Repozitorij Univerze v Novi Gorici

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Največkrat ogledana gradiva tedna (zadnjih 7 dni).

Weak embeddable hypernear-rings
Jelena Dakić, Sanja Jančić-Rašović, Irina Cristea, 2019

Ključne besede: hypernear-ring, multitransformation, embedding
Objavljeno: 07.08.2019; Ogledov: 570; Prenosov: 8
.pdf Polno besedilo
Ogledov v tednu: 327

Komparativna analiza procesa proizvodnje ventilatorjev v podjetju Hidria Rotomatika; primerjava tipov ventilatorjev z vidika življenjskega cikla
Merisa Kapić, 2019

Opis: V magistrskem delu je z metodo analize življenjskega cikla ocenjen vpliv na okolje dveh ventilatorjev proizvajalca Hidria Rotomatika: starejši model R-11 in novejši HEC-10. Analiza zajema proizvodno fazo in fazo uporabe izdelka, medtem ko je faza razgradnje zaradi kompleksnosti in pomanjkanja podatkov iz analize vseživljenjskega cikla izključena. Analiza je pokazala, da ima v proizvodni fazi novejši model HEC-10 nekoliko manjši negativni vpliv na okolje. Model R-11 ima večji negativni vpliv na okolje v skoraj vseh kategorijah, razen kategorij raba tal in izraba mineralnih virov. Model R-11 ima za 8,8 % večji vpliv na zdravje ljudi in za 6,9 % večji vpliv na izrabo virov, medtem ko ima na drugi strani model HEC-10 za 5,1 % večji vpliv na kakovost ekosistemov. Večja razlika med ventilatorjema nastane v fazi uporabe, kjer model HEC-10 pokaže sodobno zasnovo in je zaradi manjše rabe energije prijaznejši okolju. Pri vseh kategorijah je poleg izrabe mineralnih virov imela poraba električne energije med obratovanjem največji negativni vpliv na okolje. Na zmanjšanje negativnega vseživljenjskega vpliva obeh ventilatorjev na okolje je torej ključnega pomena zmanjšanje rabe električne energije v fazi uporabe. 
Ključne besede: Analiza življenjskega cikla, življenjski cikel izdelka, ventilatorji, vpliv na okolje, industrijska ekologija
Objavljeno: 30.10.2019; Ogledov: 89; Prenosov: 4
.pdf Polno besedilo
Ogledov v tednu: 57

Nadiia Pastukhova, 2018

Opis: In this work, we experimentally studied the influence of photoexcitation energy influence on the charge transport in organic semiconductors. Organic semiconductors were small molecules like corannulene, perylene and pentacene derivatives, polymers such as polythiophene and benzothiophene derivatives, and graphene, along with combinations of these materials in heterojunctions or composites. The first part of this study is focused on the photoexcitation energy influence on the transient photoconductivity of non-crystalline curved π-conjugated corannulene layers. The enhanced photoconductivity, in the energy range where optical absorption is absent, is deduced from theoretical predictions of corannulene gas-phase excited state spectra. Theoretical analysis reveals a consistent contribution involving transitions to Super Atomic Molecular Orbitals (SAMOs), a unique set of diffuse orbitals typical of curved π-conjugated molecules. More, the photoconductivity of the curved corannulene was compared to the π-conjugated planar N,N′-1H,1H- perfluorobutyldicyanoperylene-carboxydi-imide (PDIF-CN2), where the photoexcitation energy dependence of photocurrent closely follows the optical absorption spectrum. We next characterized charge transport in poly(3-hexylthiophene) (P3HT) layers deposited from solution. Our results indicate that time-of-flight (TOF) mobility depends on the photoexcitation energy. It is 0.4× 10 −3 cm 2 /Vs at 2.3 eV (530 nm) and doubles at 4.8 eV (260 nm). TOF mobility was compared to field-effect (FET) mobility of P3HT field-effect transistors (OFETs). The FET mobility was similar to the 2.3 eV excitation TOF mobility. In order to improve charge mobility, graphene nanoparticles were blended within a P3HT solution before the deposition. We found that the mobility significantly improves upon the addition of graphene nanoparticles of a weight ratio as low as 0.2 %. FET mobility increases with graphene concentration up to a value of 2.3× 10 −2 cm 2 /Vs at 3.2 %. The results demonstrate that phase segregation starts to influence charge transport at graphene concentration of 0.8 % and above. Hence, the graphene cannot form a bridged conduction channel between electrodes, which would cancel the semiconducting effect of the polymer composite. An alternative approach to enhance mobility is to optimize the molecular ordering of organic semiconductors. For that purpose, we studied an innovative nanomesh device. Free-standing nanomesh devices were used to form nanojunctions of N,N′- iiDioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) nanowires and crystalline bis(triisopropylsilylethinyl)pentacene (TIPS-PEN). We characterized the photocurrent response time of this novel nanomesh scaffold device. The photoresponse time depends on the photon energy. It is between 4.5 − 5.6 ns at 500 nm excitation wavelength and between 6.7 − 7.7 ns at 700 nm excitation wavelength. In addition, we found that thermal annealing reduces charge carrier trapping in crystalline nanowires. This confirms that the structural defects are crucial to obtaining high photon-to-charge conversion efficiency and subsequent transport from pn junction in heterostructured materials. Structural defects also influence the power conversion efficiency of organic heterostructured photovoltaics (OPVs). Anticipating that polymers with different backbone lengths produce different level of structural defects, we examined charge transport dependence on the molecular weight of poly[4,8-bis(5-(2- ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2- ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl] (PTB7-Th) from 50 kDa to 300 kDa. We found p-type hopping transport in PTB7-Th, characterized by 0.1 – 3× 10 −2 cm 2 /Vs mobility, which increases with temperature and electric field. The polymer molecular weight exhibits a non-trivial influence on charge transport. FET mobility in the saturation regime increases with molecular weight. A similar trend is observed in TOF mobility and FET mobility in the linear regime, except for the 100kDa polymer, which manifests in the highest mobility due to reduced charge trapping. The lowest trapping at the dielectric interface of OFET is observed at 200 kDa. In addition, the 200 kDa polymer exhibits the lowest activation energy of the charge transport. Although the 100 kDa polymer indicates the highest mobility, OPVs using the 200 kDa polymer exhibit the best performance in terms of power conversion efficiency.
Ključne besede: organic semiconductors, optical absorption spectroscopy, time-of-flight photoconductivity, transient photocurrent spectroscopy, organic thin film transistors, atomic force microscopy, superatomic molecular orbitals, pn heterojunction, organic nanowires, graphene, composites, charge mobility, charge trapping, temperature dependence, photodetector, photovoltaic, solar cell, organic electronics
Objavljeno: 08.10.2018; Ogledov: 947; Prenosov: 42
.pdf Polno besedilo
Ogledov v tednu: 57

