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Biological synthesis of silver nanoparticles
Kubínová, Martina ; Španová, Alena (referee) ; Rittich, Bohuslav (advisor)
Silver nanoparticles and its potencial use and influence on the environment is still object of research. Methodics of synthesis of silver nanoparticles is already well investigated and study deals with more economical ways of syntesis by metireals, which are environmentally friendly and nontoxic. Biochemical production of nanoparticles has both advantages. This study focused on the production of nanoparticles by lactic acid bacteria and antibacterial activity. Experimental part of the study focused on amplification DNA isolated from Lactobacillus gasseri K7, which has efficiency to form silver nanoparticles. DNA was isolated in PCR, it was confirmed using primers specific for domena Bacteria and species Lactobacillus gasseri.
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Preparation and properties of silver nanoparticles on collagen matrix
Konečná, Zuzana ; Chamradová, Ivana (referee) ; Vojtová, Lucy (advisor)
Cílem předložené diplomové práce byla in-situ příprava stříbrných nanočástic na kolagenové matrici jako antibakteriálního povlaku a studie vlivu podmínek přípravy na vlastnosti nanočástic, zejména jejich velikost, tvar, homogenita jejich distribuce a antibakteriální aktivita. V rámci práce byla rovněž sledována kinetika redukce stříbrných nanočástic z dusičnanu stříbrného a vliv teploty na její průběh. Připravený materiál a jeho vlastnosti byly analyzovány pomocí různých technik. UV-VIS absorpčních vlastností stříbra bylo využito pro kinetické studie redukce a uvolňování nanočástic. Pomocí rastrovací elektronové mikroskopie byla vyhodnocena homogenita stříbrného povlaku a přibližná velikost částic a jejich aglomerátů. Velikostní distribuce nanočástic byla pak přesně stanovena pomocí dynamického rozptylu světla. Pomocí infračervené spektrometrie s Fourierovou transformací s technikou úplného zeslabeného odrazu byla sledována interakce stříbra s funkčními, zejména karboxylovými skupinami. Termogravimetricky byla stanovena tepelná stabilita a procentuální obsah stříbra v materiálu. Vliv AgNPs povlaku na 3D strukturu kolagenního scaffoldu a fázový kontrast pro 3D zobrazovací techniky byl zkoumán pomocí rentgenové výpočetní nanotomografie. V neposlední řadě byla také stanovena antibakteriální aktivita připraveného materiálu a její závislost na koncentraci stříbra.
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THE APPLICATION OF NANOMATERIALS FOR LEAD FREE SOLDERS DEVELOPMENT
Pešina, Zbyněk ; Pinkas, Jiří (referee) ; Spousta, Jiří (referee) ; Sopoušek, Jiří (advisor)
The present dissertation is motivated by the search for alternatives of lead-free soldering by nanoparticles of metals and their alloys. The research focuses on the possibility of replacing lead-free solders by nanoparticles. This issue is currently being addressed by the use of lead-free solders but their properties are not entirely equivalent to properties of lead-tin based alloys. The theoretical part of the dissertation first summarizes up-to date knowledge on the development of lead-free alloys currently used for soldering in the electronics. The work compares these lead-free solder candidates with previously used Pb-Sn alloys. The second section of the theoretical part is devoted to nanotechnology that offers possible solutions of problems associated with the use of lead-free solders. The text contains a description of the properties of nanocrystalline materials in comparison with those of compact alloys having the same chemical composition. The possibility of preparation of nanoparticles and potential problems associated with small particle sizes are also presented. Introduction of the experimental part focuses on the preparation of nanoparticles of pure metals and alloys by chemical and physical ways as well as on an instrumentation for characterisation and analysis. Attention is focused on the silver in nanoparticle form that exhibits the low temperature sintering effect, which is thermally activated by decomposition of oxide envelope covering the Ag nanoparticles. This factor is critical for low-temperature sintering and thus also for possible future applications. The thermal effects of the low sintering process were studied by methods of thermal analysis. The preparation of the Cu / Ag nano / Cu joints was carried out in-situ in inert atmosphere and under the action of atmospheric oxygen. In both cases varying conditions of thermal treatment were used. The cross sections of the prepared joints were then used for the metallographic analysis of the local mechanical properties of the resulting silver layer, for the chemical composition evaluation of the resulting layers of the joint, and for the microstructure study. Strength characteristics are represented by testing shear strength of individual joints.
