Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 8

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  sponges
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
Stromatoporoids of the family Actinostromatidae are common constituents of Givetian to Frasnian (Devonian) organic buildups. The species-level structure of actinostromatid assemblages from the Devonian of southern Poland is described in the present paper, with special emphasis on ecological factors that influenced species composition of the communities. Nine species of the genera Actinostroma and Bifariostroma are distinguished. Members of the family Actinostromatidae predominated in stromatoporoid assemblages within lower Frasnian carbonate buildup margins. The most diverse actinostromatid faunas were found within the middle Givetian Stringocephalus Bank, in the upper Givetian–lower Frasnian biostromal complex and in the lower Frasnian organic buildups. Species-level biodiversity was lowest within detrital facies which surrounded the Frasnian carbonate buildups. Species of Actinostroma with well-developed colliculi are commonest within the middle Givetian to early Frasnian coral-stromatoporoid biostromal complexes, whereas species with strongly reduced colliculi predominate early-middle Frasnian organic buildups. The skeletal structure of actinostromatids reflects environmental changes, documenting a transition from species with thin, close-set pillars and widely spaced laminae (common in the middle Givetian) to those with long, thick pillars and megapillars (in Bifariostroma), which were predominant during the early and middle Frasnian. The distribution of growth forms among species reveals a significant intraspecific variation. Species of Actinostroma can be either tabular or low domical, depending on the palaeoenvironmental setting. Thus, the present study confirms that stromatoporoid morphology was influenced by environmental conditions.
EN
Eight species of ventriculitid sponges (Order Lychniscosida Schrammen, 1903) are described from the Upper Turonian marly limestones and Lower Coniacian marls of the Opole Trough (southern Poland). Among them four have not previously been noted in this area. Two species, Astropegma stellata (Roemer, 1840) and Leiostracosia robusta (Schrammen, 1902) are reported from Turonian strata for the first time. The occurrence of ventriculitid sponges in the Upper Turonian–Lower Coniacian succession of the Opole Trough indicates a soft- bottom, calm-water environment, with depths below the storm-wave base and a low rate of sedimentation.
EN
The sponge fauna from the Upper Campanian.lowermost Maastrichtian succession of the Middle Vistula River valley (central Poland) is represented mainly by dictyid hexactinellid sponges (Hexactinosida and Lychniscosida). Their greatest abundance and taxonomic variability is noted in the "Inoceramus" inkermanensis Zone (Upper Campanian), and they are less diverse in the overlying (Upper Campanian) Trochoceramus costaecus Zone and lower "Inoceramus" redbirdensis Zone. In the upper "Inoceramus" redbirdensis Zone (basal Maastrichtian in the sense of the Tercis rather than the Boreal definition) they are extremely rare. With the beginning of the Maastrichtian the number of dictyid sponges gradually increases. The observed changes in the abundance and taxonomic variability of the dictyid sponges indicate environmental changes in the latest Campanian.earliest Maastrichtian sea in the area. It seems that changes in basin bathymetry, confined to eustatic sea-level changes in the latest Campanian and early Maastrichtian, were the most important factor. Progressive shallowing of the basin in the latest Campanian drastically restricted the development of dictyids. In the peak regression, the sea level could have fallen to only several tens of metres. The gradual recovery of the sponge assemblages correlates with subsequent deepening of the basin with the start of the Maastrichtian.
EN
Hexactinellid sponges are extremely abundant in the basal sequence of the Santonian of the Kraków region. This is the only known area in Poland where Santonian deposits with sponges are exposed. The studied sponges are redeposited and probably represent a Santonian or/and Coniacian assemblage. They inhabited a quiet, deeper part of the epicontinental sea that covered the southern part of Poland in Late Cretaceous times. This paper is a taxonomic revision of sponges collected from this region by the late Prof. J. Małecki. Based on existing old collections and newly collected material comprising 1020 specimens, 34 species have been described, including 14 belonging to the Hexactinosida and 20 to the Lychniscosida. All sponge species occurring in the Santonian succession of the Kraków area are also known from various Late Cretaceous sponge assemblages of Europe. Five species described, i.e. Eurete halli (Schrammen), Lefroyella favoidea Schrammen, Spirolophia tortuosa (Roemer), Coeloptychium lobatum Goldfuss, and Wollemannia araneosa Schrammen have not been so far noted in pre-Campanian deposits. The examined assemblage is particularly similar to the sponge fauna from the Middle Coniacian - Middle Santonian deposits of England and from the Lower Santonian of Russia (Saratov area).
