| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme

Options:
  Reset


71 - 80 / 123
First pagePrevious page45678910111213Next pageLast page
71.
DOLOČEVANJE KADMIJA IN SVINCA V ZEMLJI Z ELEKTROTERMIČNO ATOMSKO ABSORPCIJSKO SPEKTROMETRIJO
Urban Senica, 2012, undergraduate thesis

Abstract: Namen diplomskega dela je bil validacija analizne metode za določanje vsebnosti kadmija in svinca v zemlji z elektrotermično atomsko absorpcijsko spektrometrijo (ETAAS). Kadmij in svinec smo določali po standardni metodi ISO 11047:1998 (Kakovost tal - Določevanje kadmija, kroma, kobalta, bakra, svinca, mangana, niklja in cinka - Metoda plamenske in elektrotermične atomske absorpcijske spektrometrije). Izvedena je bila validacija anlizne metode, pri kateri smo določili in preverili območje določanja, premosorazmernost signala in koncentracije v območju določanja, natančnost in točnost določitev ter časovno stabilnost preskusnih vzorcev. Ocenili smo merilno negotovost.
Keywords: kadmij, svinec, ETAAS, elektrotermična atomska absorpcijska spektrometrija, validacija
Published in DKUM: 16.10.2012; Views: 2880; Downloads: 466
.pdf Full text (2,26 MB)

72.
VPLIV BIOPROCESNIH PARAMETROV NA PROIZVODNJO CO 2 MED FERMENTACIJO LAKTOZE V MLEKU
Jasna Groman, 2012, undergraduate thesis

Abstract: V diplomskem delu je opisan postopek določanja vpliva bioprocesnih parametrov na proizvodnost CO2 pri fermentaciji laktoze v mleku. Eksperimente smo izvajali v šaržnem reaktorju, opremljenim z merilnikom CO2, ki je bil priklopljen na osebni računalnik, s katerim smo lahko 24 h beležili vsebnost CO2 v reaktorju. Laboratorijski del raziskav je bil sestavljen iz štirih sklopov. V prvem smo določili okvirno koncentracijo CO2 pri predhodno določenih optimalnih pogojih za rast zrn ter izbrali najprimernejši kinetični model. V drugem sklopu smo proučevali vpliv temperature fermentacije na proizvodnost CO2, maksimalno končno koncentracijo CO2 in dolžino lag faze. Tudi v tretjem in četrtem sklopu smo določali te tri kinetične parametre. Spreminjali smo koncentracijo glukoze v fermentacijskem mediju in vrtilno frekvenco mešala. Hkrati smo v vseh sklopih zasledovali tudi prirast mase kefirnih zrn. Rezultati raziskav nam omogočajo izbiro pravilne kombinacije nivojev bioprocesnih parametrov za izbrano proizvodnost CO2. Na osnovi določenih kinetičnih parametrov bi v nadaljevanju lahko dimenzinirali industrijski biofermentor.
Keywords: kefir, fermentacija, proizvodnost CO2, bioprocesni parametri, kinetični model
Published in DKUM: 05.10.2012; Views: 1943; Downloads: 157
.pdf Full text (1,76 MB)