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Application of plasmonics in organic photovoltaics
Láska, Martin ; Fejfar, Antonín (referee) ; Šikola, Tomáš (advisor)
Tato diplomová práce se zabývá studiem plasmonicky navýšené absorpce vedoucí ke zlepšení účinnosti organických solárních článků. K navýšení absorpce světla ve fotoaktivní vrstvě jsou použity koloidní nanočástice stříbra. Rozptyl světla z nanočástic střibra do fotoaktivní vrstvy představuje jedno z možných řešení, jak navýšit celkovou účinnost fotovoltaických zařízení. Simulace elektromagnetických jevů jsou pro statické podmínky prováděny v softwaru Lumerical (Lumerical Solutions, Inc.). Je zkoumána absorpce ve fotoaktivní vrstvě v závislosti na konfiguraci stříbrných nanočástic. Simulace potvrzují, že ve fotoaktivní vrstvě, která je modifikovaná nanočásticemi stříbra, dochází k navýšení absorpce. Abychom potvrdili výsledky simulací, bylo vyrobeno několik stříbrem modifikovaných vzorků. Vzorky byly pro tento druh experimentu připravené z poly(3-hexyltiofenu):[6,6]-fenyl-C61-butyric-acid-metyl esteru. U některých, nanočásticemi stříbra modifikovaných, vzorků dochází k navýšení tvorby excitonů, v důsledku čehož je pozorován nárůst fotoproudu. V této práci je zahrnut teoretický i experimentální přístup k dané problematice.
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Identification and characterisation of selected properties of some strains of lactic acid bacteria
Sásková, Denisa ; Horák, Daniel (referee) ; Rittich, Bohuslav (advisor)
Nanotechnology is currently one of the fastest growing scientific disciplines. An interesting area of research is the biosynthesis of metal nanoparticles using microorganisms including lactic acid bacteria. In the first part this diploma thesis focuses on verification of identity of bacterial species Lactobacillus casei and Lactobacillus paracasei by genus- and species-specific PCR. In the next part of experimental work the capability of six Lactobacillus strains to produce silver nanoparticles is tested. Synthesis of nanoparticles was confirmed for all the strains depending on the amount of added AgNO3 and on time of cultivation. Differences between the strains were detected.
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Electroless selective deposition of silver nanoparticles
Salajková, Zita ; Bartoš, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
Silver nanoparticles have a widespread use in the field of plasmonics. Since deposition of nanoparticles from colloidal solutions onto an exact location on a substrate is difficult, it seems advantageous to grow the nanoparticles in-situ. The presented work is focussed at selective deposition of~silver nanoparticles from colloidal solution or from solution reach of silver ions under assistance of focussed electron beams. Successful deposition could lead to growth of well defined nanostructures directly at the substrate surface. The effect of electron beam intensity to surface quality is studied (silica reduction, surface morphology) as well as effect of pH to particle properties. Outputs are used as a part in theoretical description of selective deposition and confirmed by following advanced experiments. The light assisted deposition and growth of nanostructures is described at the end of the presented work.
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Enhancement of detection limits in Laser-Induced Breakdown Spectroscopy (LIBS) using nanoparticles
Képeš, Erik ; Prochazka, David (referee) ; Sládková, Lucia (advisor)
This bachelor's thesis describes the options of ehnancing the detection limits of laser-induced breakdown spectroscopy (LIBS). It summarizes different modifications of the classical LIBS apparatus, which are used by methods double-pulsed LIBS (DPLIBS), Townsend effect plasma sectroscopy (TEPS), resonance enhanced LIBS (RELIBS), spark discharge LIBS (SDLIBS), flame-enhanced LIBS (FELIBS), and new ways of sample preparation, such as are used in the method nanoparticle enhanced LIBS (NELIBS). It briefly describes the mechanisms, which are used by each method to reduce the detection limit and it contains an overview of obtained enhancements against the classical method LIBS. It deals with the method nanoparticle enhanced LIBS in more detail and experimentally verifies and studies the effects of nanoparticles of different types and sizes on the emission spectrum of the method LIBS.
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Preparation of gold, silver and platinum colloid solutions by precursors decomposition in low temperature plasma
Brožek, Vlastimil ; Kutílek, Zdeněk ; Mastný, L. ; Sýkora, V. ; Benešová, L. ; Sofer, Z.
Liquid precursor decomposition in the low temperature plasma generated by WSP® was used for synthesis of precious metals nanoparticles. The gold in the form of H[AuCl4], silver in the form of AgNO3 and platinum in the form of H2[PtCl6] were used to generate colloid solutions with concentration of 5 mg.l-1 – 70 mg.l-1 and particle size of 20 nm – 120 nm. The solution contained elevated concentration of nitrite and nitrate ions due to the reaction of plasma with nitrogen form air. In order to reduce the concentration of nitrite and nitrate ions the plasma generated nanoparticles was projected by plasma torch to the ammonium chloride solution. Other way used for reduction of NO3- and NO2- concentration was optimization of geometry of plasma system. The other way was also by application of shrouding effect by nitrogen and ammonia gas. The size of nanoparticles and their concentration can be influenced by geometry of plasma torch, composition of carrier gas and by geometry of
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SILVER NANOPARTICLES AND THEIR BACTERICIDAL EFFECT
Piksová, K. ; Weiserová, Marie ; Jedličková, A. ; Fojtík, A.
Rapid development of bio-nanotechnology lead to the new way in the combating of bacteria and to searching specific properties of nanomaterials The study of bactericidal nanomaterials is particularly timely considering the recent increase of new resistant strains of bacteria to the most potent antibiotics The present work studies the bactericidal effect of silver nanoparticles in the range of 10-30 nm on Gram-negative bacteria and Gram-positive bacteria
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