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1.
Funkcionalizacija vlaken s sinergistično formulacijo tenzid-polisaharid
Matej Bračič, 2011, magistrsko delo/naloga

Opis: Številni postopki funkcionalizacije medicinskih tekstilij so človeku in okolju neprijazni. Zaradi tega, vse večje zdravstvene osveščenosti ljudi in številnega porasta različnih bolezni se povečuje zanimanje za postopke, kjer se uporabljajo okolju prijazni alternativni polisaharidi. Večina alternativnih polisaharidov ima za tovrstno uporabo pomanjkljivosti, kot je omejena inhibicija patogenih bakterij. Ideja magistrske naloge je v razvoju sinergistične formulacije med polisaharidom hialuronsko kislino z vlažilnim učinkom in novo, naravno kationsko površinsko aktivno snovjo MKM s protimikrobnimi lastnostmi, za premaz na viskozni tkanini. Za karakterizacijo sinergistične formulacije med MKM in hialuronsko kislino smo uporabili nevtralizacijske potenciometrične titracije, potenciometrične titracije z uporabo ionselektivne elektrode, občutljive za površinsko aktivne snovi, ter fluorimetrične titracije na osnovi pirena. Rezultati so pokazali, da so interakcije med obema nad kritično koncentracijo asociacije močno kooperativnega značaja. Izoterme stopnje vezanja pa kažejo na vezavo površinsko aktivnega sredstva na hialuronsko kislino v presežku. Karakterizacijo viskozne tkanine, funkcionalizirane s sinergistično formulacijo, smo izvedli z uporabo nevtralizacijskih potenciometričnih titracij, meritvijo stičnega kota s tenziometrijo in protimikrobnim testiranjem. Funkcionalizirana viskozna tkanina izkazuje pozitiven naboj zaradi prisotnosti MKM, kar se neposredno odraža v njeni izredni redukciji patogenih bakterij. Funkcionalizacija viskozne tkanine s sinergistično formulacijo med MKM in hialuronsko kislino je inovativna in primerna za uporabo v medicinske namene, predvsem na področju celjenja ran.
Ključne besede: medicinske tekstilije, viskoza, površinsko aktivne snovi, polisaharidi, hialuronska kislina, potenciometrične titracije, fluorimetrična spektroskopija, tenziometrija, stični kot, protimikrobno testiranje
Objavljeno: 12.10.2011; Ogledov: 1721; Prenosov: 214
.pdf Polno besedilo (1,48 MB)

2.
Uporaba hitozana na tekstilijah za medicinske namene
Tijana Ristić, Matej Bračič, Andrej Zabret, Lidija Fras, 2011, objavljeni znanstveni prispevek na konferenci

Opis: Hitozan je kationski biopolimer, pridobljen iz polisaharida hitina. Zaradi svojih izjemnih lastnosti, kot so biorazgradljivost, netoksičnost in protimikrobna učinkovitost je hitozan našel uporabnost na različnih področjih, predvsem v farmaciji, medicini in tekstilni industriji. V zadnjem času je mogoče opaziti porast zanimanja za uporabo hitozana v medicinskih in higienskih aplikacijah, v obliki vlaken, membran, hidrogelov, ali kot premaz za doseganje protimikrobnih lastnosti tekstilij.
Ključne besede: hitozan, medicinske tekstilije, protimikrobni učinek
Objavljeno: 01.06.2012; Ogledov: 1119; Prenosov: 60
URL Polno besedilo (0,00 KB)

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Chemical modification and characterization of poly(ethylene terephthalate) surfaces for collagen immobilization
Mioara Drobota, Zdenka Peršin, Lidija Fras, Tamilselvan Mohan, Karin Stana-Kleinschek, Aleš Doliška, Matej Bračič, Volker Ribitsch, Valeria Harabagiu, Sergiu Coseri, 2013, izvirni znanstveni članek

Opis: 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.
Ključne besede: PET, aminolysis, AFM, collagen immobilization
Objavljeno: 03.04.2017; Ogledov: 105; Prenosov: 1
.pdf Polno besedilo (2,48 MB)

5.
ANALIZA IGRE SLOVENSKE MOŠKE MLADINSKE REPREZENTANCE V EGIPTU 2009
Matej Bračič, 2016, diplomsko delo

Opis: Predmet diplomskega dela je bila analiza igre slovenske moške mladinske rokometne reprezentance na svetovnem prvenstvu v Egiptu 2009. Namen dela je bil na osnovi kvantitativnih in kvalitativnih podatkov o igri naše mladinske reprezentance na izbranih tekmah podati smernice za nadaljnji razvoj modela rokometne igre slovenskih moških reprezentanc v mlajših starostnih kategorijah. Želeli smo tudi prispevati k razjasnitvi dejstva, da so slovenske reprezentančne selekcije dokaj uspešne v mlajših starostnih in manj, ko se približujejo absolutni kategoriji. Vzorec merjenk predstavljajo igralci slovenske moške mladinske reprezentance, ki so nastopili na SP 2009 v Egiptu. V vzorcu spremenljivk smo zajeli tehnično taktične aktivnosti, ki so uveljavljene za spremljanje modela igre v sodobnem rokometu. Statistične podatke o pogostosti pojavljanja posameznih igralnih parametrov na tekmah smo dobili na podlagi uradnega beleženja, ki ga med tekmovanjem upravljajo usposobljeni merilci IHF z ustreznim računalniškim programom s pomočjo sprotnega zapisovanja na posebej pripravljen formular ter s pomočjo kasnejšega dodatnega pregleda tekem na video posnetkih.  
Ključne besede: rokomet, analize, metode dela, slovenska moška mladinska reprezentanca
Objavljeno: 20.05.2016; Ogledov: 273; Prenosov: 7
.pdf Polno besedilo (1,13 MB)

