32 research outputs found
CURRENT MEASURES AGAINST OPHTHALMIC COMPLICATIONS OF DIABETES MELLITUS-A SHORT REVIEW
Diabetes mellitus (DM) is a metabolic disorder, whose prevalence is predicted to rise shortly. The present review focuses on the various ocular complications associated with DM, and the various ophthalmic formulation approaches developed to treat the same. Diabetic macular edema (DME), diabetic retinopathy, cataracts, and glaucoma are some of the major vision-threatening complications linked to DM. The ocular route of drug delivery has undergone several advancements in recent decades, the introduction of various novel drug delivery systems (DDS), various modifications in the existing formulation approaches, development of custom-designed personalized medications, being some of the major developments introduced in the field of ocular drug delivery. Due to the application of state-of-the-art technologies in the field of innovations related to ocular DDS, patients have been immensely benefited by the current modes of ocular treatment imparting fewer side effects, enhanced penetration, sustained drug effect, and so on. The present review includes and emphasizes the gradual development that has occurred from the conventional ophthalmic dosage forms to the currently reported novel ocular drug delivery approaches along with the related clinical research works
A marine to fluvial transition in the Paleoproterozoic Koolbye Formation, Turee Creek Group, Western Australia
Although no unambiguous biogenic criteria exist to discriminate Precambrian shallow-marine succes-sions from fluvial deposits, physical sedimentological evidence, including an association of primarysedimentary structures and textures, stratigraphic position, and comparison with Phanerozoic and Mod-ern examples has been found useful in identifying these deposit types. Our high resolution sedimentaryfacies analysis coupled with new mapping clearly indicates shallow-marine to beach-aeolian to fluvialsedimentation in the Paleoproterozoic Koolbye Formation of the Turee Creek Group, Western Australia.A falling stage systems tract within the Koolbye Formation has been documented. Our sedimentary faciesanalysis in combination with sedimentological analysis of the underlying Kungarra Formation indicatesdevelopment of at least three falling stage systems tracts within the Turee Creek Group across the rise ofatmospheric oxygen (the Great oxidation event).University of New South Wales (UNSW) and the Agouron Institute.http://www.elsevier.com/locate/precamres2016-03-31hb201
A squall by the seashore ca 2.3 billion years ago : raindrop imprints in a Paleoproterozoic tidal flat deposit, Kungarra Formation, Western Australia
In this contribution, we describe the occurrence of well-preserved Paleoproterozoic raindrop impact imprints on two surfaces of rippled siltstoneāmudstone from the uppermost part of the Paleoproterozoic Kungarra Formation, Turee Creek Group, Western Australia. The raindrop imprints appear on the tops of two immediately overlying bedding surfaces in siltstone, near the top of a shallowing upward sequence that progresses from sandstone to mudstone. Imprints are circular to elliptical with an average diameter of 2ā3 mm and a maximum length of 6.3 mm when elliptical. Flat ripple crest morphologies, varied ripple crest orientations, and marks of standing water in the ripple troughs indicate very shallow water conditions. When combined with sedimentological data from the underlying Kungarra Formation (shallow marine sandstones and siltstones), and mature quartz arenites of the overlying Koolbye Formation (mixed tidal, beach, fluvial and eolian), the interval examined is interpreted as a tidal flat deposited during a falling stage systems tract.University of New South Wales, Agouron Institute and University of New South
Wales.http://www.tandfonline.com/loi/taje202016-09-30hb201
Late Neoarchaean-Palaeoproterozoic supracrustal basin-fills of the Kaapvaal craton : relevance of the supercontinent cycle, the "Great Oxidation Event" and "Snowball Earth"?
The application of the onset of supercontinentality, the āGreat Oxidation Eventā (GOE) and the first global
scale glaciation in the Neoarchaean-Palaeoproterozoic as panacea-like events providing a framework or
even chronological piercing points in Earthās history at this time, is questioned. There is no solid evidence
that the Kaapvaal craton was part of a larger amalgamation at this time, and its glacigenic record is
dominated by deposits supporting the operation of an active hydrological cycle in parallel with glaciation,
thereby arguing against the āSnowball Earth Hypothesisā. While the Palaeoproterozoic geological
record of Kaapvaal does broadly support the GOE, this postulate itself is being questioned on the basis of
isotopic data used as oxygen-proxies, and sedimentological data from extant river systems on the craton
argue for a prolongation of the greenhouse palaeo-atmosphere (possibly in parallel with a relative
elevation of oxygen levels) which presumably preceded the GOE. The possibility that these widespread
events may have been diachronous at the global scale is debated.The National Research Foundation and University of Pretoria, South
Africa.http://www.elsevier.com/locate/marpetgeonf201
A case study of microbial mat-related features in coastal epeiric sandstones from the Paleoproterozoic Pretoria group (Transvaal supergroup, Kaapvaal craton, South Africa) : the effect of preservation (reflecting sequence stratigraphic models) on the relationship between mat features and inferred paleoenvironment
The Magaliesberg Formation sandstones within the upper part of the Pretoria Group are interpreted as a
second-order highstand systems tract within an overall clastic epeiric marine setting, where episodic
braided fluvial systems fed sediment directly into a tidally dominated coastline setting. Mat-related features
are abundantly preserved within the inferred tidal flat and supratidal deposits. The Daspoort Formation
sandstones at a lower stratigraphic level are ascribed to a closely analogous palaeoenvironmental setting,
yet have hardly any preserved mat features at all; they are ascribed to a second-order transgressive systems
tract in a sequence stratigraphic framework. During highstand the depositional systems are inferred to have
aggraded, thus preserving the mat-related features formed in Magaliesberg intertidal-supratidal