73.
DOLOČEVANJE MONOSAHARIDOV S KAPILARNO ELEKTROFOREZO
Natalija Virant, 2012, undergraduate thesis

Abstract: Namen diplomskega dela je bil s pomočjo kapilarne elektroforeze kvalitativno in kvantitativno ovrednotiti sestavo monosaharidov v vzorcih kefirana. Optimirali smo celoten postopek z uporabo različnih dolžin kapilare ter različnih dodatkov acetonitrila k boratnemu pufru. Vzorce kefirana smo hidrolizirali s H2SO4, derivatizacijo pa smo izvedli z reduktivno aminacijo, ob uporabi natrijevega cianoborohidrida. Rezultati so pokazali, da kefiran vsebuje glukozo in galaktozo. Določili smo, da je skupna vrednost monosaharidov v območju od 29,2 % do 55,8 %. Koncentracija glukoze je bila v območju od 62,8 mg/L do 113,7 mg/L, medtem ko se je koncentracije galaktoze gibala med 55,2 mg/L in 110,1 mg/L. Ugotovili smo, da je najboljša ločljivost komponent potekla ob uporabi kapilare dolžine 37 cm in 30 % dodatkom acetonitrila k boratnemu pufru.
Keywords: kapilarna elektroforeza, elektroosmotski tok, monosaharidi, kefiran
Published in DKUM: 04.10.2012; Views: 2309; Downloads: 251
.pdf Full text (2,87 MB)

74.
VALIDACIJA IN DOLOČANJE MERILNE NEGOTOVOSTI SPEKTROFOTOMETRIČNE METODE FENOLNEGA INDEKSA (SIST ISO 6439:1996/A) ZA IZLUŽKE ODPADKOV IZRABLJENIH AKUMULATORJEV
Maja Padjen, 2012, undergraduate thesis

Abstract: V diplomskem delu sta bili izvedeni validacija in določitev merilne negotovosti fenolnega indeksa spektrofotometrične metode s 4-aminoantipirinom s predhodno destilacijo po SIST ISO 6439: 1996 metoda A. Izlužek odpadkov je bil pripravljen s postopkom ekstrakcije, kjer odstranjujemo iz trdnih zmesi topne komponente s topilom, ki je v našem primeru voda. Odpadek je opredeljen kot nevaren odpadek, saj vsebuje težke kovine – svinec, sestavljata pa ga še polipropilen in polivinil klorid. V izlužku odpadkov izrabljenih akumulatorjev smo spremljali koncentracijo fenolnega indeksa, ki po uredbi o odpadkih ne sme presegati 100 mg/l. Validacija analizne metode je obsegala določitev merilnega območja, mejo zaznavnosti in mejo določljivosti, linearnost, natančnost meritev, točnost in vpliv interferenc. Ko so bili doseženi predpisani parametri, predvsem linearnost in točnost metode, ter so bili tudi vsi ostali parametri pod predhodno določeno mejo, je bila validacija zaključena. Ugotovili smo, da merilna negotovost znaša ± 11% odstopanja od prave vrednosti rezultata (faktor pokritja k = 2 predstavlja 95% stopnjo zaupanja) in je bila določena po modelu, ki uporablja validacijske podatke.
Keywords: validacija, merilna negotovost, spektrofotometrija, fenolni indeks, izlužek odpadka
Published in DKUM: 11.09.2012; Views: 2045; Downloads: 278
.pdf Full text (2,94 MB)

75.
DOLOČANJE VSEBNOSTI SUHE SNOVI IN ŽARILNE IZGUBE PRI ODPADKIH
Mateja Ocvirk, 2012, undergraduate thesis

Abstract: Namen diplomskega dela je bil validacija gravimetrijske metode za določanje suhe snovi in suhega ostanka oziroma vode in validacija gravimetrijske metode za določevanje žarilne izgube odpadka, blata in sedimentov po standardu. Vpeljana je bila gravimetrijska metoda in v skladu s standardi SIST EN 14 346 in SIST EN 15 169 je bila preizkušena meja zaznavnosti, meja določljivosti, natančnost, točnost, pravilnost, merilna negotovost in statistično obdelani podatki obeh metod. Analizirani so bili realni vzorci (odpadki, blato in sedimenti), ki predstavljajo reprezentativne vzorce pri delu na Zavodu za zdravstveno varstvo Celje. Dokazano je da, sta predlagani gravimetrijski metodi primerni, natančni in točni.
Keywords: suha snov, žarilna izguba, odpadki, gravimetrija, validacija.
Published in DKUM: 11.09.2012; Views: 3560; Downloads: 528
.pdf Full text (2,40 MB)

