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1.
Thermal lens spectrometry - still a technique on the horizon?
Mladen Franko, 2015

Opis: In 1980’s thermal lens spectrometry (TLS) was still considered as a “spectrometric technique on the horizon” as one can also read from one of the textbooks on spectrochemical analysis of that time. Intensive development of thermal lens instrumentation and methods of chemical analysis and material characterisation has however resulted in substantial progress in this field, which is evident from important instrumental innovations and first commercial instruments (i.e. thermal lens microscopes -TLM) designed for lab-on-a-chip chemistry as well as from novel applications of TLS in various areas, where highly sensitive and rapid chemical analysis of complex samples is needed, including food safety and quality control, environmental analysis and biomedical diagnostics. This presentation is a review of most significant contributions and applications of thermal lens spectrometry, with emphasis on most recent achievements in instrumentation, which culminated into construction of novel optimized TLM instruments, capable of exploiting the tuneability of incoherent light sources and enabled novel applications particularly in micro-fluidics. Based on latest progress relying on bio-analytical assays and micro-fluidic flow injection with TLM detection we have also witnessed firs routine applications of TLS in analytical and diagnostic laboratories, which on wine side actually classifies TLS as a conventional and routine analytical tool, but at the same time opens new horizons for development and applications of this ultrasensitive and rapid spectrometric technique.
Najdeno v: ključnih besedah
Povzetek najdenega: ...from one of the textbooks on spectrochemical analysis of that time. Intensive development of thermal...
Ključne besede: Thermal lens spectrometry, applications, Liquid chromatography, flow injection analysis, bioanalytical methods
Objavljeno: 29.03.2016; Ogledov: 1777; Prenosov: 0
.pdf Polno besedilo (609,15 KB)

2.
Thermal Lens Spectrometry: Still a Technique on the Horizon
Mladen Franko, Mingqiang Liu, 2016, objavljeni znanstveni prispevek na konferenci

Opis: In this article the historical development of thermal lens spectrometry (TLS) is briefly reviewed for introduction. In continuation, the emphasis is on the recent progresses of TLS for measurements in ensembled sample cells and in microfluidic flow injection systems. Novel theories, instrumentations and their applications for high sample throughput environmental, chemical and biomedical analysis, particularly in micro space, are presented. Discussions are given on the limitations of present TLS systems, that open new horizons for future progress of this technique, which has already found place among routine techniques for chemical analysis. In the last part, proposals for the future development of TLS toward advanced applications in new research fields are presented.
Najdeno v: ključnih besedah
Povzetek najdenega: ...high sample throughput environmental, chemical and biomedical analysis, particularly in micro space, are presented. Discussions...
Ključne besede: Thermal lens spectrometry, Microfluidic chip, Chemical analysis, Environmental monitoring, Biomedical assay
Objavljeno: 17.05.2016; Ogledov: 1570; Prenosov: 0
.pdf Polno besedilo (404,46 KB)

3.
Encapsulation efficiency of CdSe/ZnS quantum dots by liposomes determined by thermal lens microscopy
Dorota Korte Kobylinska, Jessica Batalla, Humberto Cabrera, Eduardo San Martín-Martínez, Antonio Calderón, Ernesto Marín Moares, 2015, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...thermal lensing, medical imaging, biological imaging, cell analysis, ...
Ključne besede: microscopy, imaging systems, thermal lensing, medical imaging, biological imaging, cell analysis
Objavljeno: 17.05.2016; Ogledov: 1238; Prenosov: 35
URL Polno besedilo (0,00 KB)

