Assessment of Workers' Exposure to Cement Dust, in Concrete Batching Unit of a Dam Project before and after Control Measures

Background: The importance of clean air in industrial workplaces is well known. Cement dust, due to its silica content, is very dangerous. The aims of this study were to assess and control the release of cement dust from silos of concrete batching units during charging and production processes in a dam project. Methods: In this study, dust particule mass released from the cement silos were investigated by performing environmental samplingandpersonal sampling from 15 operators of batching machine. Samples were analyzed by gravimetric method. Control methods were used to control the released dust. Data collected before and after the intervention were analyzed through SPSS19 and using paired t- test and one sample t- test. Results: Mean concentrations of dust particles masses in personal and environmental samples were respectively 15.56 and 30.77mg/m3 and both were higher than the standard exposure limit values in Iran. After implementation of dust control methods, mean concentrations of dust in personal and environmental samples decreased respectively to 4.1 and 5.2 mg/m3 that show the efficiency of control methods. Conclusion: The control method applied in the present study is a novel and cost-effective method to control the released particles from batching units of cement silos. It is possible to decrease the dust concentration in industrial workplaces to the standard levels, by performing simiar methods. Keywords: Dust, Cement, Batching Silo, Dam Constructio

Chronic disease program in Iran: Thalassemia control program

BACKGROUND: β-thalassemias (beta-thalassemia) is the most common genetic disorder; it is an inherited globinopathy which is transmitted to people due to a mutation in genes that create globin chain. In Iran, the disease gene is more common in the northern and southern regions. It is estimated that more than 60 mutations of the disease exist in different geographical areas of Iran. Iran has begun to adopt strategies to control the β-thalassemia for two decades; the most important of which is the screening of couples when they want to get marry. The present study aimed to review the thalassemia control program in Iran, the history of the disease, and the disease control strategies. METHODS: This review was conducted according to hand and electronic resources. Books, guidelines and document that exist in thalassemia control program were reviewed in the Iranian Ministry of Health, World Health Organization resources, PubMed, Google Scholar, SID (scientific information database), Magiran and, Iranmedex. RESULTS: Thalassemia program was appropriately structured and has been achieved successes. Reduction the numbers of new cases of β-thalassemia were notably. In some areas, thalassemia program has some defects and the program faced some cultural barriers. CONCLUSION: Due to the improvements in the social and economic situation of the people, it seems necessary to focus on prenatal diagnosis (PND) and pre-implantation genetic diagnosis (PNG) technique strategies and provide their necessary facilities

The common fixed point of single-valued generalized φf-weakly contractive mappings

AbstractFixed point and coincidence results are presented for single-valued generalized φf-weakly contractive mappings on complete metric spaces (X,d), where φ:[0,∞)→[0,∞) is a lower semicontinuous function with φ(0)=0 and φ(t)>0 for all t>0 and f:E→X is a function such that E⊆X is nonempty and closed. Our results extend previous results given by Rhoades (2001) [1] and by Zhang and Song (2009) [2]

Strategic and Stochastic Approaches to Modeling the Structure of Multi-Layer and Interdependent Networks

Examples of complex networks abound in both the natural world (e.g., ecological, social and economic systems), and in engineered applications (e.g., the Internet, the power grid, etc.). The topological structure of such networks plays a fundamental role in their functioning, dictating properties such as the speed of information diffusion, the influence of powerful or vulnerable nodes, and the ability of the nodes to take collective actions. There are two main schools of thought for investigating the structure of complex networks. Early research on this topic primarily adopted a stochastic perspective, postulating that the links between nodes are formed randomly. In an alternative perspective, it has been argued that optimization (rather than pure randomness) plays a key role in network formation. In such settings, edges are formed strategically (either by a designer or by the nodes themselves) in order to maximize certain utility functions. The classical literature on the structure of networks has predominantly focused on single layer networks where there is a single set of edges between nodes. However, there is an increasing realization that many real-world networks have either multi-layer or interdependent structure. While the former considers multiple layers of relationships between the same set of nodes, the latter deals with networks-of-networks consisting of interdependencies between different subnetworks. This thesis focuses on the analysis of the structure of multi-layer and interdependent networks via strategic and stochastic approaches. In the strategic multi-layer network formation setting, each layer represents a different type of relationship between the nodes and is designed to maximize some utility that depends on its own topology and those of the other layers. By viewing the designer of each layer as a player in a multi-layer network formation game, we show that hub-and-spoke networks that are commonly observed in transportation systems arise as a Nash equilibrium. Extending this analysis to interdependent networks where there are different sets of nodes, we introduce a network design game where the objective of the players is to design the interconnections between the nodes of two different networks, G1 and G2. In this game, each player is associated with a node in G1 and has functional dependencies on certain nodes in G2. Besides showing that finding a best response of a player is NP-hard and characterizing some useful properties of the best response actions of the players, we prove existence of pure Nash equilibria in this game under certain conditions. In order to obtain further insights into the structure of interdependent networks with an arbitrary number of subnetworks, we consider a model for random interdependent networks where each edge between two different subnetworks is formed with probability p. We investigate certain spectral and structural properties of such networks, with corresponding implications for certain variants of consensus dynamics on those networks. In particular, we study a property known as r-robustness, which is a strong indicator of the ability of a network, including interdependent networks, to tolerate structural perturbations and dynamical attacks

The effects of different levels of vitamin-E and organic selenium on performance and immune response of laying hens

The aim of this study was to determine the effects of different vitamin-E and organic selenium (selenomethionine) levels on performance and immune response of laying hens. A total of 270 laying hens (65-weeks old Lohman-LSL Lite) were assigned to nine experimental diets consisting of nine replicates (cage) and six hens per cage. A 3×3 factorial arrangement including three levels of vitamin E (0, 125 and 250 mg/kg diet from α-tocopherol acetate) and three levels selenium (0.0, 0.50 and 0.75 mg/kg diet from selenomethionine) was employed for six weeks trial period. The hens performance including hen-day egg production%, feed intake, egg mass (g/hen/day) and feed conversion ratio (FCR, g feed: g egg) were measured. Antibody production against sheep red blood cells (SRBC) also was measured. The general linear model procedure of SAS software was used for data analysis and differences among treatment means was determined using the Duncan’s multiple-range test. The results show that the inclusion of vitamin E and selenium had a significant effect on production performance of laying hens (P<0.05). In addition, vitamin E and selenium supplements improved immune response of laying hens and a more positive effect was observed when 0.75 mg/kg selenium and 250 mg/kg vitamin E was added to the diet. From the results of the present study, it could be concluded that utilization of organic selenium plus vitamin E in diets was effective for improving the performance and immune system of laying hens.Keywords: Vitamin-E, selenomethionine, laying hen, performance, immune system.<brAfrican Journal of Biotechnology Vol. 12(24), pp. 3884-389