COF-43 based voltammetric sensor for Ag(I) determination: optimization of experimental conditions by Box-Behnken design.

Hydrazone-linked covalent organic framework-43 (COF-43) was synthesized and the carbon paste electrode (CPE) modified with this COF was used as a voltammetric sensor to measure silver(I). Various characterization tests (XRD, FTIR, BET, SEM/EDX, electrochemical impedance (EIS), and cyclic voltammetry (CV)) were performed on the synthesized COF-43 and the prepared COF-43/CPE. Box-Behnken design was used to optimize the preparation and operation conditions of the sensor. EIS and CV investigations reveal the diffusive characteristics of silver transport in the electrode matrix. An appropriate mechanism for the sensor procedure has been suggested and ratified by electrochemical and SEM/EDX techniques. The COF-43 used has several recognition elements for the selective binding of silver ion and due to its high porosity provides a large space for the deposition and reduction of large amounts of silver. Therefore, due to the correct selection of COF used in the construction of the sensor, high selectivity and sensitivity for the prepared sensor has been achieved. The obtained data disclosed that the modification of the carbon paste electrode by COF-43 significantly improves the analytical characteristics of the sensor, which specifies the performance of COF-43 as a sensory material for determining silver(I). The obtained calibration curve is linear in the concentration range from 0.001 µM to 10.0 µM and the detection limit is 1.5 × 10-10 M. Various statistical tests have been employed to evaluate the sensor performance. The appropriate accuracy and precision of the proposed method were confirmed using the analysis of variance (ANOVA) approach. Potential interferences were investigated and it was found that the other species did not have a significant effect on the sensor performance. The prepared sensor has been successfully used to measure silver in two samples of photographic effluents, bleaching, and fixing agents. The results from the analysis of real samples demonstrate the reliable applicability of the fabricated sensor.

Construction of a Tl(I) voltammetric sensor based on ZIF-67 nanocrystals: optimization of operational conditions via response surface design.

An electroanalytical sensor was constructed constituted on a carbon paste electrode (CPE) with a ZIF-67 modifier and devoted to the quantification of Tl(I). Several characterization tests including XRD, BET, FT-IR, SEM/EDS/mapping, TEM, impedance spectroscopy (EIS), and cyclic voltammetry (CV) were performed on the synthesized ZIF-67 nanocrystals and CPE matrix. Central composite design (CCD) was used to assess the impact of variables affecting the sensor response, including the weight percent of ZIF-67 (14%), the pH of the thallium accumulation solution (6.4), and accumulation time (315 s) as well as the accumulation potential (-1.2 V). The direct linear relationship between the sensor response and the concentration of Tl(I) is in the interval of 1.0×10-10 to 5.0×10-7 M (coefficient of determination = 0.9994). The detection limit is approximately 1.0 × 10-11 M. The right selection of the MOF makes this sensor highly resistant to the interference of other ions. High selectivity against common interferences in the measurement of thallium (such as Pb(II) and Cd(II)) is an important feature of this sensor. To confirm the performance of the prepared sensor, the amount of thallium in the real sample was determined.

A model of reopening businesses to decrease the heath and economic impacts of the COVID-19 pandemic: Lessons from Iran.

Background: OVID-19 is a major cause of morbidity and mortality worldwide. The closure of governmental and nongovernmental centers as well as social, cultural, and economic activities are other major negative impacts of the virus. The present paper aimed to develop a model of economic and health-related factors which affect the reopening of businesses and the proper management of the effect of virus on different aspects, particularly on people's health and economy. Methods: In order to facilitate decision-making and model risk analysis of guilds and occupations, an expert panel, including eight 8 experts, was convened by the Ministry of Health in Iran to prepare a strategic framework for the national taskforce of COVID-19 management. The panel spent many hours to prepare a simple model of reopening businesses and prioritize them from low to high risks. Results: The experts identified and weighed seven health and three economic-related factors. The businesses and jobs were classified into 69 categories based on their similarities; they were also graded according to a predefined five- point Likert scale and categorized into three levels of low, medium, and high risk. The policymakers recommended to reopen businesses stratified by risk levels at least two weeks' intervals. Conclusion: The relaunch strategy in Iran put health and safety first while gradually reopening businesses, resuming activities, and getting people back to work. At the same time, attempts were made to slow the spread of the virus through following public health measures, social distancing, good hygiene, and continued acting responsibly. As many countries may have to deal with the same issue, this model can help them adopt appropriate policies and strategies for disease containment.

Fabrication of an electrochemical sensor based on metal-organic framework ZIF-8 for quantitation of silver ions: optimizing experimental conditions using central composite design (CCD).

