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1.
BIOAEROGELS: PROMISING MATERIALS FOR IMPREGNATION OF DRUGS : diploma thesis dissertation
Jorge Rodríguez Antolín, 2020, undergraduate thesis

Abstract: The following work examines the possibility of impregnating chosen model drug into bioaerogels to obtain final formulation with added value. The drug used in this study was esomeprazole, used to treat acid-related diseases. In the first part of the work, bioaerogels were prepared. Polysaccharide aerogels are lightweight biocompatible and biodegradable materials, suitable for applications in pharmaceutical industry. For this purpose, three different cores were prepared: pectin, alginate and their mixture, followed by coating with chitosan layer. The production of the bioaerogels follows a sol-gel synthesis and supercritical drying technique. All samples were characterised, and optimisation was performed based on examined properties. Aerogels having a pectin core and chitosan coating showed the highest surface area and the highest adsorption capacity. In the second part, the impregnation of esomeprazole was performed using two different methods: supercritical impregnation and diffusion via sol-gel synthesis. For supercritical impregnation, supercritical carbon dioxide was used as a solvent for impregnation of the drug. In the diffusion method, the model drug was added during sol-gel synthesis using ethanol as solvent. Finally, complete characterisation of prepared formulation followed by drug release studies was performed. The study showed successful impregnation of esomeprazole using either carbon dioxide or ethanol as a solvent. Bioaerogels proved to be promising as carriers for achieving the optimal release of the chosen drug.
Keywords: Bioaerogels, polysaccharides, supercritical impregnation, diffusion method, esomeprazole
Published in DKUM: 09.07.2020; Views: 525; Downloads: 41
.pdf Full text (1,28 MB)

2.
Characters of innovation management in the primary health care centers
Alireza Aslani, Marja Naaranoja, 2013, original scientific article

Abstract: Innovation management in the primary health care centers is one of the important debates among the governments and academic forums. Although the number of studies in the field of innovation in health care sectors has increased over the last 10 years, little is known about the conditions for the successful implementation of innovations in the health care centers. In this paper, we review and assess the situation of Finnish health care centers from innovation management viewpoint. We try to answer one of the important questions designed by policy makers: “How can Finnish health care centers move toward systems that continuously improve their innovation and creativity?” The presented framework describes the main characters and dimensions of diffusion of ideation and innovation in the health care centers.
Keywords: health care centers, ideation, diffusion of creativity and innovation, Finland
Published in DKUM: 29.11.2017; Views: 784; Downloads: 360
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3.
Organizational innovation in health care - as a process
Matjaž Mulej, Tatjana Mlakar, 2008, review article

Abstract: Slovenia, like most countries of the modern world, spends too much on its public health care and supplies too little public health care services for the government, economists, politicians, and citizens to be happy. The many reforms of the public health care, e.g. in Slovenia, seem to be inefficient, one after the other, in solving this problem. Reforms have been conceived with a too poor consideration of the law of the requisite holism in decision preparation, decisions making and decision implementation. The article tackles procedure of implementation of reforms as inventions are supposed to become innovations in the public health care organization and management, rather than reforms' content. Combination of the absorption capacity, innovation promotion and diffusion is suggested for the requisite holism of implementation.
Keywords: dialectical system, diffusion of novelties, government, innovation, the public health care, requisite holism, systems thinking
Published in DKUM: 07.08.2017; Views: 968; Downloads: 91
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4.
Comparing algebraic and numerical solutions of classical diffusion process equations in computational financial mathematics
Andreas Ruffing, Patrick Windpassinger, Stefan Panig, 2001, original scientific article

Abstract: We revise the interrelations between the classical Black Scholes equation, the diffusion equation and Burgers equation. Some of the algebraic properties the diffusion equation shows are elaborated and qualitatively presented. The related numerical elementary recipes are briefly elucidated in context of the diffusion equation. The quality of the approximations to the exact solutions is compared throughout the visualizations. The article mainly is based on the pedagogical style of the presentations to the Novacella Easter School 2000 on Financial Mathematics.
Keywords: diffusion processes, diffusion equations
Published in DKUM: 14.06.2017; Views: 653; Downloads: 335
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5.
Finite size effects in soft matter under an electric field stimulus
Saša Harkai, 2016, master's thesis