EN
Phosphatized sponges from the Santonian of the Wielkanoc Quarry are represented by 11 species of Hexactinosida and 16 species of Lychniscosida. Their species composition is most similar to the Micraster coranguinum Zone fauna (Middle Coniacian - Middle Santonian) of England. Three preservational groups of sponges are distinguished: 'white', 'beige' and 'dark'. They are infilled by phosphatized foraminiferal/foraminiferal-calcisphere wackestone and are contained in the marly calcareous inoceramid packstone. The sponges indicate a calm and relatively deep (> 100 m) life environment. After burial, phosphatization and exhumation, the fossil sponges were redeposited in Upper Santonian strata. The 'white' and 'beige' groups were transported laterally over a very short distance or represent lag deposits. The rolled and crushed sponges of the 'dark' group were exhumed and phosphatized more than once. They could be redeposited (reworked) nearly in the same place and/or transported from some longer distances (but not from outside the Cracow Swell). The phosphatized sponges document the former presence in the area of part of theMiddle Coniacian through Middle Santonian succession, which was removed secondarily by subsequent erosion.
EN
The sponge fauna from the Danian glauconitic sandstone as exposed at Nasiłów, contains all species known from the underlying Upper Maastrichtian siliceous chalk and, additionally, some species not documented hitherto from the latter unit. The stratigraphic ranges of the all studied sponges indicate their Late Maastrichtian age; there are no Danian sponges in the glauconitic sandstone. Two assemblages of sponges may be distinguished in the glauconitic sandstone, based on the analysis of the infilling of their interspicular space: 1) sponges infilled with phosphatized siliceous chalk and 2) sponges infilled with phosphatized glauconitic siliceous chalk. Petrographic study indicates that the host deposit of the first assemblage was a siliceous chalk. The second type originated from a glauconitic siliceous chalk unit, probably equivalent to the so-called Żyrzyn Beds of Late Maastrichtian age. The glauconitic chalk orginally overlain the siliceous chalk at Nasiłów, but has been subsequently eroded. Detailed analysis of the relations between two types of infillings allows to distinguish a latest Maastrichtian stage of erosion after deposition of the siliceous chalk, not recognised by previous authors. In this erosional stage, phosphatized sponges originally embedded in siliceous chalk were re-exposed and subsequently buried during the deposition of the glauconitic siliceous chalk unit.
EN
Siliceous sponges are extremely abundant in the Upper Campanian-Maastrichtian opokas and marls of the Middle Vistula River Valley, situated in the western edge of the Lublin Basin, part of the Cretaceous German-Polish Basin. This is also the only one area in Poland where strata bearing the Late Maastrichtian sponges are exposed. The presented paper is a taxonomic revision of sponges collected from this region. Based both on existing and newly collected material comprising ca. 1750 specimens, 51 species have been described, including 18 belonging to the Hexactinosida, 15 - to the Lychniscosida and 18 - to Demospongiae. Among them, 28 have not been so far described from Poland. One new genus Varioporospongia, assigned to the family Ventriculitidae Smith and two new species Varioporospongia dariae sp. n. and Aphrocallistes calciformis sp. n. have been described. Comparison of sponge fauna from the area of Podilia, Crimea, Chernihov, and Donbas regions, as well as literature data point to the occurrence of species common in the analysed area and to the basins of Eastern and Western Europe. This in turn indicates good connections between particular basins of the European epicontinental sea during the Campanian-Maastrichtian. Analysis of the taxonomic composition of the Middle Vistula assem- blage suggests that the occurring sponge fauna is transitional between the faunas of Eastern and Western Europe, what may be linked with the central location of the Lublin Basin in the European epicontinental sea. The gradual upward decrease of taxonomic diversity of the Hexactinosida and Lychniscosida in the studied succession points to gradual basin shallowing, what is consistent with the global regressive trend by the end of the Cretaceous. The domination of the Hexactinellida over the lithistids in terms of diversity and abundance in the entire section allows us to estimate the maximum depth of the Late Campanian basin as 200-250 m and to constrain the minimum depth during the latest Maastrichtian as about 100 m.
8
Content available remote Application of Selected Usability Forms of Chitosan for Dressings
EN
Requirements for biological dressings have been increasing in recent years. In addition to their fundamental protective function, biological dressings shorten of the wound healing process or even can replace patients' lost skin of. This paper presents an investigation into the application of several usable forms of chitosan such as films, sponges, and hydrogels for wound dressing manufacture. The unique properties of microcrystalline chitosan such as biodegradibility, ability to form film, non-toxicity and biocompatibility, as well as its high miscibility with other polymers and its bioactivity, make this polymer an unusually attractive reproducible natural material for wound healing dressings.
PL
W ostatnich latach można zauważyć wzrastające zapotrzebowanie na biologiczne środki opatrunkowe. Opatrunki biologiczne, poza swoją podstawową funkcją zabezpieczającą, przyczyniają się do skrócenia procesu gojenia ran oraz mogą zastępować skórę pacjentów. W artykule przedstawiono ocenę zastosowania różnych form mikro-krystalicznego chitozanu, takich jak błony, gąbki i hydrożele, do produkcji środków opatrunkowych. Unikalne właściwości mikrokrystalicznego chitozanu, takie jak biodegradowalność, zdolność do tworzenia błon, brak toksyczności, bioaktywność, biokompatybilność, jak również zdolność do mieszania z innymi polimerami, czynią ten polimer niezmiernie atrakcyjnym, reproduktywnym materiałem naturalnym do produkcji opatrunków.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.