1. PREVENTION AND MANAGEMENT OF LEGIONELLA SPP. SPREAD IN HOSPITAL WATER SYSTEM (ESTABLISHING AN EFFECTIVE SYSTEM WITHOUT USING CHEMICALS IN UNIVERSITY CLINIC OF RESPIRATORY AND ALLERGIC DISEASES GOLNIK)Mojca Novak, 2016, magistrsko delo Opis: The hospital water system can be a causative agent for acquiring hospital-acquired infection. Many microorganisms can be detected in potable water and one of this is Legionella spp. These bacteria live also in nature, but are usually present in low numbers. When entering into the buildings and their water supply, Legionella finds ideal conditions to multiply, especially if this systems are extensive and old. To control the conditions in the levels that cannot harm humans, many procedures – physical and chemical – have been established. All of them have advantages as well as limitations. According to these facts, in University Clinic of Respiratory and Allergic Diseases Golnik we tried to reestablish the protocols that would keep us on the safe side and be environmentally and health friendly as well. We have been trying to use the protocol without added chemicals – just with maintaining proper temperatures, heat disinfection and flushing for many years now. With this study we wanted to extend our knowledge of our hospital water system, so we intensified the sampling and introduced extended measures. We found out that the presence of Legionella in water system is connected to moderate temperatures and it is present more frequently in high risk zones (inappropriate temperatures, dead legs, water stagnation). With constant measures, the Legionella can be controlled but not eradicated. To contain it on a safe level, the group of experts must work together and introduce procedures that will provide safe environment for the patients and employees. Najdeno v: ključnih besedah Ključne besede: Legionella spp., hospital water system, prevention, temperature, flushing. Objavljeno: 30.09.2016; Ogledov: 5320; Prenosov: 269
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2. Pursuing the stabilisation of crystalline nanostructured magnetic manganites through a green low temperature hydrothermal synthesisPaolo Dolcet, Arianna Minelli, Stefano Diodati, Sandra Gardonio, Claudia Innocenti, Denis Badocco, Stefano Gialanella, Paolo Pastore, Luciano Pandolfo, Andrea Caneschi, Angela Trapanati, Silvia Gross, 2017, izvirni znanstveni članek Opis: A quick, easy and green water-based synthesis protocol involving coprecipitation of oxalates combined with hydrothermal treatment resulted in the crystallisation of nanostructured manganites at a relatively low temperature (180 °C). The subcritical hydrothermal approach was shown to play a key role in stabilising phases which are generally achieved at much higher temperatures and under harsher conditions, thus disclosing an exciting alternative for their synthesis. Through this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3 were synthesised as nanocrystalline powders. Noticeably, the optimised route proved to be effective in stabilising the exotic polymorph cubic spinel ZnMnO3 in pure form. This is particularly notable, as very few records concerning this compound are available in the literature. The compounds were fully characterised from compositional, structural, morphological and magnetic points of view. Najdeno v: ključnih besedah Ključne besede: nanostructured manganites, low temperature wet chemistry synthesis Objavljeno: 28.03.2017; Ogledov: 3681; Prenosov: 0
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3. Transparent titania-zirconia thin films for self-cleaning and photocatalytic applicationVlasta Brezová, Kandalam Ramanujachary, Nives Vodišek, Urška Lavrenčič Štangar, 2016, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Thin films were prepared by sol-gel process, where different amount of zirconia were added to titania.
Photocatalytic activity of thin films was measured by two methods i) determination of degradation ration of methyl stearate with measuring the contact angle and ii) formation of hydroxyterephthalic acid was measured by spectrofluorometer.
Prepared samples were characterized by UV-Vis spectrophotometer, SEM, XRD, FT-IR ATR, and BET.
