277 research outputs found

    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

    Piezoelectric Property of Electrospun PVDF Nanofibers as Linking Tips of Artificial-Hair-Cell Structures in Cochlea

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    This is the final version. Available from MDPI via the DOI in this record. The death of hair cells and damage of natural tip links is one of the main causes of hearing-loss disability, and the development of an advanced artificial hearing aid holds the key to assisting those suffering from hearing loss. This study demonstrates the potential of using electrospun polyvinylidene fluoride (PVDF) fibers to serve as the artificial tip links, for long-term hearing-aid-device development based on their piezoelectric properties. We have shown that the electrospun PVDF-fiber web, consisting of fibers ranging from 30-220 nm in diameter with high β-phase content, possesses the high piezoresponse of 170 mV. Analyses based on combined characterization methods including SEM, TEM, XRD, FTIR, Raman, DSC, XPS, PFM and piezoelectricity have confirmed that an optimized value of 15 wt.% PVDF could act as an effective candidate for a tip-link connector in a vibration-frequency prototype. Based on this easily reproducible electrospinning technique and the multifunctionalities of the resulting PVDF fibers, this fundamental study may shed light on the bio-inspired design of artificial, self-powered, high performance, hair-cell-like sensors in cochlea to tackle the hearing loss issue.Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Council (EPSRC

    Physico-chemical parameters and aquatic investigation in Tajan River and identification of effects on destroytion its

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    This project was carried out for one year in 1994-1995. Tajan River originated from Alborz Mountain and passes from sari city, and then entered into Caspian Sea. In this study 14 physical and chemical factors surveyed. This survey demonstrated that water quality in milk factory and kilka factory was more than standard. With utilization of water in agriculture period and dry of river, caused to increasing of chloride, total hardness, Ca^++, Mg^++ in estuary. This issue obtained to mixture of fresh water and saline water in estuary. In the survey of the river phytoplankton, 92 species identified that belong to 41 genus and five phyla. The Chrysophyta has more variation and density. Zoo plankton of river included in Protozoa, Rotaria, Cladocera and Copepoda, also the meroplankton such as Lamellibanchiate and Cirripedia observed. The high species variation is relative to protozoa but copepoda has high density and biomass. The five classes of zoobenthos observed in Tajan river such as Bivalvia, Crustacea, Arachnoids, Oligochaeta and insecta. The insecta class has six order and 22 families that Diptera order from insecta class has high variation. The river fishes are belonging to 23 species, 18 genus and eight families. The highest variation observed in station 4 in estuary that 17 species identified in this area. Ths seasonal stations situated in tributary river, station 5 (Zarem rood) has high variation and station 7 (Khormabad river) has important for salmo truta fario habitat

    Ecological study on fisheries important rivers and bays in the south part of the Caspian Sea 2nd phase: Gorgan Bay

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    In this study ichthyoplankton, phytoplankton, zooplankton, benthic and hydrochemistry parameters were studied. 9 out of 11 sampling stations were in the Gorgan Bay area and 2 of them were in the mouth of the Bay. Ichthyoplankton survey were carried out in 6 stations and the other surveys such as phytoplankton, etc were done in 11 stations in 2009. Gorgan Bay map and position of sampling sites are given at the end of material and methods section. Biomass and frequency of phytoplankton at different stations, months and seasons were calculated that are presented in Tables 1 to 3. Hydro-chemical parameters such as water temperature, air temperature, visibility, DO, BOD5, pH, Alkalinity (bicarbonate, carbonate and total), Hardness (calcium, magnesium), CL,EC, Salinity, N (nitrate, nitrite, NH_3), Phosphate were measured and results are shown Table 11. Biomass (mgr/m^3) and numbers (ind./m^3) of 47 genus of different phylum of phytoplanktons such as Cyanophyta, Chlorophyta, Pyrophyta, Chrysophyta and Euglenaphyta as well as different phylum of zooplanktons consist of Protozoa, Arthropoda, Rotifera and Cyliophora were estimated. Frequency of phytoplanktons (ind/m^3) was 131.2, 1.6, 65.3, 18.9 and 23.8 million respectively. Furthermore, their biomass was 308.4, 1.9, 1358.9, 295.1 and 124.7 mg/m^3, respectively. The maximum and minimum numbers were observed in Leptolingbaya belonged to Cyanophyta and Diatoms of Chrysophyta 84.3 and 0.025 million (ind/ m^3) respectively. The maximum and minimum biomass was observed in Gyrosigma (Chrysophyta) and Tetradron (Chloropyta), 12317.3 and 0.014 mg/m3 respectively. The average biomass of zooplankton was measured 531.74, 30.77, 225.07, and 96.26 mg/m^3 respectively and the total was attained 883.83 mg/m3 Table 5. The maximum and minimum biomass of all zooplanktons was estimated in November and July, 3446.23 and 6 mg/m^3 respectively. Furthermore, the maximum and minimum numbers of zooplanktons were found in September and July which were 48.4 and 0.002 millions respectively and the average number was 8.4 ind/m^3 Table 4. Also numbers and biomass (gr/m^2) of 11 families of benthos which inhabit Gorgan Bay such as Annelida, Mollusca and Arthropoda were investigated in separated stations and distinctive months. The maximum and minimum biomass of benthos was observed in January (42.91 gr/m^2) and March (0.6428 gr/m^2). The biomass was considerable in April, February, August and December (Tables: 4, 5 and 6)