76.
RAZVOJ IN KARAKTERIZACIJA OPTIČNIH Ru - SENZORJEV ZA DOLOČANJE KISIKA
Maja Kelc, 2012, undergraduate thesis

Abstract: Rutenijevi kompleksi so daleč najbolj razširjeni O2 indikatorji, ker imajo učinkovito luminescenco, relativno stabilen kovina – ligand prenos naboja vzbujenega stanja, hiter odzivni čas, močno vidno absorpcijo, velike Stokes – ove preskoke in visoko fotokemično stabilnost. V diplomski nalogi smo za izdelavo senzorjev uporabili različne koncentracije rutenijevega kompleksa v različnih topilih. Preizkusili smo različne PVC folije uporabljene kot nosilec. Na »Spin – coaterju« smo optimirali program s katerim smo dobili optično gledano najbolj homogene nanose senzorskih raztopin. Senzorje smo izpostavili različnim koncentracijam kisika. Linearnost smo preverili v območju od 0 do 100 % koncentracije kisika. Ugotovili smo linearnost za senzorje pripravljene iz 60 in 80 mg rutenijevega kompleksa. »Spin – coating« se je izkazal kot alternativna metoda za nanos senzorskih raztopin, vendar po celotni senzorski površini ni možno pripraviti homogenega nanosa, kar smo pokazali tudi z opravljenimi SEM posnetki. Za nanašanje senzorskih raztopin na nosilec bi v bodoče uporabili mehanski nanos z natančnim nožem.
Keywords: Optični kemijski senzorji, senzorji za določanje kisika, »Spin – coating«, (Ru-(II) tris(4, 7- difenil-1, 10-fenantrolin) ClO4)2
Published in DKUM: 21.06.2012; Views: 2420; Downloads: 237
.pdf Full text (3,62 MB)

77.
Determination of oxygen by means of a biogas and gas - interference study using an optical tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex sensor
Polonca Brglez, Andrej Holobar, Aleksandra Pivec, Nataša Belšak, Mitja Kolar, 2012, original scientific article

Abstract: Biogas is a mixture of gases produced by anaerobic fermentation where biomass or animal waste is decomposed and methane and carbon dioxide are mainly released. Biogas also has a very high moisture content (up to 80%), temperatures of around 60 °C, high pressure, and can contain other gases ($N_2$, $H_2S$, $NH_3$ and $H_2$). We searched for an appropriate measuring system for the determining of oxygen in biogas, since the production process of biogas must be run under anaerobic conditions; as the presence of oxygen decreases the quality of the biogas. Ruthenium (II) complexes are by far the most widely-used oxygen dyes within optical oxygen sensors. In general, they have efficient luminescences, relatively long-life metal-ligand charge-transfer excited states, fast response times, strong visible absorptions, large Stokes shifts, and high-photochemical stability. The purpose of this work was to characterise and optimize an optical oxygen sensor using tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex for measuring oxygen. Different sensor properties were additionally studied, focusing on the interference of external light, temperature, and various gases. A special gas-mixing chamber was developed for gas interference study, and online experiments are presented for oxygen determination within the pilot biogas reactor.
Keywords: tris(4, 7-diphenyl-1, 10-phenanthroline)ruthenium(II) dichloride complex, oxygen optical sensor, interferences, biogas
Published in DKUM: 01.06.2012; Views: 2113; Downloads: 108
.pdf Full text (315,15 KB)
This document has many files! More...

78.
Binding silver nano-particles onto viscose non-woven using different commercial sol-gel procedures
Tanja Pivec, Zdenka Peršin Fratnik, Silvo Hribernik, Tina Maver, Mitja Kolar, Karin Stana-Kleinschek, 2012, original scientific article

Abstract: The paper presents possible solution of Ag binding using commercial sol-gel systems which enable its low release into a wound, providing a good antimicrobial effect on those bacterial cultures that are most likely present in the wound. The influence of different sol-gel systems on the hydrophilic properties of carrier materials and the level of released silver has been studied. The results showed that sol-gel as binding-systems could provide proper hydrophilic properties of material, whilst binding silver strongly enough providing at the same time excellent antimicrobial activity of the treated viscose meterials.
Keywords: silver nano-particles, sol-gel, viscose non-woven, silver release, hydrophilicity, antimicrobial properties
Published in DKUM: 01.06.2012; Views: 3041; Downloads: 100
.pdf Full text (235,88 KB)
This document has many files! More...

