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1.
Uporaba kremenove mikrotehtnice za spremljanje adsorpcije biopolimerov
Aleš Doliška, 2011, original scientific article

Abstract: Uporaba polimerov naravnega izvora oziroma biopolimerov se v zadnjih letih povečuje, posebno na področju biorafinerije. Najobetavnejši biopolimeri so rastlinski polisaharidi, ki so potencialni materiali tudi za hidrokoloide in nove napredne naravne materiale. Velika količina potencialno uporabnih hemiceluloz se zavrže med proizvodnjo termomehanične pulpe (TMP) z odpadnimi procesnimi vodami. Hemiceluloze iz mehkega lesa, kot je smrekovina, so bile testirane kot material za proizvodnjo biorazgradljivih filmov in hidrokoloidov. Adsorpcija in stabilnost teh adsorbiranih hemiceluloznih filmov sta pomembna dejavnika v koloidni in prehranski kemiji. Ena od tehnik, s katerimi lahko spremljamo adsorpcijo v realnem času, je kremenova mikrotehtnica (QCM-D). V našem prispevku smo uporabili kremenovo mikrotehtnico za adsorpcijo hemiceluloz iz smrekovine na modelno površino polietilentereftalata (PET). Dodana sol je povečala stopnjo adsorpcije hemiceluloz na površino PET zaradi omiljenja odbojnih sil med negativno nabito površino PET in negativnimi skupinami v hemicelulozah.
Keywords: kremenova mikrotehtnica, hemiceluloze, termomehanična pulpa, galaktoglukomanan
Published: 01.09.2017; Views: 670; Downloads: 93
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2.
Hidroliza reaktivnih barvil pri barvanju lanu v odvisnosti od vrste procesa
Darinka Fakin, Alenka Ojstršek, Aleš Doliška, 2007, original scientific article

Abstract: Lanena vlakna (Linum ussitatissimum) spadajo v skupino naravnih celuloznih vlaken, njihova kakovost pa je odvisna od sorte lanu, postopkov ločevanja vlaken od drugih delov stebla, predobdelave, barvanja in postopkov plemenitenja. Kadar laneni izdelki zahtevajo vrhunske obstojnosti, uporabljamo za barvanje reaktivna barvila, ki jih odlikujejo razmeroma enostaven postopek barvanja, briljantni barvni toni ter zaradi nastanka kovalentnih vezi med vlaknom in barvilom tudi dobre mokre obstojnosti. Postopki predobdelave in beljenja lanenih vlaken vplivajo zaradi razgradnje primesi na hidrofilnost, hkrati pa tudi na fizikalno- kemijske in barvalne lastnosti vlaken. Kinetične in termodinamične zakonitosti procesa barvanja le-teh so odvisne tudi od kemijske strukture barvil, različnih tehnoloških postopkov in parametrov barvanja. Pogosto težavo pri barvanju z reaktivnimi barvili predstavlja močna obarvanost odpadnih barvalnih kopeli, kar je predvsem posledica hidrolize reaktivnih barvil med procesom barvanja. Zato smo se v raziskavi osredotočili na vpliv postopka barvanja (izčrpavanje in impregnacija) in reaktivnega sistema barvil na hidrolizo reaktivnih barvil pri barvanju lanene tkanine. Iz rezultatov dela izhaja, da je količina hidroliziranih in nevezanih barvil odvisna od vrste barvila, njegove kemijske strukture, velik pomen pa ima tudi primeren izbor postopka barvanja.
Keywords: lan, barvanje lanu, vinilsulfonska reaktivna barvila, bireaktivna barvila, hidroliza, spektroskopija, barvna metrika
Published: 31.08.2017; Views: 428; Downloads: 75
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3.
Chemical modification and characterization of poly(ethylene terephthalate) surfaces for collagen immobilization
Mioara Drobota, Zdenka Peršin, Lidija Fras Zemljič, Tamilselvan Mohan, Karin Stana-Kleinschek, Aleš Doliška, Matej Bračič, Volker Ribitsch, Valeria Harabagiu, Sergiu Coseri, 2013, original scientific article

