The purpose of this study was to evaluate the adsorption of humic acid (HA) by amine-modified nanocellulose. At first, nanocellulose was synthesized by acid hydrolysis, and then was modified by N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane. In the next step, HA and amine-modified nanocellulose were incubated at different conditions (pH, incubation time, temperature, and concentration). Furthermore, we used molecular dynamic (MD) simulation for observation of adsorption at molecular scale. For this purpose, HA and amine-modified nanocellulose were prepared by HyperChem software (Hypercube, Inc., USA), and inserted in Ascalaph Designer 1.8.69 software. Once equilibrium was reached, interactions were simulated for 1,000 ps. Finally, different parameters such as interaction energy, potential energy, and root-mean-square displacement (RMSD) were measured. This study demonstrated that the adsorption of HA was pH-, temperature-, dose-, and time-dependent. Based on simulation results, the interaction energy was reduced, but potential energy and RMSD were increased at the final stage of simulation, which indicated the adsorption of HA. The authors suggest amine-modified nanocellulose for removal of HA in wastewater.
Introduction: work-related accidents impose irreparable hurt on the national capital. It is necessary to take a series of preventive measures before the occurrence to preserve and protect the human force and reduce accidents. The current study aimed to check safety contradiction using the FMEA method and determine protection indicators of safety performance in the overhaul project. Materials and Methods: This study is descriptive-analytical research and an interference method that accomplished 13 jobs in major repairs gas pipeline project. After determining jobs and entering them in the FMEA worksheet, the initial risk score was obtained in this investigation, and after corrective suggestions, the secondary risk priority score was calculated. Results: The relationship between RPN1 and RPN2 was examined and determined a significant difference between risk priority score before and after corrective measure, and this indicates that these measures are effective (p<0.0005). Among various jobs and before taking corrective actions, the highest number of accidents was related to excavation activities with 15 accidents, which were reduced to 6 after taking corrective measures. Most days lost from work were related to driving job with 6020 days that reduced to 8 days after taking corrective actions; the highest rate of repeat accidents with 62.5 was related to détente activity reduced to 23.14 after taking corrective measures. The maximum intensity factor with 19444.44 was related to the driving activity reduced to 25.25 after taking corrective actions. The accident frequency - severity rate in driving activity with 15.84 was the most reduced to 0.28 after taking corrective measures. Conclusion: Due to unacceptable risks and the high rate of accidents in the overhaul of the gas pipeline project, appropriate control measures can be used to reach an acceptable level of risk, which represents the usefulness of the FMEA method.
Introduction: Workload can be defined as the hypothetical construct that represents the cost incurred by a human operator to achieve a particular level of performance. Several methods have been used to assess the workload. One of the most common methods of assessing mental workload is NASA-TLX method. The present study was conducted to develop and validate of a pilot activity load index (PALI) based on NASA-TLX template. Materials and Methods: This study was a cross-sectional and descriptive-analytical that was carried out among airline pilots of Civil Aviation Organization. At first, “Pilot Activity Load Index” or PALI subscales were developed based on NASA-TLX template. Validity of the subscales was evaluated by Content Validity Ratio (CVR) and Content Validity Index (CVI).Using Lawshe’s table. Finally, to determine the internal consistency of the subscales, 30 pilots completed the final version of the PALI in typical flight phases. The data obtained were then analyzed by SPSS using Cronbach's alpha to measure the reliability of the subscales and considering an acceptance level of 0.7. Results: The first results led to the emergence of an initial list with 17 subscales. Eleven subscales were irrelevant, redundant and impractical to use in operational environment, due to CVR less than 0.75 and were omitted from the subscales list. Finally, six PALI subscales were approved related to pilot tasks (CVI=0.79). The Verified subscales had a Cronbach's alpha value of 0.89 and were therefore considered a reliable tool. Conclusion: The results of this study showed that PALI questionnaire which validity and reliability has been approved can be used for assessment of workload in pilots.
Introduction: Home accidents means accidents that happen in the house or its surroundings, and are the main cause of death and disability of children. Risk assessment is an organized method to identify, predict and reduce risk to an acceptable level. Therefore, our goal in this study is to identify and evaluate domestic hazards in the homes of Yazd city for children under seven years old. Methods and Materials: In this descriptive-analytical study, 322 home accidents were identified in a cluster method from different areas of Yazd city. Data were collected using a researcher-made questionnaire whose validity and reliability were measured by experts (α=0.764). After completing the questionnaires, the collected data were entered into SPSS software version 20 and were analyzed by descriptive tests, ANOVA and T-TEST in confidence level of 95% Results: The most injuries caused by hazards are cuts, bone fractures/dislocations and contusion with a frequency of 17%, 14.8%, and 9.6%, respectively. The highest risk assessment code belongs to minor risks with a frequency of 39.76%, and the lowest frequency is for critical risks (3.17%). There was a significant relationship between most of the risks in homes with the areas of Yazd city and the type of building (p-value<0.05). Conclusion: This study shows the importance of using from the risk assessment code method, which can be used to identify and determine the relative risk of hazards for each part of the house and provide prevention solutions based on priority. Also, by using appropriate training and policies to monitor compliance and full implementation of legal requirements in construction, home accidents and the resulting complications have been reduced, and safety culture and quality of life of families have been improved.
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