395 research outputs found

    Fabrication of Perovskite-type Oxide BaPbO3 Nanoparticles and their Efficiency in Photodegradation of Methylene Blue

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    BaPbO3 perovskite was prepared by the sol-gel method. The physical and chemical properties of catalyst were characterized by XRD, TEM, SEM, EDX and IR techniques. The photocatalytic activity of the sample was evaluated by photocatalytic decomposition of methylene blue (MB) dye under UV irradiation. The results of XRD indicate that the perovskite-type oxide (BaPbO3) is crystal at 700 °C. The XRD, TEM and SEM revealed that BaPbO3 particles are prepared in the nano-size regime. The results show that the degradation efficiency of methylene blue (MB) by BaPbO3 is higher than rutile under similar conditions.Keywords: Perovskite-type oxide, nanopowder, dye removal, methylene blue

    Distribution of zooplankton in the southern Caspian Sea

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    The zooplanktons were studied in spring, autumn and winter in the southern Caspian Sea in 1996. Sampling carried out in four season. In each season, 180 specimens were identified and their frequency calculated per m^3. 55 species of zooplanktons were identified including 55% Cladocera, 15% Copepoda and 11 % Rotatoria, 9% other groups such as meroplanktons. The maximum species diversity was observed for Cladocera and the maximum frequency were observed for Copepoda. The Copepoda affected on abundance of zooplanktons as this frequency included in spring, summer, autumn and winter that were 38% to 97%, 22% to 92%, 71 % to 99% and 31 % to 92%, respectively. In summer, the Copepoda and lamellibranchiata larvae had main role in formation of zooplankton population in western region of the southern Caspian Sea, but in autumn, 70% of zooplankton population were copepods. The frequency of zooplanktons in spring, summer, autumn and winter were calculated 4081 to 20143; 7812 to 65741; 10850 to 34406 and 4510 to 20576 inch/m^3, respectively. The maximum biomass was observed during summer with 200 mg/m^3

    Fabrication and Antibacterial Performance of Nano-silver-Doped Monoliths by the Sol-Gel Method

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    The organic-inorganic hybrids of glycine, tetraethylortho silicate (TEOS) and triethylphosphate (TEP) doped with silver ions were prepared by the sol-gel method. After moulding and heating at 600 °C to remove organic compound, porous Ag/P2O5-SiO2 monoliths were obtained. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectrum, transmission electron microscopy (TEM), infrared spectroscopy (FT-IR) and scanning tunnelling microscopy (STM) were used to structurally study monoliths. Surface area, pore volume and swelling degree of the samples were adjusted with different contents of TEP in the starting composition. Ag ions were stably released into the water at 30 °C for 28 days. Antibacterial experimentation revealed that such materials, treated at 600 °C, could restrain Escherichia coli effectively.KEYWORDS Antibacterial effect, nano-silver, phosphorous, organic–inorganic hybrid, sol-gel.

    Hydrology and hydrobiology of Chaloos River

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    The Chaloos River originates from Alborz Mountain and enters into the Caspian Sea in Chaloos city. Five stations were chosen in different areas for the study during 1371 to 1372 (1992-93). Total variation range of hardness decreased 1 to 5 station, but measure NH4 and NO3 increased. 45 genera belongs to 4 phyla of phytoplankton as follows: Chrysophyta, Chlorophyta, Euglenophyta and Cyanophyta. Zooplankton existing in this river belong to animal classes, which had more abundance in Sarcodina and Monogononta. The benthos river establish Insecta larvae of Ephemeroptera, Coleoptera, Diptera, Plecoptera and Odonata (Orders). Chaloos fishes included to 4 families, 10 genera and 12 species. Cyprinidac consisted 66.7% of total fish and had maximum diversity at the various stations

    A tile model of circuit topology for self-entangled biopolymers

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    Building on the theory of circuit topology for intra-chain contacts in entangled proteins, we introduce tiles as a way to rigorously model local entanglements which are held in place by molecular forces. We develop operations that combine tiles so that entangled chains can be represented by algebraic expressions. Then we use our model to show that the only knot types that such entangled chains can have are 3(1), 4(1), 5(1), 5(2), 6(1), 6(2), 6(3), 7(7), 8(12) and connected sums of these knots. This includes all proteins knots that have thus far been identified.Pharmacolog

    Topical application of silymarin enhances cutaneous wound healing in rats

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    Abstract Wound healing in a short period with minimum side effects is one of the major goals of medical sciences. Silymarin, an extract from Silybum marianum, has been shown to have antioxidant and anti-inflammatory properties. This study investigates the wound healing activity of silymarin topical formulation in an in experimental model. A 875 mm2 (25 × 35 mm) full-thickness excision was made on the abdominal region of each rat by a surgical blade and the day on which the wound was made considered as day 0. Each rat was treated two times each day. On days 1,4, 8 and 12, the wound area was measured using precise caliber and camera imaging. On day 12, blood samples were collected for the analysis of antioxidant, malondialdehyde and estradiol levels. After 12 days of treatment, rats were sacrificed and abdominal region tissues used for histological analyses. The study showed that topical application of silymarin on wound in rats improved wound healing correlating with less redness, exudates and swelling. Furthermore, in serum of rats treated with silymarin ointment improved antioxidant and estradiol levels, while decreased malondialdehyde levels, a marker of oxidative stress. Histological analyses showed also an improve of novel blood vessels. This effect on angiogenesis correlated with improve nitric oxide synthase expression and epithelial cells after treatment with silymarin. Silymarin ointment represents a promising therapeutic agent for the treatment of wounds through its antioxidant and anti-inflammatory properties

    Comparison of statistical downscaling methods for climate change impact analysis on precipitation-driven drought

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    General circulation models (GCMs) are the primary tools for evaluating the possible impacts of climate change; however, their results are coarse in temporal and spatial dimensions. In addition, they often show systematic biases compared to observations. Downscaling and bias correction of climate model outputs is thus required for local applications. Apart from the computationally intensive strategy of dynamical downscaling, statistical downscaling offers a relatively straightforward solution by establishing relationships between small- and large-scale variables. This study compares four statistical downscaling methods of bias correction (BC), the change factor of mean (CFM), quantile perturbation (QP) and an event-based weather generator (WG) to assess climate change impact on drought by the end of the 21st century (2071–2100) relative to a baseline period of 1971–2000 for the weather station of Uccle located in Belgium. A set of drought-related aspects is analysed, i.e. dry day frequency, dry spell duration and total precipitation. The downscaling is applied to a 28-member ensemble of Coupled Model Intercomparison Project Phase 6 (CMIP6) GCMs, each forced by four future scenarios of SSP1–2.6, SSP2–4.5, SSP3–7.0 and SSP5–8.5. A 25-member ensemble of CanESM5 GCM is also used to assess the significance of the climate change signals in comparison to the internal variability in the climate. A performance comparison of the downscaling methods reveals that the QP method outperforms the others in reproducing the magnitude and monthly pattern of the observed indicators. While all methods show a good agreement on downscaling total precipitation, their results differ quite largely for the frequency and length of dry spells. Using the downscaling methods, dry day frequency is projected to increase significantly in the summer months, with a relative change of up to 19 % for SSP5–8.5. At the same time, total precipitation is projected to decrease significantly by up to 33 % in these months. Total precipitation also significantly increases in winter, as it is driven by a significant intensification of extreme precipitation rather than a dry day frequency change. Lastly, extreme dry spells are projected to increase in length by up to 9 %.</p
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