1. Okoljska ocena tveganja fungicida folpeta za talne ekosistemeAna Karat, 2018 Opis: Folpet uvrščamo med najpogosteje uporabljene fungicide za preprečevanje in zdravljenje dveh vrst plesni vinske trte. Njegova uporaba je omejena na vinograde z izjemo enega pripravka, ki ga lahko uporabljamo tudi za zdravljenje zelenjave in oljk (MKGP, 2017). Pripravek, ki smo ga uporabili v magistrskem delu je Folpan 80 WDG, ki z raztapljanjem v vodi daje raztopino za škropljenje vinskih trt.
Folpet smo preučevali kot okoljski stresor za talne ekosisteme s poudarkom na njegovem vplivu na organizme. Prst smo vzorčili tri leta zapored v lokalnem vinogradu. S pomočjo obstoječe literature smo optimizirali metodo ekstrakcije folpeta iz naravne prsti z uporabo avtomatizirane visokotlačne tekočinske (PLE) ekstrakcije. Pokazali smo, da je folpet s pravilnim načinom vzorčenja, shranjevanja in ekstrahiranja mogoče izmeriti v naravnih vzorcih prsti. Najvišja izmerjena koncentracija je bila 3,76 mg/kg, povprečni razpolovni čas folpeta v prsti je bil 2,3 ± 1,4 dni.
Izmerjene koncentracije folpeta smo uporabili za izračun tveganja za talne organizme. Z uporabo ekotoksikoloških izogibnostnih testov na deževnikih in izopodih smo dobili koncentracijo brez vpliva na organizme (NOEC) 1,31 ± 0,01 mg/kg. Razmerje med okoljsko koncentracijo folpeta in koncentracijo, ki ne vpliva na talne organizme (PEC/PNEC) je bilo 28 v najslabšem primeru ob najvišji koncentraciji folpeta v tleh. Rezultat nakazuje na možen negativen vpliv folpeta na talno favno, vendar smo zaradi hitrega razpada folpeta v prsti tveganje za talne nevretenčarje ovrednotili kot zelo nizko in folpet priporočali za nadaljnjo rabo v vinogradništvu.
Ključne besede: folpet, okoljska ocena tveganja, talni ekosistemi, fungicid, prst
Objavljeno: 16.02.2018; Ogledov: 1350; Prenosov: 88
 Polno besedilo
Ogledov v tednu: 130 |
2. PHOTO-EXCITATION ENERGY INFLUENCE ON THE PHOTOCONDUCTIVITY OF ORGANIC SEMICONDUCTORSNadiia 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: 1047; Prenosov: 42
Polno besedilo
Ogledov v tednu: 123 |
3. EFFECTS OF POTENTIAL CLIMATE CHANGES ON THE BEHAVIOUR, FEEDING RATE AND REPRODUCTION OF SELECTED SOIL INVERTEBRATESNijat Rahimli, 2018 Opis: As a consequence of global climate change, the biodiversity of soil invertebrates is impacted. Elevated temperatures and moisture alterations in soil have deleterious effects on soil invertebrates. These organisms are important bioindicators of changes in soil ecosystems. Therefore, we investigated the effect of soil moisture, as potential impacts of climate change, on the behaviour, feeding rate and reproduction rates of two soil invertebrate species: woodlice (Porcellio scaber) and earthworms (Eisenia andrei) in laboratory experiments. Our results indicate that soil invertebrates are highly sensitive to desiccation. The feeding activity of woodlice and the reproduction rate of earthworms are likely dependent on soil moisture.
Ključne besede: Climate change, Soil invertebrates, Soil ecology, Isopods, Earthworms
Objavljeno: 14.02.2018; Ogledov: 1236; Prenosov: 115
Polno besedilo
Ogledov v tednu: 61 |
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5. Komparativna analiza procesa proizvodnje ventilatorjev v podjetju Hidria Rotomatika; primerjava tipov ventilatorjev z vidika življenjskega ciklaMerisa 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: 96; Prenosov: 5
Polno besedilo
Ogledov v tednu: 44 |
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