Abstract: In this thesis, we study the effect of an external electric field on the properties of glass forming liquids. We present the properties relevant and important for understanding the phenomenon, such as the transition temperature and the temperature dependence of viscosity. We create a numerical model and use a method called molecular dynamics with the Lennard-Jones potential and an added external field as the interatomic potential to simulate molecular motion within a glass forming liquid. We implement analysis methods to calculate properties such as the radial distribution function, static structure factor, diffusion coefficient, non-Gaussian parameter, and relaxation time. We use the implemented methods to evaluate the molecular behaviour of the simulation and compare the results with theoretical predictions.
Keywords: finite size, glass transition, diffusion constant, dynamic heterogeneity, electric field
Published in DKUM: 21.09.2016; Views: 1065; Downloads: 106
.pdf Full text (1,38 MB)

6.
7.
“Thermodynamic and physical properties for high pressure process design”
Maša Knez Marevci, 2014, doctoral dissertation

Abstract: The thesis is comprised of three main categories. The first part of dissertation covers investigations of phase equilibria of compounds from natural materials in conventional and also non conventional supercritical fluids. In details, the impact of pressure and/or temperature on the system behaviour (miscibility, solubility, phase inversion) is investigated, quantitative and qualitative analyses to evaluate and identify compounds contained after performing preliminary extraction experiments from different natural tissues are presented. The impact of operating parameters (pre-treatment of the raw material with SFE; different extraction solvents: propane, CO2, non conventional SCFs; different extraction temperatures and pressures) on extraction kinetics is observed. Following substances were taken into consideration: vanillins, caffeine, carnosoic acid extract and lecithin. Second part of dissertation covers studies of phase equilibria of the systems bio oil/gas, which is crucial in biorefinery process design. In this part of dissertation, which covers studies of phase equilibria of binary and ternary systems, the impact of pressure and/or temperature on the system behaviour (miscibility, solubility, phase inversion) for binary system bio oil/supercritical fluid (bio oil/CO2) and (bio oil/H2) was studied. Additionally, phase behaviour of ternary systems of (bio oil/diesel/CO2) and (bio oil/tail water/CO2) under the impact of pressure and/or temperature is observed. These data are of a high importance for bio refineries as an important part of necessary sustainable development. In recent years, studies on biodiesel synthesis have focused on development of process intensification technologies to resolve some of these issues. Fundamental data to design fractionation process of components of bio oil are crucial for an efficient hydrogenation process of bio oil. In the third part of dissertation observation of phase equilibria and determination of the parameters like diffusion coefficient, density and viscosity for the systems polymer/CO2 at elevated pressures is investigated. An overview of different methods applied to determine the parameters like diffusion coefficient, density and viscosity of the systems polymer (PEG)/CO2 at elevated pressures is offered. Observation of phase equilibria of the binary system PEG/CO2, determination of the impact of pressure and/or temperature on the system behaviour (miscibility, solubility, phase inversion), determination of thermodynamically and physically properties of the system with new applicative methods and finally, comparison of the results obtained by different methods is provided. The interfacial tension (IFT) at the (PEG)/CO2 interface has been determined by using an experimental technique developed to study the interfacial interactions of the liquids in equilibrium with gas in a glass-windowed equilibrium cell by the means of Capillary Rise (CR) method. Advantages and disadvantages of methods that were applied are exposed and discussed.
Keywords: phase equilibria, natural materials, conventional and non conventional supercritical fluids, extraction, bio oil, data for biorefinery process design, systems polymer (PEG)/CO2, diffusion coefficient, density, viscosity, surface tension, Capillary Rise (CR) method.
Published in DKUM: 28.10.2014; Views: 2245; Downloads: 300
.pdf Full text (4,46 MB)

8.
APPLYING THE GRAIN-BOUNDARY DIFFUSION PROCESS USING ELECTROPHORETIC DEPOSITION TO SELECTED REGIONS OF A Nd-Fe-B MAGNET
Blaž Goričar, 2014, master's thesis

Abstract: This Master's thesis research is about the localized coercivity enhancement of Nd-Fe-B magnets, which are used in electric motors. Computer simulations show, that when magnets operate at high temperatures, they experience large demagnetizing fields. However, this happens only on specific parts of the body of the magnet. The demagnetization can be prevented by locally enhancing the coercivity only on these specific parts. The goal of this Master’s thesis was to research the localized coercivity enhancement by creating a magnet, where one half would have different magnetic properties compared to the other half. Commercially available Nd-Fe-B magnets were bought from Shin-Etsu, Japan. The magnetic properties of the magnets were measured on two very different devices – the permeameter and the vibrating sample magnetometer. The demagnetization curves were compared. The coercivity of the magnet was improved with the electrophoretic deposition of dysprosium on the surface. The dysprosium then diffused, at high temperature, from the surface to the inside of the magnet along the grain boundaries. The microstructure of the magnet was analysed on the scanning electron microscope, while the content of the elements was quantitatively analysed with the EDS method. The demagnetization curves of both devices were comparable. The grain-boundary diffusion process of dysprosium with the electrophoretic deposition increased the coercivity of the magnet by 25 %, without any significant loss in remanence. The research on the localized grain-boundary diffusion was first done with measurements on the vibrating sample magnetometer and then confirmed with the Hall probe. We discovered that one part of the magnet could have different magnetic properties compared to the other half. There was a clear border between the two.
Keywords: Nd-Fe-B magnet, coercivity, magnetic properties, electrophoretic deposition, grain-boundary diffusion process.
Published in DKUM: 09.09.2014; Views: 1964; Downloads: 116
.pdf Full text (4,38 MB)