79.
Comparison of the effectiveness of standard and drift-reducing nozzles for control of some pests of apple
Mario Lešnik, Cvetka Pintar, Aleksandra Lobnik, Mitja Kolar, 2005, original scientific article

Abstract: A comparison of the biological efficacy of pesticides applied against some apple pests with standard versus drift-reducing nozzles was made in trials in intensive orchards in Slovenia. Standard and drift-reducing nozzles were compared by applying 350 L spray per hectare. No significant differences in acaricide/insecticide efficacy between the types of nozzles could be observed when controlling fruit tree red spider mite (Panonychus ulmi) and apple rosy aphid (Dysaphis plantaginea). However, drift-reducing nozzles reduced the efficacy of insecticides against the codling moth (Cydia pomonella), green apple aphid (Aphis pomi) and apple leaf miner (Leucoptera malifoliella).
Keywords: apple, spraying, drift-reducing nozzles, biological efficacy, insecticides, Aphis pomi, Cydia pomonella, Dysaphis plantaginea, Leucoptera malifoliella, Panonychus ulmi
Published in DKUM: 01.06.2012; Views: 1870; Downloads: 114
URL Link to full text

80.
Tungsten - tungsten trioxide electrodes for the long-term monitoring of corrosion processes in highly alkaline media and concrete-based materials
Mitja Kolar, Aleš Doliška, Franc Švegl, Kurt Kalcher, 2010, original scientific article

Abstract: The determination of pH in highly alkaline solutions and concrete materials is extremely important for monitoring or predicting the corrosion processes of reinforced concrete structures and to follow the hydration process of Portland cement, fly-ash, micro silica and other materials used in concrete manufacturing. The corrosion of reinforced concrete structures and the hydration of pozzolanic materials are long-term processes, which means, that appropriate durable, and resilient pH electrodes are needed, for direct implantation regarding solid concrete bodies. The purpose of this work was to characterise the potentiometric and surface properties of tungsten electrodes after exposure to extreme alkaline solutions. The tungsten wire surface was activated at 800 °C for 30 min within an oxygen flow. The formation of homogenous and compact multiple layers of $WO_3$ crystals was observed using X-ray diffraction and scanning electron microscopy. X-ray diffraction of thosetungsten electrodes exposed to saturated calcium hydroxide solution or the pore-water of cement-based materials during 10 months, indicated partly dissolved $WO_3$. Two new compounds appeared on the electrodes surfaces; pure tungsten and $CaWO_4$. The presence of tungsten was affecting any potentiometric response in acidic pH region (2-5) but in pH 5-12 region the response still remained linear with a slope of 42 2 mV/pH unit. The $W/WO_3$ electrode was suitable for the long-term monitoring of corrosion processes in concrete-basedmaterials according to the pH changes as it has stable and repeatable responses to alkaline solutions (pH > 12). All the tested interferring ions had no significant influence on electrode potential. The $W/WO_3$ electrode is simple, robust, inexpensive, and temperature resistant and can be applied in potentiometric titrations as well as in batch and flow-injection analysis. The prepared electrode is a highly promising pH sensor for the monitoring of pH changes in highly alkaline capillary water of concrete.
Keywords: potentiometry, pH, tungsten - tungsten trioxide, pore water, concrete, flow-injection analysis
Published in DKUM: 31.05.2012; Views: 2390; Downloads: 103
.pdf Full text (1,67 MB)
This document has many files! More...

Search done in 0.43 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica