Study of Influence Roughness Steel Substrate on Adhesion Thin Skin of Paint System

Import 05/08/2014V teoretické části bakalářské práce jsou popsány povrchové úpravy před nanesením nátěrového systému, povrch a jeho vlastnosti. Dále hodnocení drsnosti povrchu a přilnavost substrátu. V experimentální části je hodnocena přilnavost nátěrového systému k otryskaným materiálům a to dvěma způsoby, mřížkovou zkouškou a odtrhovou zkouškou. Výsledky měření jsou uvedeny v tabulkách a z výsledků experimentálních zkoušek vyplývá, že více vyhovoval substrát z litinové drti, který měl lepší přilnavost.In the theoretical part of the thesis is describes the surface treatment prior to application of the coating system, surface and its properties. Further evaluation of surface roughness and adhesion substrate. In the experimental part of the thesis is assessment of adhesion of the coating system to blasting materials in two ways, cross-cut test and tear test. The measurement results are shown in tables, and the results of experimental tests that the more suited the substrate of blast units which have a better adhesion.345 - Katedra mechanické technologievelmi dobř

Study of Influence Roughness Metal Surface on Surface Properties

Import 02/11/2016Diplomová práce se zabývá studiem vlivu drsnosti kovového povrchu na vlastnosti povrchu. V teoretické části je popsána charakteristika povrchu, povrchové úpravy kovů a koroze. Experimentální část se zabývá studiem tlakových nádob, které se skládaly ze dvou částí a to ocelové a měděné. U ocelové otryskané části je stanovena čistota, drsnost povrchu a kotvící profil. Dále vady, které se vyskytly u těchto tlakových nádob, mikrotvrdost, makrostruktura a mikrostruktura. U měděné trubky je zkoumána mikrotvrdost, mikrostruktura a v poslední řadě důvod výskytu galvanické koroze. Návrh metodiky prací a vyhodnocení provedených zkoušek jsou zpracované ve formě grafů, tabulek a fotografií.This master thesis deals Study of Influence Roughness Metal Surface on Surface Properties. The theoretical part describes the characteristics of the surface, metal coatings and corrosion. The experimental part describes the study of pressure vessels, which consists of two parts, steel and copper. For blasted steel part are determined purity, surface roughness and blasting profile. Furthermore defects that have occurred in these pressure vessels, micro-hardness, macrostructure and microstructure. For copper pipe are examined microhardness, microstructure and last reason for the occurrence of galvanic corrosion. Proposed methodology of work and evaluation of tests are presented in the form of diagrams, tables and photos.345 - Katedra mechanické technologievelmi dobř

Hydrogel Containing Anti-CD44-Labeled Microparticles, Guide Bone Tissue Formation in Osteochondral Defects in Rabbits

Hydrogels are suitable for osteochondral defect regeneration as they mimic the viscoelastic environment of cartilage. However, their biomechanical properties are not sufficient to withstand high mechanical forces. Therefore, we have prepared electrospun poly-ε-caprolactone-chitosan (PCL-chit) and poly(ethylene oxide)-chitosan (PEO-chit) nanofibers, and FTIR analysis confirmed successful blending of chitosan with other polymers. The biocompatibility of PCL-chit and PEO-chit scaffolds was tested; fibrochondrocytes and chondrocytes seeded on PCL-chit showed superior metabolic activity. The PCL-chit nanofibers were cryogenically grinded into microparticles (mean size of about 500 µm) and further modified by polyethylene glycol–biotin in order to bind the anti-CD44 antibody, a glycoprotein interacting with hyaluronic acid (PCL-chit-PEGb-antiCD44). The PCL-chit or PCL-chit-PEGb-antiCD44 microparticles were mixed with a composite gel (collagen/fibrin/platelet rich plasma) to improve its biomechanical properties. The storage modulus was higher in the composite gel with microparticles compared to fibrin. The Eloss of the composite gel and fibrin was higher than that of the composite gel with microparticles. The composite gel either with or without microparticles was further tested in vivo in a model of osteochondral defects in rabbits. PCL-chit-PEGb-antiCD44 significantly enhanced osteogenic regeneration, mainly by desmogenous ossification, but decreased chondrogenic differentiation in the defects. PCL-chit-PEGb showed a more homogeneous distribution of hyaline cartilage and enhanced hyaline cartilage differentiation

Organizace kolejové dopravy k. p. Důl Pohraniční stráž v závěru 7. pětiletky ve vztahu k otvírce nových lokalit

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Synthesis of 2‑Alkylsulfonyl-imidazoles with Three Diversity Positions from Immobilized α‑Acylamino Ketones

The synthesis of novel imidazole derivatives via immobilized α-acylamino ketones is reported in this article. The key intermediates were prepared from the Wang-piperazine resin-supported Fmoc-amino acids. After their sulfonylation with 4-nitrobenzenesulfonyl chloride (4-Nos-Cl), followed by alkylation with α-bromoketones and cleavage of Nos group, the resulting α-acylamino ketones were reacted with Fmoc-isothiocyanate. The corresponding Fmoc-thioureas were subjected to the Fmoc-cleavage and spontaneous ring-closure to imidazole scaffold. The resulting imidazole-thiones were alkylated with alkyl halides and oxidized using meta-chloroperbenzoic acid (<i>m</i>CPBA). Trifluoroacetic acid (TFA)-mediated cleavage yielded the corresponding trisubstituted 2-alkylsulfonyl imidazoles in good crude purity and acceptable overall yields. In the case of sulfides, prepared from alkyl bromides, the unexpected products brominated at the C⁴ position of the imidazole were obtained

Convenient Synthesis of Thiohydantoins, Imidazole-2-thiones and Imidazo[2,1-b]thiazol-4-iums from Polymer-Supported α-Acylamino Ketones

The preparation of 5-methylene-thiohydantoins using solid-phase synthesis is reported in this paper. After sulfonylation of immobilized Ser (t-Bu)-OH with 4-nitrobenzenesulfonyl chloride followed by alkylation with various bromoketones, the 4-Nos group was removed and the resulting polymer-supported &alpha;-acylamino ketones reacted with Fmoc-isothiocyanate. Cleavage of the Fmoc protecting group was followed by the spontaneous cyclative cleavage releasing the 5-methylene-thiohydantoin derivatives from the polymer support. Reduction with triethylsilane (TES) yielded the corresponding 5-methyl-thiohydantoins. When Fmoc-isothiocyanate was replaced with alkyl isothiocyanates, the trifluoroacetic acid (TFA) mediated cleavage from the polymer support, which was followed by the cyclization reaction and the imidazo[2,1-b]thiazol-4-iums were obtained. Their conversion in deuterated dimethylsulfoxide led to imidazole-2-thiones

Stereoselective Synthesis of Benzo[<i>e</i>][1,4]oxazino[4,3‑<i>a</i>][1,4]diazepine-6,12-diones with Two Diversity Positions

Herein, we report a stereoselective formation of tetrahydro-6<i>H</i>-benzo­[<i>e</i>]­[1,4]­oxazino­[4,3-<i>a</i>]­[1,4]­diazepine-6,12­(11<i>H</i>)-diones. Their preparation consisted in solid-phase synthesis of linear intermediates starting from polymer-supported Ser­(<i>t</i>Bu)-OH. Using various 2-nitrobenzoic acids and bromoketones, the key intermediates were obtained in five steps and subjected to trifluoroacetic acid-mediated cleavage from the resin, followed by stereoselective reduction with triethylsilane. Subsequent catalytic hydrogenation of the nitro group and cyclization yielded the target compounds with full retention of the C^12a stereocenter configuration

4‑Chloro-2-Fluoro-5-Nitrobenzoic Acid as a Possible Building Block for Solid-phase Synthesis of Various Heterocyclic Scaffolds

4-Chloro-2-fluoro-5-nitrobenzoic acid is a commercially available multireactive building block that can serve as a starting material in heterocyclic oriented synthesis (HOS) leading to various condensed nitrogenous cycles. This work describes its ability for the preparation of substituted nitrogenous heterocycles having 5–7-membered cycles via polymer-supported <i>o</i>-phenylendiamines. Immobilization of this compound on Rink resin followed by further chlorine substitution, reduction of a nitro group and appropriate cyclization afforded benzimidazoles, benzotriazoles, quinoxalinones, benzodiazepinediones and succinimides. The method developed is suitable for the synthesis of diverse libraries including the mentioned types of heterocycles, which have significant importance in current drug discovery. In this paper, we also report limitation of these method and unsuccessful attempt to prepare an 8-membered benzodiazocine cycle

Solid-Phase Synthesis of Trisubstituted Benzo[1,4]-Diazepin-5-one Derivatives

Solid-phase synthesis of 3,4-dihydro-benzo­[e]­[1,4]­diazepin-5-ones with three diversity positions is described. Various primary amines were used as the starting material and immobilized on the polystyrene resin equipped with different acid-labile linkers. Polymer-supported amines were converted to α-aminoketones with the use of their sulfonylation with the 4-nitrobenzensulfonylchoride (4-Nos-Cl) and subsequent alkylation with α-bromoketones. After the cleavage of the 4-Nos group, the corresponding α-aminoketones were acylated with various <i>o</i>-nitrobenzoic acids. Reduction of the nitro group followed by spontaneous on-resin ring closure gave the target immobilized benzodiazepines. After acid-mediated cleavage the products were obtained in very good crude purity and satisfactory yields, which makes the developed method applicable for simple library synthesis of the corresponding derivatives in a combinatorial fashion