    Impact of maternal education on response to lifestyle interventions to reduce gestational weight gain: Individual participant data meta-Analysis

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    Objectives To identify if maternal educational attainment is a prognostic factor for gestational weight gain (GWG), and to determine the differential effects of lifestyle interventions (diet based, physical activity based or mixed approach) on GWG, stratified by educational attainment. Design Individual participant data meta-Analysis using the previously established International Weight Management in Pregnancy (i-WIP) Collaborative Group database (https://iwipgroup.wixsite.com/collaboration). Preferred Reporting Items for Systematic reviews and Meta-Analysis of Individual Participant Data Statement guidelines were followed. Data sources Major electronic databases, from inception to February 2017. Eligibility criteria Randomised controlled trials on diet and physical activity-based interventions in pregnancy. Maternal educational attainment was required for inclusion and was categorised as higher education ( 65tertiary) or lower education ( 64secondary). Risk of bias Cochrane risk of bias tool was used. Data synthesis Principle measures of effect were OR and regression coefficient. Results Of the 36 randomised controlled trials in the i-WIP database, 21 trials and 5183 pregnant women were included. Women with lower educational attainment had an increased risk of excessive (OR 1.182; 95% CI 1.008 to 1.385, p =0.039) and inadequate weight gain (OR 1.284; 95% CI 1.045 to 1.577, p =0.017). Among women with lower education, diet basedinterventions reduced risk of excessive weight gain (OR 0.515; 95% CI 0.339 to 0.785, p = 0.002) and inadequate weight gain (OR 0.504; 95% CI 0.288 to 0.884, p=0.017), and reduced kg/week gain (B-0.055; 95% CI-0.098 to-0.012, p=0.012). Mixed interventions reduced risk of excessive weight gain for women with lower education (OR 0.735; 95% CI 0.561 to 0.963, p=0.026). Among women with high education, diet based interventions reduced risk of excessive weight gain (OR 0.609; 95% CI 0.437 to 0.849, p=0.003), and mixed interventions reduced kg/week gain (B-0.053; 95% CI-0.069 to-0.037,p<0.001). Physical activity based interventions did not impact GWG when stratified by education. Conclusions Pregnant women with lower education are at an increased risk of excessive and inadequate GWG. Diet based interventions seem the most appropriate choice for these women, and additional support through mixed interventions may also be beneficial

    Climate variability impact on the spatiotemporal characteristics of drought and aridity in arid and semi-arid regions

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    Investigating the spatiotemporal distribution of climate data and their impact on the allocation of the regional aridity and meteorological drought, particularly in semi-arid and arid climate, it is critical to evaluate the climate variability effect and propose sufficient adaptation strategies. The coefficient of variation, precipitation concentration index and anomaly index were used to evaluate the climate variability, while the Mann-Kendall and Sen’s slope were applied for trend analysis, together with homogeneity tests. The aridity was evaluated using the alpha form of the reconnaissance drought index (Mohammed & Scholz, Water Resour Manag 31(1):531–538, 2017c), whereas drought episodes were predicted by applying three of the commonly used meteorological drought indices, which are the standardised reconnaissance drought index, standardized precipitation index and standardized precipitation evapotranspiration index. The Upper Zab River Basin (UZRB), which is located in the northern part of Iraq and covers a high range of climate variability, has been considered as an illustrative basin for arid and semi-arid climatic conditions. There were general increasing trends in average temperature and potential evapotranspiration and decreasing trends in precipitation from the upstream to the downstream of the UZRB. The long-term analysis of climate data indicates that the number of dry years has temporally risen and the basin has experienced succeeding years of drought, particularly after 1994/1995. There was a potential link between drought, aridity and climate variability. Pettitt’s, SNHT, Buishand’s and von Neumann’s homogeneity test results demonstrated that there is an evident alteration in the mean of the drought and aridity between the pre- and post-alteration point (1994)

    Fabrication of arrays of lead zirconate titanate (PZT) nanodots via block copolymer self-assembly

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    This Article presents a simple methodology for the fabrication of two-dimensional arrays of lead zirconate titanate (PZT) nanodots on n-doped Si substrates via the directed self-assembly of PS-b-PEO block copolymer templates. The approach produces highly ordered PZT nanodot patterns, with lateral widths and heights as small as 20 and 10 nm, respectively, and a coverage density as high as ∼68 × 109 nanodots cm–2. The existence of a perovskite phase in the nanodots was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The piezo-amplitude and ferroelectric domain response obtained from the nanodots, through piezoresponse force microscopy, confirmed the presence of ferroelectricity in the PZT arrays. Notably, PZT nanodots with a thickness ∼10 nm, which is close to the critical size limit of PZT, showed ferroelectric behavior. The presence of a multi-a/c domain structure in the nanodots was attributed to their polycrystalline nature
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