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Influence of reduction agent on granulometric parameters of silver nanoparticles
Vojtková, Katarína ; Dittrich, Milan (advisor) ; Berka, Pavel (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Candidate: Katarína Vojtková Supervisor: Doc.RNDr. Milan Dittrich, CSc. Title of diploma thesis: Influence of reduction agent on granulometric parameters of silver nanoparticles The aim of this work is to test the influence of different technological parameters on the production of silver nanoparticles. The method used along the experiments was the Tollens reduction method. As reduction agents, there were used various monosaccharides, mainly glucose, oligosaccharides, maltose, lactose and branched polysaccharide Litesse® Ultra in different concentrations. There were used mixtures of two reducing agents as well as addition of surfactants. The concentration of silver reducing ions was increased also. The work contains comparison of the effects of different concentrations of the reducing agents used and also comparison of any changes of the conditions used for the preparation samples (e.g. freezing). Both phases of nucleation and growth were modified either by microwave radiation or ultrasound irradiation. In case of the later the samples showed very small nanoparticles with an average intensity diameter of 20 nm. The outcoming results are presented in tables and pictures. The resulting products...
Heřmanová, Ivana ; Doležal, Pavel (advisor) ; Berka, Pavel (referee)
1. ABSTRACT The objective of this study is to optimize a nortryptiline hydrochloride patch previously designed (1) with the intended aim to develop controlled drug release system as a smoking cessation aid. Patches of 5%, 7.5% and 10% NTH concentrations were assayed for physical experiments. Measured thickness of the patches remains constant regardless of the NTH concentration. Obtained values are 31.88±5.0 µm, 32.33±5.1 µm and 32.00±3.8 µm for 5%, 7.5% and 10% patch respectively. The variability is lower than 20 % in every case. Release and penetration studies were performed using Franz type of diffusion cells. The maximum cumulative amount released from assayed patches at 7 hours (last sampling point) varies as a function of the NTH concentration. Two kinetic models, power law and first order kinetics, are useful in order to predict the maximum amount to be released and the rate at which the process will be developed. Taking first order results into account, the maximum amount to be released (Qinf) is 7.185±0.30[mg/cm2 ]; 12.359±0.69[mg/cm2 ]; and 29.333 ±1.97 [mg/cm2 ] for 5%; 7.5% and 10%patch respectively. Considering the power law fitting, the main conclusion is that the release mechanism is basically fickian diffusion as the exponent is about 0.5. Estimated permeation parameters are Kp=0.019·10-3...
Rheological properties of branched polyesters plasticized with triacetin
Zaoralová, Ester ; Šnejdrová, Eva (advisor) ; Berka, Pavel (referee)
Charles University of Prague Faculty of Pharmacy in Hradec Králové Pharmaceutical Technology Academic year: 2011/2012 Author: Ester Zaoralová Study program: Pharmacy Supervisor: PharmDr. Eva Šnejdrová Ph.D. Title of diploma thesis: Rheological properties of branched polyesters plasticized with triacetin. This master thesis studies rheological behaviour of the polyesters of glycolic acid and lactic acid branched with tripentaerythritol and plasticized with triacetin. The theoretical part summarizes basic rheological facts, mentions main type of the viscometers and deals with importance of the rheological testing in the drug formulation. There are described properties and application of polyesters, polycarbophil and carbomers in the pharmaceutical technology. Plasticized polyesters with various concentrations of triacetin were prepared (20 %, 30 %, 40 %), their viscosity was measured by Brookfield viscometer at 37 and 50 řC. To compare, viscosity of the aqueous dispersion of polycarbophil, carbomers and acacia gum was measured too. Flow behaviour was evaluated by the viscosity curves. The rheological behaviour of plasticized polyesters was influenced particularly by plasticizer concentration, as well their molar weight and branched ratio. Interactions between polyester chains were significantly...
Nanofibre medicated membranes 8.