The result of measurements of photocatalytic activity shows that the highest activity has a sample without addition of zirconia, but mechanical stability of that sample is worse. Najdeno v: ključnih besedah Povzetek najdenega: ...photocatalysis, ZrO2/ TiO2, thin films, self-cleaning, low-temperature, sol-gel process... Ključne besede: photocatalysis, ZrO2/ TiO2, thin films, self-cleaning, low-temperature, sol-gel process Objavljeno: 14.03.2017; Ogledov: 4391; Prenosov: 197
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4. PHOTO-EXCITATION ENERGY INFLUENCE ON THE PHOTOCONDUCTIVITY OF ORGANIC SEMICONDUCTORSNadiia Pastukhova, 2018, doktorska disertacija 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. Najdeno v: ključnih besedah 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: 4485; Prenosov: 156
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7. Temperature-controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflowMalin Alsved, A. Civilis, P. Ekolind, Tina Šantl Temkiv, Jakob Löndahl, 2017, izvirni znanstveni članek Najdeno v: ključnih besedah Ključne besede: Surgical site infection, BioTrak, Fluorescence, Energy efficiency, Temperature-controlled ventilation, Air sampling Objavljeno: 04.01.2021; Ogledov: 1637; Prenosov: 0
Polno besedilo (1,99 MB) |
8. Sn-modified TiO[sub]2 thin film photocatalysts prepared by low-temperature sol-gel processingKsenija Maver, 2021, doktorska disertacija Opis: Due to many advantageous physiochemical properties, titanium dioxide (TiO2) is the most widely used photocatalyst in numerous applications, such as wastewater treatment and air purification, self-cleaning surfaces and energy conversion (H2 generation). However, one of its disadvantages is the high electron-hole recombination rate, and coupling with other semiconductors is one of the strategies to improve it. The objective of this dissertation was to investigate how the photocatalytic activity of pure TiO2 can be improved by tin modification and to explain the mechanism of increased or hindered photoactivity in correlation with the structural properties of the modified TiO2 photocatalysts.
A new low-temperature sol-gel synthesis route was developed to prepare Sn- or SnO2-modified TiO2 photocatalysts. In both cases, organic tin and titanium precursors were used. Tin in the form of Sn cations was used to prepare Sn-modified TiO2. In this case, the precursors went through the sol-gel reaction together to form a Sn-TiO2 sol. In the case of SnO2 modification, the SnO2 sol was prepared separately and additionally mixed with the TiO2 sol to form a TiO2/SnO2 bicomponent semiconductor system. Different molar ratios of tin to titanium were prepared to investigate the correlation between the tin concentration and the photocatalytic properties of the photocatalysts in the form of thin films. The results were used to optimize the synthesis conditions to obtain an improved activity of the modified TiO2 photocatalysts under UV-irradiation.
The photocatalytic activity of the thin films was determined by measuring the degradation rate of an azo dye. An increase of up to 40 % in the photocatalytic activity of the dried samples (at 150 °C) was achieved when the TiO2 was modified with the Sn or SnO2 in a concentration range of 0.1 to 1 mol.%. At higher Sn or SnO2 loadings and after calcination of the samples at 500 °C, the photocatalytic activity of the photocatalyst was reduced compared to the unmodified TiO2.
Different characterization techniques (UV-Vis, XRD, nitrogen physisorption, TEM, SEM and XAS) were employed to clarify the mechanism responsible for the enhanced and hindered photocatalytic performance of the Sn- and SnO2-modified TiO2 photocatalysts. The results showed that a nanocrystalline structure is already achieved in the samples by the low-temperature film treatment (drying at 150 °C) and that the photocatalytic efficiency is mainly influenced by the crystalline phase composition: anatase/rutile in the case of Sn-modified and TiO2/SnO2 in the case of SnO2-modified TiO2. The crystal size and specific surface area differ insignificantly between the equally thermally treated samples and partly explain the differences in photoefficiency of the calcined samples compared to the dried samples. The structural study at the atomic level, using the Sn K-edge EXAFS, revealed that Sn cations act as nucleation sites for the anatase to rutile transformation in the Sn-modified TiO2 photocatalysts, while in the SnO2-modified TiO2 samples the nanocrystalline cassiterite SnO2 is bound to the TiO2 nanocrystallites via the Sn-O-Ti bond. In both cases, the advantage of coupling the two semiconductors was achieved by separating the charge carriers and thus prolonging their lifetime for accessibility to participate in the redox reactions. The maximum activity enhancement was achieved in the low concentration range (0.1–1 mol.%), which means that an optimal ratio and contact of the two phases are obtained for the given physical parameters, such as particle size, shape and specific surface area of the catalyst. Najdeno v: ključnih besedah Ključne besede: Sn-modified TiO2, SnO2-modified TiO2, low-temperature sol-gel, thin films, photocatalytic activity, anatase/rutile system, Sn K-edge EXAFS, dissertations Objavljeno: 09.06.2021; Ogledov: 3144; Prenosov: 148
