Trilobite assemblage of Calceola-bearing beds in Acanthopyge Limestone (Choteč formation, middle Devonian, Eifelian, Prague Basin, the Czech republic)

The trilobite assemblage of Calceola-bearing beds in the upper part of Acanthopyge Limestone (Choteč Formation, Eifelian) in the Koněprusy area, the Czech Republic, is described. Together with occurrence of Calceola, it indicates absence of significant palaeogeographic barriers restricting the distribution of the Rhenish-Type faunas in the Middle Devonian. The generic composition of the gathered trilobite assemblage somewhat differs from typical Acanthopyge-Phaetonellus assemblage characteristic for the Acanthopyge Limestone facies in possible absence and/or very rare occurrence of Phaetonellus, and only infrequent occurrence of Acanthopyge. Phacopid Chotecops cf. hoseri (Hawle et Corda, 1847) distinctly dominates; all other taxa are rather rare. Important is an occurrence of scutelluids of the Scutellum sensu lato group (preservation of remains does not enable more precise determination) and Longiproetus(?). Trilobite remnants are generally poorly preserved and very fragmented (only minute shields are not affected), which support a high-dynamic, shallow-water original environment

Živočichové v aerofytickém mechu

Aerofytický mech je snadno dostupným materiálem pro praktická cvičení téměř kdekoliv a v kteroukoliv roční robu. Lze v něm demonstrovat několik skupin mikroskopických živočichů pomocí běžné mikroskopické techniky.Tento material vznikl z finanční podpory Evropského sociálního fondu a státního rozpočtu České republiky v rámci projektu „Popularizace vědy a badatelsky orientované výuky“, registrační číslo CZ.1.07/2.3.00/45.0007

Hálky jako příklad ekologických vztahů mezi živočichem a rostlinou

Hálky jsou výborným badatelským objektem pro ekologicky zaměřenou exkurzi i laboratorní praktikum. Jsou klasickým případem interakce dvou zcela rozdílných organismů.Hálky se často vyskytují na oslabených stromech na chudé půdě, při okrajích parků a ekotonech, např. okrajích pasek. Jsou snadno dostupným biologickým objektem. Při exkurzi pozorně prohlížíme spodní stranu listů. Nejlepšími stromy s nápadnými hálkami jsou na našem území duby. Pěkné hálky nalezneme i na lipách, javorech a bucích. Na keřích jsou nejčastěji hálky přítomny na růži šípkové. Přítomnost nebo nepřítomnost hálek záleží na mnoha faktorech. Proto v některých letech na stejném místě nalezneme četné hálky, i více jejich druhů, zatímco z jiných letech na hálky téměř nenarazíme. Přítomnost hálek souvisí i s dvouletými cykly některých skupin žlabatek.Tento material vznikl z finanční podpory Evropského sociálního fondu a státního rozpočtu České republiky v rámci projektu „Popularizace vědy a badatelsky orientované výuky“, registrační číslo CZ.1.07/2.3.00/45.0007

Který druh reprezentuje typického hlavonožce?

V práci jsou prezentovány výsledky výzkumu zaměřeného na prezentaci druhů hlavonožců v česky psaných učebnicích a dětských encyklopediích. Výzkum ukazuje, že nejčastěji zmiňovanými druhy jsou sépie obecná (Sepia officinalis) a chobotnice pobřežní (Octopus vulgaris). Dalším častěji citovaným druhem jsou loděnka hlubinná (Nautilus pompilius). Další druhy jsou zmiňovány řídce, avšak některé knihy vyobrazují unikátní a často pozoruhodné hlubokomořské druhy. Patrný je posun od detailních informací o druhu, jeho významu a využití ve starších učebnicích k prezentování druhu jako obecného modelového reprezentanta hlavonožců s určitou unikátní morfologií a anatomií v moderních knihách.The article presents the result of research aimed to presentation of cephalopods in text-books and children’s encyclopedias written in Czech language. The result indicates, that Common cuttlefish (Sepia officinalis) and Common octopus (Octopus vulgaris) are the most frequent examples of cephalopods in text-books despite the date of print. Chambered nautilus (Nautilus pompilius) is the third commonly displayed species. Other cephalopds are rarely presented, but some books illustrated unique and peculiar deep-ocean species. The shift from detailed information about the species, including its economical significance and practical usage presented in older text-books to species presented as a general model of cephalopod animal with particular anatomy and morphology in modern text-books is obvious

Struggle for phosphorus and the Devonian overturn

Organisms with external phosphatic shells diversified and became abundant at the beginning of the Early Paleozoic but gradually declined and were rare by its end. The decreasing availability of phosphorus in oceans is thought to be responsible for this evolutionary trend. Responses of organisms to changes in the phosphorus cycle can be traced to the late Neoproterozoic, and likely had a significant role in the Cambrian explosion, the Great Ordovician Biodiversification Event (GOBE), and the Devonian nekton revolution. Effective use of phosphorus by vertebrates during the Devonian nekton revolution caused the phosphorus pool to shift from benthic external shells to the skeletons of pelagic vertebrates, and moved the marine faunas toward the dominance patterns and ecological structure of the Modern Evolutionary Fauna

Trilobite biostratigraphy of the Králův Dvůr Formation (upper Katian, Prague Basin, Czech Republic): global faunal changes or facies-related distribution?