Kučerová, Iveta ; Doležal, Pavel (advisor) ; Berka, Pavel (referee)
Thesis in theoretical part provides an overview of oral drugs in the biopharmaceutical point of view. It describes the main difficulties of this application route and presents selected facts about new approaches to improve the bioavailability of poorly absorbable substances. These approaches, in recent years, also use nanofiber membranes. The experimental part focuses on the in vitro evaluation of diamine delivery from nanofiber membranes in vehicle buffered at pH 7.4. The tested membranes contain the active substance in three graduated concentrations (20%, 30% and 40%), and specifically differ in basic weight. To evaluate the delivery the fluxes of diamine witin the first linear section of delivery are used, the percentage of substance released within 60 minutes was used to the evaluation of releasable proportion of diamine. Determination of diamine was performed by HPLC. The release of nearly all releasable diamine amounts were always obtained in 15 minutes from the beginning of release. The release rate of the diamine from nanofiber membranes is high. Important, however, is the finding that the rate of drug release is not probably significantly dependent on the drug concentration in the nanofiber membrane, but it is significantly influenced by the basic weight of membranes. The variability...
Nanoparticles and their utilization for nanoviscosity measurement in colloid dispersions of HPMC.
Wanková, Olga ; Berka, Pavel (advisor) ; Doležal, Pavel (referee)
Theoretical part of this thesis deals with nanoparticles, their preparation and utilization. It briefly summarizes microrheological methods, especially DLS. It de- scribes hypromellose (HPMC), its properties and utilization in pharmacy. In the experimental part of the thesis a method of dynamic light scattering (DLS) was used to assess diffusion coefficients of particles sized 20 nm, 60 nm, and 100 nm in dispersion medium of colloid solutions of HPMC. These were studied: polymers O1, O2, O3 and O4 in concentration 0,5%, 0,25%, 0,125%, 0,0625% and 0,03125%. Relative nanoviscosity ηn-rel of individual samples which was based upon values of diffusion coefficient Di measured by DLS was compared with relative macroviscosity ηrel assigned upon results measured by capillary viscosimetry. Relative nanoviscosity ηn-rel is more significant than relative macroviscosity ηrel for the behavior of polystyrene particles of used sizes in dispersion medium of colloid solutions of HPMC. Relative nanoviscosity ηn-rel is changing depending on used dispersion medium and size of nanoparticles. Key words: nanoparticles, DLS, hypromellose, relative (macro-)viscosity, relative nanoviscosity.
Permeation in vitro study of transkarbam 12 stability in oleocremes.
Nedbálková, Iva ; Doležal, Pavel (advisor) ; Berka, Pavel (referee)
The work extends the original method of biological titration with the concrete assessment of the stability of an active form of T 12 in two creams of functionally usable composition. The work compiles basic information on the skin barrier, chemically modulated penetration of drugs through the skin, especially transkarbam 12 (T 12) as an accelerator. Its influence on the permeation characteristics of caffeine as a marker is a basis of the experiment itself. The principal experimental results have been obtained by measuring of in vitro (pig skin ear samples) fluxes of caffeine dispersed always in 1% concentration in hydrophobic creams containing 0.2% and 0.4% of T 12. The average results of the pertinent fluxes were for the 0.2% cream J = 6,4 ± 2,0 in one week after manufacturing, and J = 7,2 ± 2,3 in 210 days after manufacturing. Analogical values for the 0.4% lotion were J = 6,7 ± 1, in one week after manufacturing, and J = 5,5 ± 1,2 after 165 days after manufacturing. The evaluation of these results by non-pair t-tests with the level of reliability of 0.95% has proved that the permeation characteristics of both creams (with 0.2% and 0.4% of T 12) in the scrutinized period (210 days or 165 days, respectively). It is thus possible to treat them as equal from the permeation point of view, and the...
Nanofiber membranes as carriers of drugs 3. Polyurethane, polyvinylalcohol, polycaprolactone, polyacrylonitrile.