6.
Surface modification of silicone with polysaccharides for the development of antimicrobial urethral catheters
Matej Bračič, 2016, doktorska disertacija

Opis: In this work, alternative polysaccharide-based coatings were used to improve the antimicrobial and antifouling properties of silicone surfaces used for urethral catheters. The introduction of a catheter in the urethra is commonly connected with a high risk of microbial infections which often result in long-term health damage. Polysaccharide-based coatings like chitosan, carboxymethyl chitosan, and a synergistic formulation between hyaluronic acid and a natural lysine-based surfactant, were used to treat silicone surfaces to overcome the infection problems as an alternative to conventional approaches, which include the administration of antibiotics or coatings with metal ions. The polysaccharide-based macromolecular solutions and dispersions were firstly characterised by means of pH-titrations, dynamic light scattering and scanning electron microscopy in order to determine the size of particles in dispersions and their pH dependant charging behaviour. The knowledge gained from this was used to thoroughly study the interactions of the polysaccharide-based solutions and dispersions with the model silicone surfaces. The model surfaces were ultra-thin films prepared by dissolution of silicone in toluene and subsequent spin-coating on quartz crystals. The influence of pH, salt concentration, and various surface activation processes on the adsorption behaviour was evaluated by means of a very precise quartz crystal microbalance with dissipation. This knowledge was transferred to the application of the coatings on real systems i.e. casted silicone sheets and silicone tubes. The surface morphology, surface chemistry, as well as the mechanical and chemical stability of the coatings were further characterised on both model and real systems. For this purpose different microscopy and spectroscopy methods, pH-potentiometric titrations and methods for evaluation of mechanical properties were used. Finally the antimicrobial and antifouling properties were evaluated. The antimicrobial properties were tested against gram-positive and gram-negative bacteria as well as fungi, which are commonly found in infected urine, while the antifouling properties were tested by measuring the adhesion of bovine serum albumin, fibrinogen, and lysozyme biomolecules onto functionalised model films using the quartz crystal microbalance. The results showed that homogeneous and stable coatings can be achieved by adsorption from dispersions of the polysaccharide-based nanoparticles of 200-300 nm in size, which are formed by precipitation; i.e. careful pH adjustments of chitosan to pH = 6.5, carboxymethyl chitosan to pH = 7, and by mixing the hyaluronic acid and natural lysine-based surfactant solutions at concentrations of 2.5 x 10-4 mol/L and 1.25 x 10- 3 mol/L for the hyaluronic acid and 5.0 x 10-4 mol/L and 1.2 x 10-3 mol/L for the surfactant, respectively . The mass of the coatings on model silicone films can be increased by a 3-step adsorption, which directly influences the antimicrobial properties of the coatings that are improved with increasing coating mass, reaching values of up to 90 % in reduction of microorganism growth. It was also shown that the hyaluronic acid-natural surfactant formulation is superior to the chitosan coatings. The same conclusions were drawn from the antifouling evaluation where the zwitterionic nature of the formulation between natural based lysine surfactant and HA successfully suppressed the adhesion of biomolecules on silicone surfaces, while the chitosan coatings only moderately prevented the adhesion of proteins. One can conclude that the polysaccharide-based coatings can be successfully introduced to silicone surfaces from dispersion and as such successfully prevent biomolecule adhesion and reduce the growth of pathogen microorganisms which can be found in the urine during urethral infections.
Ključne besede: Urethral catheters, Antimicrobial coatings, Silicone, Polysaccharides, Natural surfactants
Objavljeno: 24.10.2016; Ogledov: 381; Prenosov: 41
.pdf Polno besedilo (5,86 MB)

7.
Izbira postroja za soproizvodnjo toplote in električne energije v podjetju Lentherm-invest d.o.o.
Matej Bračič, 2016, diplomsko delo

Opis: V diplomski nalogi je opisana ekonomska upravičenost vlaganja v soproizvodno enoto za podjetje Lentherm-invest d.o.o. V začetku diplomskega dela smo prikazali toplotne potrebe v podjetju, nato še potrebe po električni energiji. Na podlagi porabe toplote smo izbrali najprimernejšo soproizvodno enoto. Naredili smo primerjavo dveh soproizvodnih enot, ki sta se razlikovali po velikosti. Izračunali smo količino proizvedene toplote in električne energije iz vsake enote ter primanjkljaj, ki ga bomo pokrivali s starim kotlom na ELKO. Z izračunanjem neto sedanje vrednosti investicije smo preverili, s katero investicijo imamo v dvajsetih letih boljši donos. Izkazalo se je, da je v primeru porabe podjetja Lentherm-invest d.o.o. bolje izbrati zmogljivejšo soproizvodno enoto »indop 370M«, s katero bi v življenjski dobi enote privarčevali 1.860.020 €.
Ključne besede: Soproizvodnja, soproizvodna enota, električna energija, toplota, ekonomska upravičenost.
Objavljeno: 29.09.2016; Ogledov: 329; Prenosov: 6
.pdf Polno besedilo (2,92 MB)

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