4.
NOVEL METHODS FOR DETECTION AND REMOVAL OF POLLUTANTS FROM WATERS
Franja Prosenc, 2017, doktorska disertacija

Opis: Water security and quality are a global issue of concern, which have recently become alarming due to the growth of the human population, industrialisation and expanded agricultural activities. Biologically active compounds, such as pharmaceuticals and personal care products can have major adverse effects on aquatic organisms, and are therefore one of the biggest threats in water quality. Another major concern is the spread of waterborne pathogens, including multidrug resistant (MDR) bacteria, which can cause serious illnesses in humans. In order to maintain water abundance and quality, it is necessary that adequate wastewater treatment and analytical techniques allowing for sensitive and fast-response detection of water hazards are in place. Conventional (waste)water treatment technologies often fail to adequately remove all of the water hazards detailed above. Moreover, conventional analytical techniques currently used in water quality control are, although highly selective and sensitive, time-extensive, with throughput of merely 2 to 3 samples per hour, excluding the time for sample preparation. With respect to these drawbacks, research was proposed to explore new approaches for degradation of recalcitrant compounds, inactivation of microorganisms, and fast screening methods, which are listed in the second chapter of this dissertation as research objectives. In the third chapter, an extensive theoretical background on the hazards found in aquatic environment, namely pharmaceuticals and waterborne pathogens, is given. Pharmaceuticals enter the environment through several routes (disposal of unused medication via the toilet, pharmaceuticals passing through the human body unchanged/slightly transformed, animal excretions of pharmaceutically active compounds, insufficient wastewater treatment, etc.); therefore, traces of pharmaceuticals have repeatedly been reported in surface waters, groundwater, wastewater effluents, and even drinking water. Iodinated contrast agents (ICAs), as the compounds of interest in this project are further described. ICAs are eliminated from the human body practically unchanged; therefore a large proportion of them end up in municipal and hospital wastewater, where they can be present in concentrations of up to 2.4 g/L. Their ecotoxicity, degradation attempts, as well as detection monitoring in the environment are reviewed within the chapter. Additionally, waterborne pathogens, which account for 2.2 million deaths per year, are reviewed in this chapter, with emphasis on multidrug-resistant (MDR) bacteria. Although MDR infections are mostly prevalent in hospital environments, the presence of MDR bacteria in the environment is not a rarity. A high percentage of bacterial isolates in waters have been shown to be of an MDR phenotype. The theoretical background in analytical methods in water quality monitoring is also given in this chapter. Vanguard and rearguard techniques are explained, the first offering simple, cheap, and rapid sample screening, but sacrificing sensitivity and selectivity, whereas the second providing the highest quality information, excellent sensitivity and selectivity, but in expense of complicated and timely sample handling and high-cost instruments. By combining the two techniques the benefits of both can be exploited in a single system. The basic principles of thermal lens spectrometry (TLS) and its miniaturised version - the thermal lens microscopy (TLM) as fast screening methods providing high sensitivity are further explained, and their practical applications are reviewed. Furthermore, composite materials have recently been finding applications in water treatment technologies, as filter materials, adsorptives for pollutants, catalysts for degradation reactions, and disinfectants. The applications of three main types of composites: synthetic composites, biocomposites, and nanocomposites, are also reviewed within this chapter. The core of this dissertation is presented in the fourth and the fifth chapter, which examine two separate approaches for water treatment, as well as analytical methods for fast screening purposes. The fourth chapter is investigating options for degradation of iodinated X-ray agents (ICAs), namely diatrizoate, through biodegradation with extracellular enzymes of white rot fungus