Production of tool for pressing formed shim into flange

Bakalářská práce řeší návrh nástroje pro zalisování tvarové podložky do příruby vysokotlakého čerpadla. Teoretická část závěrečného projektu shrnuje poznatky z teorie a technologie tváření kovů a slitin za studena. V praktické části závěrečné práce jsou zpracovány tři varianty upevnění tvarové podložky do příruby vysokotlakého čerpadla. Na základě provedených zkoušek byla pro opravy přírub čerpadel vybrána varianta řešení II, která se jeví jako nejvýhodnější. Příruba vysokotlakého čerpadla je zhotovena z hliníkové slitiny AlSi1MgMn. Tvarová podložka je zhotovena stříháním z ocelového plechu C75 dle DIN 17222 (ČSN 12 081). Výkres nástroje byl zpracován na základě nejvhodnější technologické varianty oprav. Lisovací nástroj je vyroben z oceli 19 452 a zakalen na HRC 60-4. Předpokládaná výrobní sérii je 7000ks za rok. Oprava přírub čerpadel se uskutečňuje na jednoúčelovém stroji.The Baccalaureate Thesis deals with the design of a tool for fixing of thrust rings in flanges of high pressure fuel injection pumps. The theoretical part of the final project summarizes both theory-based and cold metal and alloy working-based knowledge. Three options of fixing the thrust ring in the flange of a high pressure fuel injection pump have been developed. Based on tests carried out, the option II has been chosen for repairs of fuel injection pumps flanges since it seems to be the most advantageous one. The high pressure fuel injection pump flange is made of AlSilMgMn aluminium alloy. The thrust ring is made by C 75 sheet steel stamping according to DIN 17222 (ČSN 12081). The tool drawing was made on the basis of the best-fit technology repair option. Stamping tools are made of 19 452 steel and hardened to HRC 60-4. The assumed yearly output amounts to 7000 pieces. A special purpose machine is used for repairing fuel injection pump flanges.

Silver covalently bound to cyanographene overcomes bacterial resistance to silver nanoparticles and antibiotics

The ability of bacteria to develop resistance to antibiotics is threatening one of the pillars of modern medicine. It was recently understood that bacteria can develop resistance even to silver nanoparticles by starting to produce flagellin, a protein which induces their aggregation and deactivation. This study shows that silver covalently bound to cyanographene (GCN/Ag) kills silver-nanoparticle-resistant bacteria at concentrations 30 times lower than silver nanoparticles, a challenge which has been so far unmet. Tested also against multidrug resistant strains, the antibacterial activity of GCN/Ag is systematically found as potent as that of free ionic silver or 10 nm colloidal silver nanoparticles. Owing to the strong and multiple dative bonds between the nitrile groups of cyanographene and silver, as theory and experiments confirm, there is marginal silver ion leaching, even after six months of storage, and thus very high cytocompatibility to human cells. Molecular dynamics simulations suggest strong interaction of GCN/Ag with the bacterial membrane, and as corroborated by experiments, the antibacterial activity does not rely on the release of silver nanoparticles or ions. Endowed with these properties, GCN/Ag shows that rigid supports selectively and densely functionalized with potent silver-binding ligands, such as cyanographene, may open new avenues against microbial resistance.Web of Scienceart. no. 200309

Dynamic changes in genomic and social structures in third millennium BCE central Europe

Europe’s prehistory oversaw dynamic and complex interactions of diverse societies, hitherto unexplored at detailed regional scales. Studying 271 human genomes dated ~4900 to 1600 BCE from the European heartland, Bohemia, we reveal unprecedented genetic changes and social processes. Major migrations preceded the arrival of “steppe” ancestry, and at ~2800 BCE, three genetically and culturally differentiated groups coexisted. Corded Ware appeared by 2900 BCE, were initially genetically diverse, did not derive all steppe ancestry from known Yamnaya, and assimilated females of diverse backgrounds. Both Corded Ware and Bell Beaker groups underwent dynamic changes, involving sharp reductions and complete replacements of Y-chromosomal diversity at ~2600 and ~2400 BCE, respectively, the latter accompanied by increased Neolithic-like ancestry. The Bronze Age saw new social organization emerge amid a ≥40% population turnover.Peer reviewe