ZIF-8 was synthesized and carbon paste electrodes (CPEs) modified with this metal-organic framework were utilized for quantitation of silver(i) by the differential pulse anodic stripping voltammetry (DPASV) technique.Prepared ZIF-8 and the matrix of the electrodes were distinguished by impedance spectroscopy (EIS), XRD, FT-IR spectroscopy, cyclic voltammetry (CV), TEM and SEM/EDX methods. To obtain the strongest stripping peak currents, several significant variables were optimized with response surface methodology (RSM), including the ligand amount (near 11% w/w), applied potential for preconcentration (approximately -1.36 V), pH of the preconcentration solution (about 8.5) and preconcentration time (about 275 s). A calibration curve was acquired in the limits from 1.0 × 10-10 to 5.0 × 10-7 M with the Pearson correlation coefficient R = 0.9993. The limiting detectable concentration (LDC) was determined to be 1.0 × 10-11 M. The developed sensor has high selectivity for mercury(ii). The excellent pH, potential and especially size-exclusion based selectivity of the prepared sensor are unique characteristics that are very important in the determination of silver ions. The developed method was effectively employed for the quantitation of silver(i) ions in environmental and industrial samples.

Effectiveness of a primary health care program on urban and rural community disaster preparedness, Islamic Republic of Iran: a community intervention trial.

BACKGROUND: To evaluate the effectiveness of a capacity-building intervention administered through a primary health care (PHC) system on community disaster preparedness in Iran. METHODS: A controlled community intervention trial with pre- and postassessments was conducted in 2011 in 3 provinces of Iran. In each province, 2 areas were chosen and randomly selected as an intervention or control group. A total of 9200 households were in the intervention area and 10 010 were in the control area. In each study group in each province 250 households were sampled for pre- and postassessment surveys. Community health volunteers led by PHC staff administered an educational intervention covering elements of hazard awareness and preparedness, with a focus on earthquakes and floods. Relative changes for awareness and readiness scores were assessed to demonstrate changes in outcome variables from pre- to postassessments in intervention and control groups. An effectiveness test of significance was based on interaction between time and area. RESULTS: Households in intervention communities exhibited improved disaster awareness and readiness with respect to all outcome measures. Relative changes in awareness in intervention and control areas were 2.94 and -0.08, respectively (P < .001). Relative changes for readiness scores were 5.52 in intervention areas and 0.56 in control areas (P < .001). Relative changes for awareness and readiness were significantly correlated with a community's baseline risk perception and previous experience with natural disasters (P < .001). CONCLUSIONS: An educational intervention administered through the PHC system effectively improved disaster awareness and readiness at a community level. For sustainability, community disaster reduction programs must be integrated into routine public health service delivery.

Flash flood preparedness in Golestan province of Iran: a community intervention trial.

OBJECTIVE: To evaluate effectiveness of a community-based preparedness program for flash floods. DESIGN: A controlled community intervention trial with preassessment and postassessment. SETTING: Fifteen intervention villages and 16 control villages in Golestan province of Iran. PARTICIPANTS: People more than six years of age. INTERVENTION: Intervention program consisted assembling Village Disaster Taskforces (VDTs), training of VDTs and community, evacuation drill, and program monitoring. MAIN OUTCOME MEASURES: Individual participation in household preparedness actions including, preparedness meeting, risk mapping, preparation of emergency supplies, assisting vulnerable people, and evacuation drill. RESULTS: Our intervention improved preparedness of local community for flash floods in term of all interested outcome measures. For instance, adjusted odds ratio for participation in an evacuation drill in intervention area in postassessment compared with preassessment was 29.05 (95% confidence interval [CI]: 21.77-38.76), whereas in control area it was 2.69 (95% CI: 1.96-3.70). Difference in these odds ratios was statistically significant (p < 0.001). Participation in a family preparedness meeting and risk mapping were helpful in motivating individuals to take other preparedness actions. Women were found prepared as much as the men. Younger people showed lower participation in preparation of family emergency supplies but higher attendance in evacuation drills. Participation in evacuation drills decreased with increasing age. It was a positive association between risk perception and taking all preparedness actions. CONCLUSION: Flood preparedness programs should focus on participatory risk assessment and preparedness techniques, strive to improve risk perception and female capabilities, and ensure providing assistance to the older people during evacuation.

Evaluation of Golestan Province's Early Warning System for flash floods, Iran, 2006-7.

Golestan province located in NE Iran is well known for deadly flash floods. This study aimed to evaluate the region's Early Warning System (EWS) for flash floods. We used an adapted version of the questionnaire developed by the United Nations International Strategy for Disaster Reduction. We reviewed documents on the EWS of Golestan, and conducted a qualitative study comprising interviews with experts and affected people in Kalaleh and Minoodasht. Results were discussed by an expert panel. Regarding risk knowledge, there was a hazard map at Provincial Disaster Taskforce (PDT) drawn by the provincial Office for Water Resource Management, but no risk analysis was available. Local people were aware of their exposure to flooding, but not aware of the existence of a hazard map and their vulnerability situation. In terms of monitoring and warning, PDT faced serious limitations in issuing Early Warnings, including (1) an inability to make point predictions of rainfall, and (2) the absence of a warning threshold. Dissemination and communication issued by the Meteorological Office followed a top-to-bottom direction. The contents were neither clearly understood by other institutions nor reached the potential recipients within an appropriate time frame. There was a need for a comprehensive response plan with adequate exercises, and no evaluation framework existed. Golestan EWS is in dire need of improvement. To fill in the gaps ensuring local people receive timely warning, we propose a community-based model called "Village Disaster Taskforce" (VDT) in which individual villages act as operational units, but interlinked with other villages and PDT.