environments. During second-order transgression, the formation of the wave/tidal ravinement surface in the subtidal/intertidal environments largely obliterated the features of the Daspoort intertidal and supratidal
environments, leading to a paucity of mat-related structures in the preserved Daspoort succession. This case
study thus supports the application of mat-related features to integrated palaeoenvironmental and sequence
stratigraphic analysis, while emphasizing the role of preservation.The National Research Foundation, South Africa, and the University of Pretoria.http://www.elsevier.com/locate/sedgeonf201
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Sedimentology, chemostratigraphy, and stromatolites of lower Paleoproterozoic carbonates, Turee Creek Group, Western Australia
The ca. 2.45ā2.22 Ga Turee Creek Group, Western Australia, contains carbonate- rich horizons that postdate earliest Proterozoic iron formations, bracket both Paleoproterozoic glaciogenic beds and the onset of the Great Oxidation Event (GOE), and predate ca. 2.2ā2.05 Ga Lomagundi-Jatuli C-isotopic excursion(s). As such, Turee Creek carbonate strata provide an opportunity to characterize early Paleoproterozoic carbonate sedimentation and carbon cycle dynamics in the context of significant global change. Here, we report on the stratigraphy, sedimentology, petrology, carbon isotope chemostratigraphy, and stromatolite development for carbonate-rich successions within the pre-glacial part of the Kungarra Formation and the postglacial Kazput Formation. Kungarra carbonate units largely occur as laterally discontinuous beds within a thick, predominantly siliciclastic shelf deposit. While this succession contains thin microbialite horizons, most carbonates consist of patchy calcite overgrowths within a siliciclastic matrix. C-isotopic values show marked variation along a single horizon and even within hand samples, reflecting spatially and temporally variable mixing between dissolved inorganic carbon in seawater and isotopically light inorganic carbon generated via syn- and post-depositional remineralization of organic matter. In contrast, the Kazput carbonates consist of subtidal stromatolites, grainstones, and micrites deposited on a mixed carbonate-siliciclastic shelf. These carbonates exhibit moderate Ī“13 C values of -2ā° to +1.5ā° and likely preserve a C-isotopic signature of seawater. Kazput carbonates, thus, provide some of the best available evidence that an interval of unexceptional C-isotopic values separates the Lomagundi-Jatuli C-isotopic excursion(s) from the initiation of the GOE as inferred from multiple sulfur isotopes (loss 4 of mass independent fractionation). The Kazput Formation also contains unusual, m-scale stromatolitic buildups, which are composed of sub-mm laminae and discontinuous, convex upward lenticular precipitates up to a few mm in maximum thickness. Laminae, interpreted as microbial mat layers, contain quartz and clay minerals as well as calcite, whereas precipitate lenses consist of interlocking calcite anhedra, sometimes showing faint mm-scale banding. These cements formed either as infillings of primary voids formed by gas emission within penecontemporaneously lithified mats, or as local seafloor precipitates that formed on, or within, surface mats. It is possible that both mechanisms interacted to form the unique Kazput stromatolites. These microbialites speak to a distinctive interaction between life and environment early in the Paleoproterozoic Era.Earth and Planetary Science
Palaeoproterozoic of India
The Indian shield represents a vast repository of the Palaeoproterozoic geological record. Built over the four large amalgamated Archaean nuclei (Dharwar, Bastar, Singhbhum and AravalliāBundelkhand) the major and minor Palaeoproterozoic sedimentary basins and supracrustal sequences in India are comparable in scale, and perhaps also in development, to those of North America, Africa, Australia and Brazil. The deformation of these supracrustal sequences, attendant metamorphism and emplacement of plutonic bodies hold important clues to their connection with major orogenies. Research in these areas has led to investigations into global correlation, which in turn has had a direct bearing on refining models of Palaeoproterozoic supercontinent assembly and break-up. This book covers various aspects of regional geology as well as broader issues of the Indian Palaeoproterozoic geology and its global context. It is an outcome of the UNESCO-IGCP 509 Palaeoproterozoic Supercontinents and Global Evolution research project. Ā© 2012 The Geological Society of London
Petrography and geochemistry of Mesoarchaean komatiites from the eastern Iron Ore belt, Singhbhum craton, India, and its similarity with āBarberton type komatiiteā
The Mesoarchaean supracrustals of the GorumahishaniāBadampahar belt, eastern India record sedimentationāvolcanism like most other contemporary greenstone belts over the world. The current study reports unambiguous komatiitic rocks from Tua-Dungri hill, GorumahishaniāBadampahar belt, Jharkhand and presents a petrological and geochemical inventory of these very interesting rocks. The Tua-Dungri komatiites are characterised by a well distinguishable cumulate, platy and random spinifex zone. These Tua-Dungri komatiites are rich in SiO2 (47ā50 wt%) like Barberton type komatiite or modern day boninite. Their Al depleted nature (Al2O3 = 1.36ā2.95 wt%) with very low Al2O3/TiO2 (3.4ā6.5) and high CaO/Al2O3 (2ā3), high LREE/HREE ratios show further resemblance with the Barberton komatiite. The Tua Dungri komatiite data along with published geochemical, sedimentological and stratigraphic data from the Iron Ore Group of rocks suggest mantle plume activity during the Mesoarchaean on the Singhbhum craton
Experimental study of the system grossularite-spessartine at P<SUB>H<SUBSUB>2</SUBSUB>0</SUB>= P<SUB>Total</SUB> 1 kbar and variable temperatures
The system grossulatite-spessartine hasbeen studied at 1 kbar and 700, 750 and 80Ā°C. Based onX-ray diffraction study and refractive indexmeasurement it was observed that there is continuoussolid solution relationship between the two endmembers; there is thus no basis for including grossulariteand spessartine into two separate groups on the basis ofthe assumption that there may be immiscible relation between these two garnets