Background: Manganese (Mn) is an essential element for the human body, but it can cause adverse effects on the Central Nervous System at high doses. Exposure to manganese fumes during welding can harm welders' health. Objectives: The current study aimed to measure manganese produced by shielded metal arc welding (SMAW) in the breathing zone air and blood of welders and investigate the relationship between manganese concentrations in air and blood. Methods: In this descriptive-analytical cross-sectional study, 35 welders were enrolled as the exposed group and 40 office workers as the control group. Manganese concentration in air was measured according to NIOSH method 7301. Air and blood sample analyses were carried out by ICP-OES. Statistical analysis was performed with MINITAB 17. Data were analyzed using Pearson correlation coefficient, one-sample t-test, paired t-test, and logistic regression. The significance level was set at P < 0. 05. Result: The mean concentration of welding respirable particles and manganese fumes were 9. 56-1. 67 and 0. 45-0. 08 mg/m, three and 22 times the exposure limit recommended by ACGIH, respectively. Average manganese was significantly higher in the welders' blood (0. 16-0. 02 , g/mL) than in the controls' blood (0. 04-0. 002 , g/mL). There were strong and significant correlations between the welding respirable particles and manganese concentration in welders' breathing zone and blood manganese levels. Also, with each year of work experience, the manganese concentration in the welders' blood increased by 1. 5%. Conclusions: Welders are at risk of contamination with manganese. Manganese exposure reduction through more efficient ventilation systems, reducing welder's exposure time, staff training, and appropriate respiratory protection equipment should be applied to reduce manganese exposure among welders and prevent health complications.

Background and aims: Manganese (Mn) is an essential element for human body, but over exposure to Mn can cause adverse effects especially neurotoxicity. Biological monitoring plays an important role in occupational exposure assessment. The aim of present study was to assess Manganese-Iron Ratio (MIR) as a potential biomarker for manganese. Methods: This cross-sectional study was carried out in an automotive parts manufacturing industry in Tehran, Iran. 31 ferroalloy smelters as exposed group (cases) and 30 office workers as unexposed control group were involved in the study. Occupational exposure to manganese was determined based on NIOSH analytical method 7300. Air and blood samples were analyzed using furnace-atomic absorption spectroscopy (GF-AAS). Serum Iron was measured according to Iron-Ferrozine LS. Statistical analysis was performed using SPSS software. Results: The mean concentration of air Mn for smelter group was 0. 008± 0. 005 mg/m3. The mean manganese concentration in blood samples of smelter group (17. 33 ± 8. 66μ g/L) was significantly higher than in the control group (9. 37 ± 8. 70μ g/L), (p< 0. 05). Also, the mean value of MIR in the smelter group was significantly higher than in the control group (p< 0. 05). Correlation test showed significant relationship between air manganese and MIR (p< 0. 05, r=0. 426). Conclusion: Manganese-Iron Ratio can be used as a biomarker to distinguish manganese exposed workers from the unexposed population.

A significant portion of manganese (Mn) chemical fertilizers applied to calcareous soils is not absorbed by the first crop and may, therefore, affect the growth as well as chemical composition of the subsequent crops, this being called the residual effect of Mn, Soil tests may be employed to predict such effects. The present experiment was conducted to study the residual effects of manganese sulfate on the subsequent crop of soybean (Glycine max L.). Twenty soils of northern Iran (5-39% calcium carbonate equivalent), previously treated with two levels of Mn (0 and 30 mg Mn kg-1 as MnSO4) and under a single crop of soybean, was used in greenhouse to grow a second subsequent crop of soybean with no additional Mn fertilizer but with a uniform application of nitrogen, phosphorous and potassium. Soils were sampled before the subsequent crop and extracted through Mn extractant DTPA. Dry weight of plant tops as well as Mn concentration and uptake after eight weeks under the greenhouse conditions were used as the plant responses to residual Mn in soil. Statistical analyses showed that manganese sulphate application significantly increased the dry matter from 16.56 to 20.29 g/pot. Manganese application also increased leaves' Mn content as well as Mn uptake from 115 to 120.20 mg/kg vs. from 1.98 to 2.45 mg/ pot., respectively. The overall effects of previously applied Mn on dry matter were not significant, whereas seed yield, as well as Mn uptake were significantly increased. In all the soils, grain yield increased by 7.67% in comparison with control. The residual effects of Mn on dry matter and seed yield of the third crop on these soils were non-significant, but Mn uptake increased by 8.19% in comparison with control. In the fourth crop, the residual effects of Mn on dry matter , seed yield , Mn concentration and Mn uptake were found to be of no significance.