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9. Improved photocatalytic activity of SnO[sub]2-TiO[sub]2 nanocomposite thin films prepared by low-temperature sol-gel methodUrška Lavrenčič Štangar, Giovanni Palmisano, Matjaž Valant, Mattia Fanetti, Samar Al Jitan, Iztok Arčon, Ksenija Maver, 2021, izvirni znanstveni članek Opis: The objective of this research was to investigate how the photocatalytic activity of pure TiO2 can be improved by
SnO2 modification. Different molar ratios of tin to titanium were prepared. The correlation between tin concentration
and structural properties was investigated to explain the mechanism of photocatalytic efficiency and
to optimize the synthesis conditions to obtain enhanced activity of the SnO2-modified TiO2 photocatalysts under
UV-irradiation. The SnO2-modified TiO2 photocatalysts were prepared by a low-temperature sol-gel method
based on organic tin and titanium precursors. The precursors underwent sol-gel reactions separately to form
SnO2-TiO2 sol. The sol-gels were deposited on a glass substrate by a dip-coating technique and dried at 150 ◦C to
obtain the photocatalysts in the form of a thin film. To test the thermal stability of the material, an additional set
of photocatalysts was prepared by calcining the dried samples in air at 500 ◦C. The photocatalytic activity of the
samples was determined by measuring the degradation rate of an azo dye. An increase of up to 30% in the
photocatalytic activity of the air-dried samples was obtained when the TiO2 was modified with the SnO2 in a
concentration range of 0.1–1 mol.%. At higher SnO2 loadings, the photocatalytic activity of the photocatalyst
was reduced compared to the unmodified TiO2. The calcined samples showed an overall reduced photocatalytic
activity compared to the air-dried samples. Various characterization techniques (UV-Vis, XRD, N2-physisorption,
TEM, EDX, SEM, XAS and photoelectrochemical characterization) were used to explain the mechanism for the
enhanced and hindered photocatalytic performances of the SnO2-modified TiO2 photocatalysts. The results
showed that the nanocrystalline cassiterite SnO2 is attached to the TiO2 nanocrystallites through the Sn-O-Ti
bonds. In this way, the coupling of two semiconductors, SnO2 and TiO2, was demonstrated. Compared to
single-phase photocatalysts, the coupling of semiconductors has a beneficial effect on the separation of charge
carriers, which prolongs their lifetime for accessibility to participate in the redox reactions. The maximum increase
in activity of the thin films was achieved in the low concentration range (0.1–1 mol.%), which means that
an optimal ratio and contact of the two phases is achieved for the given physical parameters such as particle size,
shape and specific surface area of the catalyst. Najdeno v: ključnih besedah Ključne besede: photocatalytic activity, Sn-modified TiO2, low-temperature, thin films, XAS analysis Objavljeno: 05.07.2021; Ogledov: 1384; Prenosov: 0
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10. Berry primary and secondary metabolites in response to sunlight and temperature in the grapevine fruit zoneGuillaume Antalick, Anne Pellegrino, Alain Deloire, Suzy Y. Rogiers, 2020, strokovni članek Opis: The chemical composition of berries at harvest, which will affect wine styles, is determined by complex physiological processes occurring from set through the fruit’s lifetime to maturity, and this is closely intertwined with environmental and crop management factors. Among those factors, climatic conditions within the fruit zone (i.e. microclimate), such as light and temperature, are well-known to affect the physiology of the fruit at the skin, pulp and seed levels. This article will present the potential of leaf thinning in the bunch zone to modify cluster microclimate and berry composition. Najdeno v: ključnih besedah Ključne besede: berry primary metabolites, berry secondary metabolites, fruit zone, sunlight, temperature Objavljeno: 21.09.2021; Ogledov: 1112; Prenosov: 121
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