31 research outputs found

    Cure Rate Following Rejection in Bilateral Corneal Grafts for Keratoconus

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    Purpose: To estimate cure rate following graft rejection in bilateral corneal transplants in Iranian patients with keratoconus and to determine risk factors associated with rejection. Methods: In this retrospective study, data were compiled from records of patients who had undergone bilateral penetrating keratoplasty (PK) for keratoconus between 1988 and 2007. In order to estimate cure rate in patients with and without corneal vascularization, we adopted the cure rate frailty model with a Bayesian approach. Results: Two hundred and thirty-eight eyes of 119 patients underwent bilateral corneal transplantion for keratoconus, of which 22.7% experienced graft rejections. Cure rates for patients with and without corneal vascularization were 41% and 79%, respectively. Cure rate decreased 12% per decade of increase in recipient age. The 1, 5, and 10-year survival of corneal transplants without any graft rejection episodes were 82%, 74%, and 70% respectively. Conclusion: The most important risk factor predisposing to rejection in patients undergoing bilateral PK for keratoconus was corneal vascularization. Cure rate for patients without vascularization was high in this data set, indicating that penetrating keratoplasty in keratoconus patients without vascularization is an efficient and reliable procedure

    Improving Phosphorus Availability and Wheat Yield in Saline Soil of the Lake Urmia Basin through Enriched Biochar and Microbial Inoculation

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    To reduce requirements for conventional chemical fertilizer and alleviate salinity stress in soils, a glasshouse experiment was conducted to assess the effects of enriched biochar on phosphatase activity, microbial respiration and wheat yield in non-saline and saline soils from the Lake Urmia basin (electrical conductivities 2 dS.m(-1) and 15 dS.m(-1), respectively). Nine treatments were tested: control, 1:1 mixture of apple and grape biochars (BC), phosphate solubilizing bacteria (PSB), BC plus PSB (BC-PSB), BC plus rock phosphate (BC-RP), BC enriched by rock phosphate and bacteria (BC-RP-PSB), BC enriched by rock phosphate and HCl (BC-RP-HCl) or H3PO4 (BC-RP-H3PO4) and chemical fertilizer (TSP). The addition of enriched biochar decreased the soil pH (by 0.5-0.9 units) and increased available phosphorus (>7-fold). In both the saline and non-saline soils, the highest alkaline phosphatase activity was obtained for BC-H3PO4-RP and BC-HCl-RP. Wheat growth parameters were reclaimed after enriched biochar application, indicating superior dry matter yields compared to the control and non-enriched biochar treatments and significantly higher yields compared to TSP. Beneficial effects on soil pH, phosphatase activity, soil respiration and biomass yield demonstrated that enriched biochar could partly substitute chemical fertilizers and increase plant growth in salt stress conditions. However, further field studies are needed to understand the benefits of enriched biochar in different soils and climates

    Adsorption of Copper from aqueous solution by chitosan using molecular imprinting technology

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    In nature chitosan is a plentiful polymer with high heavy metal ion uptake capacity due to chitosan’s functional groups that chelate with the positive surfaces of heavy metal ions. In this study, epichlorohydrin was used as a crosslink to prepare the copper-imprinted chitosan as a pattern to enable the selectivity property and increase adsorption capacity. The effects of the cross-linker, PH, initial concentration and time were examined in this study to identify the optimum amount of each to remove copper metal ions from waste water by imprinted chitosan. This composite was characterized by Fourier-transform infrared spectroscopy (FTIR) test to determine the existence of copper ions in chitosan crosslinked with epichlorohydrin. Scanning electron microscopy (SEM) tests were also done to compare the surfaces of crosslinked chitosan and the removal of copper by imprinted chitosan. PH adsorption was tested from 3 to 7 and the initial concentration and time investigated were between 10 and 100 mg/l and 0 and 120 minutes respectively. The maximum capacity to adsorb was found to be at PH 7, initial concentration of 100mg/l at 90 minutes with 0.1 gr chitosan. Ultimately, the maximum adsorbent amount achieved for effective Cu(II) removal was 74.37 mg/g

    Removal of cadmium (II) by graphene oxide-chitosan adsorbent from aqueous solution