Dichomitus squalens, and chemical oxidation with manganese(III) acetate. Enzymatic degradation with laccase (Lac) and manganese peroxidase (MnP) at low enzymatic activities was unsuccessful, whereas at approximately 3-times higher activities the enzymes were capable of 60 % degradation in 12 days. Chemical oxidation of diatrizoate with manganese(III) acetate resulted in 85 % degradation in 12 days. Moreover, the suitability of microfluidic flow injection analysis coupled with thermal lens microscopy (μFIA-TLM) as a fast screening method for diatrizoate degradation was examined. The degradation was monitored through the release of iodide from the diatrizoate molecule. μFIA-TLM proved to be a preferable method over UV-Vis spectrophotometry, due to its higher sensitivity, sample throughput, and simple sample handling. Limit of detection (LOD) for μFIA-TLM method was estimated to be 0.14 µM in a 100 µm channel, which is 9 times lower than LOD obtained in UV-Vis measurements. In addition to μFIA-TLM and UV-VIS, high-pressure liquid chromatography (HPLC) was used to monitor the remaining parent compound in the reaction mix. In the fifth chapter, the second water treatment approach is described. This includes synthesis of biocomposite materials from cellulose (CEL) and keratin (KER), with metal (Ag0, AgCl, Au0) nanoparticles (NPs). Materials were characterised for presence, species, and size of NPs with X-ray diffraction (XRD) and with scanning electron microscopy (SEM). Nanoparticles were confirmed to be of expected species, with sizes as follows: 6.3 ± 0.5 nm for Au NPs, 12 ± 2 nm for Ag NPs, and 22 ± 1 nm for AgCl NPs. In order to evaluate antibacterial properties of the materials, contact tests with gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive bacteria (Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), and Vancomycin-resistant Enterococcus faecalis (VRE)) were conducted. Direct-contact assay over 24 hours showed a dose and species-dependent antibacterial activity of [CEL:KER + Ag NPs] materials. The highest potency against the selected bacteria (up to 6-log of reduction) was observed for the material with 500 mg of Ag NPs. AgCl NPs appeared to be less potent than Ag NPs, whereas Au NPs exhibited antibacterial activity only against MRSA and VRE. In addition, antiviral properties of materials were investigated on selected bacteriophages (MS2, phiX174, and fr). However, biocomposite materials with 500 mg of Ag NPs and AgCl NPs, as well as, 240 mg of Au NPs did not exhibit any activity against selected bacteriophages. Biocompatibility with human fibroblasts was evaluated through a direct contact assay for 3 and 7 days of exposure. High concentrations of metal NPs turned out to be cytotoxic for human fibroblasts, whereas the amount of 69 mg of Ag NPs in [CEL:KER] was low enough not to affect the viability of the fibroblasts after 3 days of exposure. Composites with Ag NPs and AgCl NPs were also tested for leachability of NPs out of the materials. Both types of NPs were leaching out in two different forms, as silver ions, and as colloidal silver. Leaching of ionic silver from both materials stabilised after 3 days, whereas colloidal silver was still leaching out on the 7th day. The overall percentage of the total silver (ionic + colloidal) leached was only 0.04 % of silver incorporated in the material. In summary, this dissertation investigates alternative approaches for water treatment technologies, which could potentially serve as unit improvements of existing technologies, or as on-point pre-treatment technologies to facilitate further conventional water treatment techniques. It also demonstrates the suitability of μFIA-TLM for fast screening measurements in aquatic samples, offering high sample throughput, simple handling of the samples and superior sensitivity over the UV-Vis spectrophotometry.
Najdeno v: ključnih besedah
Povzetek najdenega: ...a single system. The basic principles of thermal lens spectrometry (TLS) and its miniaturised version... ...Moreover, the suitability of microfluidic flow injection analysis coupled with thermal lens microscopy (μFIA-TLM) as...
Ključne besede: Antibacterial biocomposites, nanomaterials, water treatment technologies, multidrug-resistant bacteria, iodinated contrast agents, thermal lens microscopy, flow-injection analysis, microfluidics
Objavljeno: 26.04.2017; Ogledov: 1883; Prenosov: 44
.pdf Polno besedilo (27,08 MB)