Krejčová, Markéta ; Doležal, Pavel (advisor) ; Berka, Pavel (referee)
Diplomová práce Markéta Krejčová ABSTRACT Nanofibre membranes as carrier of drugs 3. Polyurethane, polyvinylalcohol, polycaprolaktone, polyacrylonitrile The theoretical part deals with practical use of non-woven fabric and technology of their production by electrospinning method, it also contains basic information about tested polymers mentioned bellow. The experimental part brings results of the physical characteristics of the nanofiber membranes produced by electrospinning from polyvinylalcohol, polyurethane, polyacrylonitrile and polycaprolactone. The evaluation of contact angles of water on the membranes did not show significantly different results, although the best wettability was observed on the membrane made from polyurethane. The soak test possesses surprising results in the term of inability of polymers to absorb water. The testing of tensile strength of membranes was investigated to show a possible influence of the radiation sterilization. The only membrane that displayed increased tensile strength after the radiation sterilization was made from polyurethane. The rest of membranes did not demonstrate any changes. For the measurement of tensile direction membrane made from polyurethane was also changed. Tensile was higher in the cross direction than in the longitudinal direction. Methylparaben in...
Properties of lecithin nanoemulsions with polysorbate and polyglycerols.
Drdová, Kateřina ; Doležal, Pavel (advisor) ; Berka, Pavel (referee)
Properties of lecitin based nanoemulsions containing polysorbate and polyglyceroles Nanoemulsions, one of the lipid nanodispersions, increase bioavailability of lipophilic drugs, due to their small particle size enable drug targgetting and reduce adverse effects of many drugs. Nanoemulsions are suitable for oral, parenteral, topical and transdermal administration. Essential component of each nanoemulsion is the surfactant. Surfactant has to be chosen very carefully depending on the route of administration, type of the effective substance and other excipients. Choice of surfactant and producing method determine storage stability of final product. Influence of polysorbate 80 and polyglycerol-3-oleate in concentration of 1 %, 0,5 %, 0,1 % and 0,05 % on stability during temperature cycling was observed. Samples were exposed to the temperature 40 řC for 8 hours and 5 řC for 14 hours in turns for time period of 30 days. Particle size and zeta potential were measured and macroscopical changes of samples were observed in defined time intervals. Samples containing polyglycerol as a co-surfactant have shown smaller particle size and smaller size distribution than the samples containing polysorbate. Particle size and size distribution became smaller in time, there were also more excessive macroscopical changes due to...
The study of thermotropic phase behaviour of ceramide 2 and its mixtures with cholesterol.
Voršilková, Klára ; Zbytovská, Jarmila (advisor) ; Berka, Pavel (referee)
Diploma Thesis 2007, Petra Nerudová Abstract Thermotropic behaviour of mixtures of Ceramide (NS) with cholesterol were studied by DSC method and evaluated using IR spectrum of ceramide itself. Depending on the concentration of individual components there were shifts in melting temperature of the next phase transitions. From the measurements we found the value eutectic mixtures in which the ratio of Ceramide NS / cholesterol was 5:5 after the first heating and 3:7 after second heating. It was found that hydration also affects the behaviour of thermotropic mixture.The results of IR spectra correlated with the DSC. The temperature at which the IR measurements shown changes of Ceramide (NS) structure was in a good relation with melting temperatures determined by DSC.
Measurement of nanoviscosity of polymer solutions using nanoprobes and DLS.
Melezínková, Pavla ; Berka, Pavel (advisor) ; Doležal, Pavel (referee)
Theoretical part of this work briefly reviews nanomaterials, formation of nanoparticles and their utilization in pharmacy. Further, it deals with viscosity and options for its measurement in both macro- and nanoscale and concisely describes properties and applications of hyetellose and hyprollose. Macroviscosity and nanoviscosity of colloid solutions of polymers P1, P2 and P3 in concentrations 0,03125 %, 0,0625 %, 0,125 %, 0,25 % a 0,5 % were determined in experimental part of this work. Polystyrene nanoparticles sized 20 nm, 60 nm and 100 nm were used as nanoprobes. Diffusion coefficients were measured by DLS and used for calculation of nanoviscosity. Determined nanoviscosity was compared with macroviscosity acquired by measurement using Ubbelohde capillary viscometer. It is apparent from the comparison of the obtained values of relative macroviscosity and relative nanoviscosity that movement of nanoparticles of used size in dilute dispersions of polymers P1, P2 and P3 is more substantially affected by nanoviscosity than by macroviscosity. Keywords: DLS, nanoprobes, nanoviscosity, (macro-)viscosity

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3 Berka, P.
1 Berka, Petr
1 Berka, Přemysl
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