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    Pollution has a negative influence on the environment and is necessary to eliminate from wastewater and aqueous solution. There are several adsorbents for removing the pollution, among them Graphene oxide and Chitosan are proper elements with great uptaking ability. In this investigation, graphene oxide surface was coated with chitosan paricles to remove the Cadmium (II) from aqueous solution. The impact of concentration, pH and time were studied to achieve the optimum conditions of adsorption. The adsorbent was analyzed by TEM, FT-IR, XRD, and SEM analysis. The outcomes presented that the adsorbent was prepared successfully. The concentration item was tested from 10 to 120 ppm. The pH and time items were studied from 3 to 8 value and from 5 to 140 minutes for eliminating cadmium (II) respectively. Freundlich and Langmuir's models was used and the pseudo-second-order was the best fitted kinetic model in this investigation. Conclusively, the maximum adsorption ability of the made adsorbent was achieved at 107.8 mg/g based on Langmuir isotherm

    Removal of cadmium (II) from aqueous solution by graphene oxid

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    Heavy metal ions are one of the principal contamination source and cause of difficulties in wastewater processing that requires being eliminated before discharging into the eco-system. Adsorption of cadmium (II) from an aqueous solution by graphene oxide has been considered. Recently, graphene oxide (GO) has taken a large amount of attention because of high mechanical strength and appropriate surface area that has provided to apply as strengthened materials, various oxygen functional groups on its surface and π-electron system. In this investigation, graphene oxide was employed as an effective and proper adsorbent for separating the cadmium (II) from aqueous solution. TEM, Raman, FT-IR, and SEM tests have been used for characterizing the graphene oxide. In the adsorption process, initial concentrations of aqueous solution examined from 20 to 100 mg/l; pH and contact time were investigated from 3 to 8 and 5 to 100 minutes respectively. Adsorption isotherm obeyed Langmuir, Freundlich, and Temkin that the maximum cadmium adsorption capacity has been taken from Langmuir fitting with 135.14 mg/g. Also, the kinetic considerations explained that the adsorption manner followed the pseudo-second-order kinetic model with R2. Thermodynamic investigations and parameters show the exothermic and spontaneous of adsorption

    Design of a Recommender System with Safe Driving Mode Based on State-of-Function Estimation in Electric Vehicle Drivetrains with Battery/Supercapacitor Hybrid Energy Storage System

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    The performance of electric vehicle (EV) drivetrains depends on the power capability of individual components, including the battery pack, motor drive, and electric motor. To ensure safety, maximum power must be limited by considering the constraint of the weakest component in the drivetrain. While there exists a large body of work that discusses state-of-power (SoP) estimation for individual components, there is no work that considers all the components’ limiting factors at once. Moreover, research on how to use these limits to adjust the performance at the system level has been rare. In this paper, the SoPs of the components are used to estimate the state-of-function (SoF) of the EV drivetrain. The SoF is defined as the maximum charge/discharge power that can be sourced and/or sunk by the drivetrain without violating the safety limits of its components. The component-level SoP estimations are fulfilled using several digital algorithms based on recursive least-squares (RLS) and Kalman filters (KFs), as well as by taking into account specific limiting conditions such as high driving altitude and ambient temperatures. An EV driven by a hybrid energy storage system based on a battery/supercapacitor, and a permanent-magnet synchronous motor is considered the use case. Based on the drivetrain SoF estimation, we propose two de-rating schemes to ensure that the drivetrain safety limits will be respected: adaptive cruise control and adaptive adjustment of pedal sensitivity. The de-rating schemes are introduced to a so-called recommender system that is implemented in MATLAB/STATEFLOW. The recommender system provides advisory feedback to the driver to switch to a different driving mode to ensure safety. The simulation results over a standard drive cycle using MATLAB/SIMULINK and STATEFLOW show the effectiveness of the proposed design at both component and system levels. The paper also proposes an implementation concept for the integration of the proposed recommender system into the advanced driver assistance system (ASAS)

    An effective Arc Fault Detection Approach for Smart Grid Solar Farms Using Rogowski Coil Sensor

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    Co-Estimation of Supercapacitor States and Parameters Considering Three-Branch Equivalent Circuit Model

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