in posledično odkrivanje potencialnih napak že zgodaj v razvoju. Zaradi uspešnosti prinašanja rezultatov in skrajšanja časa razvoja smo izbrali agilne metodologije razvoja programske opreme.
Keywords: hibridna aplikacija ogrodje Ionic orodje AngularJS Cordova OpenWeatherMap
Published: 17.11.2016; Views: 538; Downloads: 89
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