9.
Antimicrobial medical textiles based on chitosan nanoparticles for gynaecological treatment
Tijana Ristić, 2014, doctoral dissertation

Abstract: The aim of this dissertation was to develop a novel medical tampon for alternative gynaecological treatment using chitosan nanoparticles as an antimicrobial agent or as a drug delivery system. For this purpose viscose tampon band was used and functionalized with chitosan and trimethyl chitosan nanoparticles. A comprehensive of interactions between chitosan and cellulose as well as characterization of prepared materials were done. At the beginning, chitosan (CS) and trimethyl chitosan (TMC) solutions, as well as nanoparticles synthesised by ionic gelation were studied. Their characterization was focused on determining the charge and antimicrobial properties against common pathogenic microorganism. The influence of cationic charge on the inhibition of microbial growth was confirmed. Since CS and TMC solutions and nanoparticles dispersions exhibited antibacterial activity against Lactobacillus, a detailed investigation in chitosan’s antimicrobial mode of action was performed using a novel diffusion nuclear magnetic resonance (D-NMR). D-NMR allowed the monitoring of intra- and extracellular water exchange from the cells indicating the membrane alteration and leakage of intracellular constituencies. Further, in order to study the adsorption phenomena and molecular interactions between CS/TMC (solution or nanoparticles) and cellulose material, model cellulose surfaces were used, and adsorption was studied by quartz crystal microbalance with dissipation. CS and TMC were favourably deposited onto cellulose model surface at higher ionic strength, higher pH values, i.e. factors causing lower solubility, where the presence of electrostatic interactions was negligible and non-electrostatic interactions were dominant. The knowledge gained from the model surfaces was extremely helpful in characterization of real systems, i.e. functionalized cellulose fibres and for understanding the obtained results. Immobilization of CS and TMC (in the form of solution and/or nanoparticles) onto cellulose viscose fibres was confirmed with several analytical methods. The attachment of chitosan onto fibres was reversible, as endorsed with desorption studies mimicking the conditions of vaginal usage. Evaluation of antimicrobial properties was performed using two different techniques, both revealing a high inhibition of the tested microorganism. In addition, Lactobacillus susceptibility testing has shown that chitosan-coated fibres do not have any negative influence on the resident microbiota. Assessment of in-vitro cytotoxicity demonstrated that samples do not cause a cytotoxic effect in direct contact. Additionally, model drug was incorporated into chitosan nanoparticles and subsequently attached onto fibres in order to create modern, vaginal drug delivery systems. Antimicrobial medical textiles investigated in the scope of this dissertation show the potential for their exploitation in gynaecological field as preventive or curative treatment without triggering any adverse effects for the user.
Keywords: chitosan, N, N, N-trimethyl chitosan, nanoparticles, antimicrobial activity, cellulose model films, regenerated cellulose fibres, diffusion nuclear magnetic resonance, quartz crystal microbalance, vaginal infections, drug delivery systems, cytotoxicity
Published in DKUM: 13.02.2014; Views: 3041; Downloads: 137
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10.
Modelling airport congestion charges
Milan Janić, 2005, original scientific article

Abstract: This article deals with modelling congestion charges at an airport. In this context, congestion charging represents internalizing the cost of marginal delays that a flight imposes on other flights due to congestion. The modelling includes estimating congestion and flight delays, the cost of these delays and the efficiency of particular flights following the introduction ofa congestion charge. The models are applied to an airport / New York LaGuardia / to illustrate their ability to handle more realistic congestion scenarios as well as the nature of the congestion to be charged, the effectiveness of the congestion charge and a sensitivity analysis based on changes in the nature of congestion as well as characteristics of demand in terms of flight-aircraft type and airport capacity.
Keywords: airport, congestion charging, queueing theory, diffusion approximation, New York LaGuardia airport
Published in DKUM: 05.06.2012; Views: 1397; Downloads: 194
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