Eight trilobite associations and sub-associations have been distinguished in the late Katian Králův Dvůr Formation. Spatial distribution of these associations reflects lithology but their succession was dictated also by global climatic changes and palaeogeographical positioning. Locally developed “Podolí Ore Horizon” trilobite association contains low-diversity but specific forms showing survivals from the underlying Bohdalec Formation combined with the late Katian taxa (Chlustinia, Duftonia, Onnia, etc.). The Amphitryon – Kloucekia Association is newly established for the lower two thirds of the formation. It is characterized by abundant benthic scavenger-predators accompanied by filter feeders and common pelagic/nektic predators. Within Amphitryon –Kloucekia Association can be distinguished four sub-Association 1) the newly established Onnia ultima sub-Association is characterized by a dominance of Onnia and Flexicalymene; it is developed at the lowermost levels of the formation, 2) the deeper-water Nankinolithus granulatus sub-Association (originally established as horizon), 3) rather shallow-water, brachiopod-dominated Dedzetina-Tretaspis sub-Association with rare trilobites and 4) the trilobite-dominated Tretaspis anderssonni sub-Association (originally horizon). Last three sub-associations are considered as rather facies-related, with limited stratigraphical applicability only. Impure bioclastic limestone below top of the formation contains a rich shallow- and temperate-water Marekolithus kosoviensis Association, which better corresponds with the original horizon concept. This association is dominated by small benthic scavenger-predator trilobites, which are associated by the filter feeder Marekolithus. The Mucronaspis Association of medium-sized scavenger-predators is characteristic for the uppermost portion of formation and persisted till the early onset of the glaciation at the base of Hirnantian. Minute detritus feeders are rare but present in all the above-discussed associations excluding the last one

Electrical Contact Resistance of Large-Area Graphene on Pre-Patterned Cu and Au Electrodes

Contact resistance between electrically connected parts of electronic elements can negatively affect their resulting properties and parameters. The contact resistance is influenced by the physicochemical properties of the connected elements and, in most cases, the lowest possible value is required. The issue of contact resistance is also addressed in connection with the increasingly frequently used carbon allotropes. This work aimed to determine the factors that influence contact resistance between graphene prepared by chemical vapour deposition and pre-patterned Cu and Au electrodes onto which graphene is subsequently transferred. It was found that electrode surface treatment methods affect the resistance between Cu and graphene, where contact resistance varied greatly, with an average of 1.25 ± 1.54 kΩ, whereas for the Au electrodes, the deposition techniques did not influence the resulting contact resistance, which decreased by almost two orders of magnitude compared with the Cu electrodes, to 0.03 ± 0.01 kΩ

Cambrian and Ordovician Fossil-Lagerstätten in the Barrandian area

Exceptionally preserved fossils showing typical characters of the so called Konservat-Lagerstätten are shortly mentioned from Cambrian and Ordovician sediments of the Barrandian area. Fossils with well preserved soft parts were ascertained in several different levels of two Cambrian units of the Příbram-Jince Basin as well as in diverse levels of the Skryje-Týřovice Basin. Other exceptionally preserved fossils are shortly discussed from numerous Lower to Upper Ordovician levels of the Prague Basin

Electrical Contact Resistance of Large-Area Graphene on Pre-Patterned Cu and Au Electrodes

Contact resistance between electrically connected parts of electronic elements can negatively affect their resulting properties and parameters. The contact resistance is influenced by the physicochemical properties of the connected elements and, in most cases, the lowest possible value is required. The issue of contact resistance is also addressed in connection with the increasingly frequently used carbon allotropes. This work aimed to determine the factors that influence contact resistance between graphene prepared by chemical vapour deposition and pre-patterned Cu and Au electrodes onto which graphene is subsequently transferred. It was found that electrode surface treatment methods affect the resistance between Cu and graphene, where contact resistance varied greatly, with an average of 1.25 ± 1.54 kΩ, whereas for the Au electrodes, the deposition techniques did not influence the resulting contact resistance, which decreased by almost two orders of magnitude compared with the Cu electrodes, to 0.03 ± 0.01 kΩ.Contact resistance between electrically connected parts of electronic elements can negatively affect their resulting properties and parameters. The contact resistance is influenced by the physicochemical properties of the connected elements and, in most cases, the lowest possible value is required. The issue of contact resistance is also addressed in connection with the increasingly frequently used carbon allotropes. This work aimed to determine the factors that influence contact resistance between graphene prepared by chemical vapour deposition and pre-patterned Cu and Au electrodes onto which graphene is subsequently transferred. It was found that electrode surface treatment methods affect the resistance between Cu and graphene, where contact resistance varied greatly, with an average of 1.25 ± 1.54 kΩ, whereas for the Au electrodes, the deposition techniques did not influence the resulting contact resistance, which decreased by almost two orders of magnitude compared with the Cu electrodes, to 0.03 ± 0.01 kΩ

Dendritic microborings in brachiopod shells from the Silurian of the Barrandian area, Czech Republic

Four types of dendritic microborings preserved as natural casts were observed on the surfaces of brachiopod shells from the Silurian in Central Bohemia: Rhopalondendrina jakubinka isp. nov., ? Clionolithes isp., and an indeterminate dendrinid are of Llandovery (Aeronian) age, Clionolithes amoebae isp. nov. is of Ludlow (Gorstian) age. Rhopalondendrina jakubinka forms a dense plexus of thin rhizoidal tunnels extending from a broad and curved entrance tunnel. ? Clionolithes isp. forms characteristically rarely branching thin meandering tunnels with a globular central node, while C. amoebae forms rosette-like microborings with sinuously curved primary branches and scarce lateral branches of smaller size. Microborings are present both on outer and inner surfaces of shells; their location and number confirm massive infestation of dead shells which were exposed on the sea floor for long time intervals and which were not affected by mechanical abrasion of the shells. This indicates narrow ecological limits for these endobionts, most likely within the deeper euphotic zone