Ketevan Neparidze, 2017

Opis: Over the last few decades, numerous pharmaceuticals coming from domestic sewage, livestock, hospitals and industries have been determined in ground, surface and drinking waters. A common example of these pollutants are fluoroquinolones, which are powerful antibiotics used in human and veterinary medicine. The presence of fluoroquinolones in the environment even at low concentration constitutes a threat to ecosystems and human health because they can lead to bacterial resistance issues. Up to now the environmental impacts of fluoroquinolones and their degradation products are not fully understood but it is known that they can negatively affect plants and aquatic organisms. In this study the degradation of ciprofloxacin (CIP) present in synthetic freshwater was investigated under simulated sunlight. Concentrations before and after degradation were determined using HPLC-DAD. The mineralisation rate of the treated solution was monitored on a total organic carbon analyser. The ecotoxicity of the initial samples and the degradation mixtures was assessed on organisms belonging to different trophic levels: a marine bacterium (Vibrio fischeri), a freshwater invertebrate (Daphnia magna) and seed clover (Trifolium repens). In parallel, the EC50 of CIP was determined for all organisms. The Vibrio fischeri and Trifolium repens tests showed that EC50 value was more than 250 mg/L and for Daphnia magna was 190 mg/L. Photolysis of CIP showed that after 90 min of irradiation, CIP was almost totally degraded (99%). Photolysis process of CIP led to the formation of toxic by-products towards Vibrio fischeri. The toxicity test results on Trifolium repens did not show significant difference between the control and the treated plants. Thus, CIP and its degradation products have no effect on the germination or root length of Trifolium repens. Tests on Daphnia magna after 240 min irradiation showed a 94% reduction of the toxic effect. Non-purgeable organic carbon (NPOC) analysis showed that there is no significant mineralisation of the sample even after 240 min of irradiation.
Ključne besede: Key words: fluoroquinolones, ciprofloxacin, photolysis, toxicity tests, EC50 determination
Objavljeno: 31.01.2017; Ogledov: 2135; Prenosov: 155
.pdf Polno besedilo
Ogledov v tednu: 56

On the nature of prenumeral adjectives
Rok Žaucer, Franc Marušič, 2019

Opis: Following Greenberg’s generalization 20 prenominal adjectives follow numerals. In this paper we discuss a group of adjectives that appear in unexpected positions: adjectives preceding numerals prenominally. We argue that these adjectives violate cross-linguistic generalizations only apparently, as the noun phrases with such adjectives actually contain additional covert structure – structure that is not realized phonologically/phonetically.
Ključne besede: Greenberg’s generalization 20, adjectives, numerals, noun phrase, Slovenian syntax
Objavljeno: 05.11.2019; Ogledov: 46; Prenosov: 0
.pdf Polno besedilo
Ogledov v tednu: 46

Scalar Implicatures

Opis: Scalar implicatures have enjoyed the status of one of the most researched topics in both theoretical and experimental pragmatics in recent years. This Research Topic presents new developments in studying the comprehension, as well as the production of scalar inferences, suggests new testing paradigms that trigger important discussions about the methodology of experimental investigation, explores the effect of prosody and context on inference rates. To a great extent the articles reflect the state of the art in the domain and outline promising paths for future research.
Ključne besede: Scalar implicature, Lexical scales, Scalar variability, Cross-linguistic variation, Production, Comprehension, Prosody, Context
Objavljeno: 06.11.2019; Ogledov: 44; Prenosov: 3
.pdf Polno besedilo
Ogledov v tednu: 44

DPs, IPs and (multiple) wh-fronting
Petra Mišmaš, 2019

Ključne besede: wh-fronting, wh-phrase, nominal domain, clause, Slovenian
Objavljeno: 05.11.2019; Ogledov: 44; Prenosov: 0
.pdf Polno besedilo
Ogledov v tednu: 44