5.
6.
Amorphous nanocomposite of polycarbosilanes and aluminum oxide
Andraž Mavrič, 2018, doktorska disertacija

Opis: This work presents a paradigm for high temperature stabilization of bulk amorphous aluminium oxide. The thermodynamic stabilization is achieved by preparing a nanocomposite, where polymethylsilane dendritic molecules are dispersed in an aluminium hydroxide gel. Upon heat-treatment the gel transforms to the amorphous aluminium oxide that is stable up to 900°C. The dispersion of the macromolecules and their covalent bonding to the alumina matrix induce homogeneously distributed strain fields that keep the alumina amorphous. The first part of the thesis focuses on the synthesis, characterization and solubility properties of the dendritic polymethylsilane. The polymethylsilane is synthetized by electrochemical polymerization from trichloromethylsilane monomer. The polymerization mechanism, involving a single polymerization pathway, is identified. The polymer growth proceeds through reduction of the monomers to the silyl anions and their addition to the growing polymer. The solubility of three chemically related but topologically different polysilanes (linear, dendritic and network) were studied by dynamic light scattering. At room temperature the agglomerates in a range from 500 to 1300 nm are present. They undergo de-agglomeration at slightly elevated temperatures of around 40°C. The de-agglomeration results in formation of stable solutions, where a hydrodynamic diameter of the individual polymer molecules was measured to be in a range from 20 to 40 nm. The obtained diameters of two dendritic polymethylsilane macromolecules, synthesized under different electrolysis conditions, are much larger than the theoretical size estimated for an ideal dendrimer. We determined by 29Si NMR that the reason for this is in a large number of branching irregularities (defects) contained in the molecular structure. Combining the experimental values obtained by DLS and density measurements with a structural model that considers the branching irregularities, it is shown that the inclusion of the defects allows the dendritic polymer to exceed the sterical limitations and form the hyperbranched dendritic structure. The final size depends on a relative amount of the branching defects. In the second part, the synthetized polymethylsilane molecules were successfully used for the nanocomposite formation. The aluminium hydroxide gel with the dispersed polymethylsilane molecules was prepared as a precursor. Upon heat-treatment it gives the amorphous aluminium oxide stable up to 900°C. The dispersed macromolecules induce homogeneously distributed strain fields that keep the aluminium oxide amorphous during the thermal treatment the dispersed macromolecules covalently bind to the matrix, inducing the interface strain. The amorphous state was confirmed by the presence of penta-coordinated aluminium detected by 27Al NMR and a low bandgap measured by UV-vis absorption spectroscopy.
Najdeno v: ključnih besedah
Povzetek najdenega: ...keep the aluminium oxide amorphous during the thermal treatment the dispersed macromolecules covalently bind to... ...hyperbranched dendritic structure, dynamic light scattering, thermal analysis, transmission electron microscopy, scanning electron microscopy, X-ray...
Ključne besede: amorphous aluminium oxide, polymethylsilane, nanocomposite, electropolymerization, solubility, agglomeration, de-agglomeration, dendrimer, hyperbranched dendritic structure, dynamic light scattering, thermal analysis, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, infrared spectroscopy, UV-Vis spectroscopy
Objavljeno: 19.07.2018; Ogledov: 1059; Prenosov: 65
.pdf Polno besedilo (5,07 MB)

7.
Rapid and Sensitive Determination of ChE Activity in Blood Plasma
Andrej Jerkič, Tjaša Birsa, Mojca Žorž, Dorota Korte, Martina Bergant Marušič, Mladen Franko, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...flow injection analysis, thermal lens spectrometric detection, acetylcholinesterase, butyrylcholinesterase, enzy... ...flow injection analysis,thermal lens spectrometric detection, acetylcholinesterase, butyrylcholinesterase, enzy...
Ključne besede: flow injection analysis, thermal lens spectrometric detection, acetylcholinesterase, butyrylcholinesterase, enzyme activity
Objavljeno: 16.07.2018; Ogledov: 580; Prenosov: 0
.pdf Polno besedilo (642,94 KB)

8.
TLS-FIA System For Screening of Dissolved Iron in Ocean Water
Gaja Tomsič, Dorota Korte, Arne Bratkič, Mladen Franko, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...flow injection analysis, iron concentration, ocean water, thermal lens spectroscopy...
Ključne besede: flow injection analysis, iron concentration, ocean water, thermal lens spectroscopy
Objavljeno: 16.07.2018; Ogledov: 667; Prenosov: 0
.pdf Polno besedilo (679,78 KB)

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