In this study, in order to investigate the effect of increasing the manganese content on microstructure and mechanical properties of high manganese austenitic steels, three alloys with successive increases in weight percentages of manganese (7.55, 13.1, and 16.5) and carbon (0.8 and 1.2) were cast in the presence of a constant amount of chromium (1.5 wt.%) and silica (0.6 wt.%). The samples experienced solution annealing heat treatment comprised of austenitizing at 1100°C for 2 h followed by rapid quenching in stirred water. Hardness, tensile, and wear tests were conducted by dry sand/rubber-wheel abrasion method. Microstructural observations were performed by using optical (OM) and scanning electron microscopies (SEM) and energy dispersive spectroscopy (EDS). The obtained results revealed that after heat treatment a uniform austenite structure has developed in all three samples. With the increase of weight percent of the elements from sample 1 to sample 3, the hardness value reaches from 191 to 218 Vickers. Also, with the increase of manganese weight percent from 7.55 to 16.5, the ultimate tensile strength and wear resistance showed 11% and 29% increase, respectively, to the effect that the most enhanced mechanical properties and maximum wear resistance were observed in sample 3 with 16.5wt % of manganese. This improvement in mechanical properties and wear resistance is related to the formation of the solid solution in the matrix, the increase of hardenability, and the increase of work hardening capacity resulted from the increase of manganese percentage. Examination of the abraded surfaces demonstrated that the involved wear mechanism was scratch wear mechanism.

AbstractIntroduction: Manganese oxide nanoparticles are used as strategic materials in various industries such as battery manufacturing, water and wastewater treatment, pharmaceutical industries, etc. because of economic reasons and have special physical and chemical properties. The production of manganese oxide nanoparticles is one of the secondary metabolites in bacteria. Considering that the manganese and narcissus mine in Qom province is one of the most important sources of manganese for manganese-oxidizing microorganisms, this project was done for the first time on mine soli.Materials and Methods: In this study, 100 soil samples were collected from different areas of the manganese mine and inoculated in the selective enrichment medium K and heated on a rotary shaker. The strains obtained from the culture in a manganese-containing medium were evaluated by the benzidine test to evaluate the oxidation ability of manganese and properties of manganese oxide nanoparticles including morphology, size, and chemical structure using confirmation techniques such as UV-VIS, FTIR, XRD, FESEM, TEM. Using the FESEM histogram, the size of nanoparticles in the range of 10 nm was determined and the selected strain was molecularly identified.Results: For the first time, native actinobacteria strain with the ability to oxidize manganese and nanoparticle production extracellularly was isolated from the Venarj manganese mine soil of Qom and was biochemically and molecularly identified. The strain was registered in the NCBI with the name Streptomyces xantholiticus HA98 and identification code OM669940.Discussion and Conclusion: Based on the importance of manganese oxide nanoparticles in medical, industrial, and pharmaceutical industries and that the Venarj manganese mine soil of Qom is an important source for manganese-oxidizing microorganisms, the present study was conducted for the first time in Iran on this mine soil so that the microorganism with the above properties could be identified and used in various industries

Background: In present study, chronic exposure to manganese (Mn) and its effect on blood iron (Fe) indices in miners of Iran manganese mines-Qom have been investigated.Methods: In this cross-sectional study, fifty six miners and 5 control persons were studied cross sectionally. Prior to beginning of daily work, miners filed questionnaire and then their blood, urine and saliva samples were collected. Mn concentrations in samples were analyzed by atomic absorption spectroscopy (AAS). CBC analysis was performed by auto-analyzer system and blood Fe, transferrin (Tf), ferritin (Fr), total iron binding capacity (TIBC) and hemoglobin (Hb) were determined by respected commercial kits. Results processed by using software SPSS 16.Results: Between measured indices, only blood Mn, Fe and TIBC had significant difference in miners and controls (P<0.05). The results showed that although Mn and Fe level increased in serum of miners but did not cause anemia. Result even the maximum manganese of blood, 1580g/L has not had undesired effects on miners iron homeostasis.Conclusions: Therefore Mnmining and Mnaccumulation in blood did not increase the risk of impaired iron homeostasis. This may be due to co-exposure to Fe (in braunite (Mn mineral)) and/or compensatory mechanisms that don’t allow to wide range changes in blood parameters. Also personal discrepancy, social status, life style and place may influence the results of present study.

In this study, a new and inexpensive polymeric sensor was developed for determination of Manganese in the aqueous media. The scanometric method was used to measure the color intensities of each polymeric film. In the scanometry, the image of films were transferred into image analyzing software. In the software any spots of the film were analyzed to red, green, and blue color parameters. For the preparation of polymeric manganese sensor film, triacetylcellulose was chosen as substrate and by using the activation process, Brilliant Cresyl Blue stabilized on inexpensive polymer substrate. After the polymer film made quite active, the experimental parameters including film response time, range of pH, concentration of brilliant cresyl blue was optimized. In this study, linear range and sensitivity of polymeric sensor film for all color parameters were obtained. Maximum linear range was obtained for red and blue (equal) and minimum linear range was obtained for green paremeter. Also, the green parameter had maximum sensitivity in the films.