Abstract: The functionalization of poly(ethylene terephthalate) (PET) surface films by reactions with multifunctional amines such as triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) was investigated. For the functionalization of PET films surface we used a new way of treatment, a 'sandwich model'. Physical-chemical properties of functionalized PET films were analysed. Qualitative and quantitative determination of the introduced amine groups were examined by means of Fourier Transform Infrared Attenuated Total Reflexion(FTIR - ATR), X-ray photoelectron spectroscopy (XPS), and potentiometric titration. Gained wetting properties were determined by using contact angle measurements and thoroughly analysed by acid-base approach. In addition, surface topography was investigated by atomic force microscopy (AFM). The amount of the introduced amino groups after TETA incorporation has been found to be two times higher as compared to TEPA. Wetting properties were significantly improved after aminolysis. Surface free energy was higher for PET - TETA treated film than that observed for PET - TEPA treated which is in accordance with titration results. The collagen immobilization onto PET treated films was evidenced by using AFM and subsequently by using XPS.
Keywords: PET, aminolysis, AFM, collagen immobilization
Published: 03.04.2017; Views: 770; Downloads: 342
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4.
Modification of PET-polymer surface by nitrogen plasma
Rok Zaplotnik, Metod Kolar, Aleš Doliška, Karin Stana-Kleinschek, 2011, original scientific article

Abstract: Low pressure weakly nitrogen plasma was applied for incorporation of nitrogen-containing functional groups onto poly(ethylene terephthalate) - PET polymer. Nitrogen plasma was created in an electrode-less radiofrequency discharge at the nominal power of 200 W and the frequency of 27.12 MHz. Nitrogen molecules entered the discharge region were highly excited, partially dissociated and weakly ionized. Transformation into the state of plasma allowed for creation of chemically reactive particles with a high potential energy while the kinetic energy remained close to the value typical for room temperature. The chemical reactivity allowed for rapid functionalization with nitrogen-rich functional groups. The appearance of these groups was monitored by X-ray photoelectron spectroscopy - XPS. The polymer surface was quickly saturated with nitrogen indicating that the modification was limited to an extremely thin surface film.
Keywords: poly(ethylene terephthalate), nitrogen plasma, surface modification, functional groups, X-ray photoelectron spectroscopy
Published: 17.03.2017; Views: 538; Downloads: 79
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6.
Application and characterization of microstructured cellulose thin films
Rupert Kargl, Tamilselvan Mohan, Aleš Doliška, Karin Stana-Kleinschek, Volker Ribitsch, 2013, published scientific conference contribution

Keywords: celuloza
Published: 10.07.2015; Views: 1030; Downloads: 8
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Decolorization of textile dyes by whole cultures of Ischnoderma Resinosum and by purified laccase and Mn-peroxidase
Vanja Kokol, Aleš Doliška, Ivana Eichlerová, Petr Baldrian, František Nerud, 2007, original scientific article

Abstract: Ischnoderma resinosum produced extracellular ligninolytic enzymes laccase and MnP. The activity of laccase achieved the maximum on day 10 (29.4 U L-1), the MnP on day 14 (34.5 U L-1). Laccase and Mn-peroxidase were purified from the culture liquid using gel permeation and ion-exchange chromatographies. Purified Mn-peroxidase performed decolorization of all textile dyes tested (Reactive Black 5, Reactive Blue 19, Reactive Red 22 and Reactive Yellow 15). Laccase was inactive with Reactive Black 5 and Reactive Red 22, while all dyes were decolorized after addition of the redox mediators violuric acid (VA) and hydroxybenzotriazole (HBT). The culture liquid from I. resinosum cultures was also able to decolorize all dyes as well as the synthetic dyebaths in the presence of VA and HBT. The highest decolorization rates were detected in acidic pH (3-4).
Keywords: Ischnoderma resinosum, Basidiomycetes, Laccase, Mn-peroxidase, Textile dyes, ligninolytic enzymes
Published: 01.06.2012; Views: 1202; Downloads: 69
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10.
Tuning of poly(ethylene terephtalate)(PET)surface properties by oxygen plasma treatment
Aleš Doliška, Metod Kolar, 2011, original scientific article

Abstract: Modification of surface properties of poly(ethyleneterephtalate) (PET) thin films by treatment with weakly ionized oxygen plasma was studied by contact angles of water and diiodomethane (DIM) drops. Samples were exposed to oxygen plasma with the ion density of 5 x 1015/m[sup]3 and the neutral oxygen atom density of 3 x 1021/m[sup]3. Just after the treatment they were characterized by contact angle measurements. Results showed a quick decrease of the water contact angle in the first few seconds of plasma treatment, while prolonged treatment did not cause any substantiated modification. The contact angles of DIM, on the other hand, remained rather constant for the first several secondsof plasma treatment, and increased after prolonged treatment. It was found that the dispersion component of the surface free energy decreased with increasing treatment time, while the polar component increased with treatment time. The results were explained by surface functionalization as well as by roughness effects.
Keywords: poly(ethylene terephtalante), PET, oxygen plasma, contact angle, hydrophilic, functionalization
Published: 01.06.2012; Views: 1431; Downloads: 43
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