A Computational Study on the Configurational Behaviors of Dihalodiazenes and their Analogues Containing P and As Atoms

In this research, we report the results of DFT calculations using xc-hybrid functional, B3LYP and employ NBO interpretation to investigate the stereoelectronic effects. Electrostatic and steric impacts on the conformational properties of 1,2-difluorodiazene (1), 1,2-dichlorodiazene (2) and 1,2-dibromodiazene (3) are also studied. Factors determining the thermodynamically stable molecular structure of 1,2-dihalodiazenes and their analogues containing P and As atom are discussed, and the energetic effects of intra-molecular hyperconjugations and steric repulsion in each molecular system are theoretically estimated using NBO theory. The Energy components calculated help us to justify the conformational behaviour of our target compounds. One of the interesting features extracted from NBO analysis is that dissociation energies are controlled by the stabilization energies associated with electron delocalizations in these compounds. The main parameter considered in this study is the Gibbs free energy estimated for cis and trans configurations of compounds and for the cis-to-trans conversion through rotation and inversion mechanisms

Disaster relief operations: past, present and future

The aim of the preface is to introduce the scope of this special issue (SI). We explain our editorial approach and summarise our findings based on articles included in this SI. Finally, we outline future research questions which stemmed out of the discussions of this SI

Determination of pediatric poisoning factors in children

Background and Objective: Poisoning is a major public health problem and a serious form of the common causes of hospital emergency visits in many countries. Incidence of toxicity based on cultural and economic characteristics of communities are varied. This study was done to determine the pediatric poisoning factors in children. Methods: This descriptive-cross sectional study was performed on 201 patients younger than 12 years old with posinnig symptoms whom referred to hospitals in Shahroud city of central part of Iran from April 2011 to March 2012. Demogaphic data, posinnig symptoms, posinnig agents, time of hospitalization and outcome of posinnig for each child were recored in quetionare. Results: Opium was the most common consumed material with (51.2%) while metadon considered to be the major opium. 180 (89.6%) and 21 (10.4%) children were poisoned accidentaly by their parant respectively. The clinical manifestation of the affected children were 15 (7.5%), 11 (5.5%), 93 (46.3%), 26 (12.9%), 19 (2.5%) and 22 (10.9%) without any symptoms, neuro-respiratory, nervous, gastrointestinal, gastrointestinal-respriatory and weakness respectively. Two children were died in the course of this project. There was a significant statistical correlation between the reason for poisoning and age parant education level and type of poisoning. Also, there was a relation between the type of poisoning and place of residence (P<0.05). Conclusion: This study shows that the most common cause of poisoning among children was opiums

Effect of Monosodium glutamate on rat cerebellum

Background and Objective: Monosodium glutamate (MSG) is used as a food additive. Several studies have reported the adverse effects of Monosodium glutamate on the testis and brain. This study was performed to determine the effect of Monosodium glutamate in rat cerebellum. Methods: In this experimental study, 24 adult wistar rats randomly allocated into three groups including experiment A, experiment B and control (C). The animals in experiment A and B were received 3g and 6g of MSG thoroughly mixed with their feeds for 14 days, respectively. Animals in control group were received MSG free diet. Food and water for rats to be free in all of experimental time. The rats were sacrificed on fifteen day. The cerebellum dissected and fixed with formalin 10% buffer and stained with hematoxylin and eosin. Results: Disorders and detachment were observed in Purkinje and granular cell layers. Neural cell distribution in granular layer redeuced in the experimental groups. Cellular degenerative changes in the granular layer of the experimental B were more severe than experimental group A. The mean number of neuron of the granular layer in the experimental A, B and control groups were 2750, 2140 and 3150, respectively. Conclusion: The consumption of monosodium glutamate dose dependly causes histopathological changes and reduces the number of the cerebellumllar neurons in adult rat

Effect of mode of flocculation on flocs sedimentation behaviour in various regions of thickeners

Main portion of water in mineral processing plants is recovered in thickeners. The required surface area for thickeners is calculated based on the Coe and Clevenger theory where it is assumed, when no flocculants used, the settling velocity of particles in each layer in the free settling region is only a function of solids concentration in that layer. In this study, the effect of mode of flocculation, defined as the initial solids concentration where the floes first formed, on their settling velocity was investigated using batch settling tests. The pulps used for settling tests were prepared by two different methods to arrive at equal solids concentration. The methods were the standard procedure of adding solids to a known amount of liquid and decantation. The latter method made the change of mode of flocculation possible by decanting the dilute suspensions to obtain higher solids content pulps. Results of all settling tests (with and without flocculant) on copper, iron, lead and zinc ores, and coal suspensions showed that, unlike the Coe and Clevenger theory, the settling velocity of particles in any layer even in the free settling region is affected by solids content of the suspension where floes were first formed. For instance, the settling velocity of a layer of iron ore tailing with 22% solids in a flocculated (5 g/t) suspension varied from 1 .32 to 2. 73 em/min when the initial feed solids varied from 5 to 20%. Furthermore it was shown that the settling velocities of suspensions with equal solids content prepared by the two methods were different owing to the significant difference in their floes structures. It was concluded that the settling tests performed to determine the required surface area for thickening should be carried out etther on the single sample with the solids concentration of the thickener feed (after dilution if it is diluted) or on decanted samples. The conventional procedure of measuring settling velocities in various percent solids between the feed and the desired underflow is prone to large errors

Full pre-crush to sag mills – the case for changing this practice

The new practice of applying full pre-crushing of SAG mill feed to substantially increase throughput is challenged as retrogressive and inefficient at a time the industry desperately needs to reinvent itself in terms of social license and financial viability. Although successful, the impact on grind size, added downstream grinding and media consumption, and added OPEX is barely noted - providing a biased view of benefits. Alternatives that provide sound mineral processing routes, provide on-line mill control and are markedly cheaper to operate are presented as a potentially more viable and sensible route for both future installations and current expansions

Optimization of the design of AG mill shell liners at the Gol-E-Gohar concentration plant

One area in AG/SAG milling field which has received a great attention is the optimization of liner design for any application to increase the availability of mills. The Gol-E-Gohar iron ore concentration plant uses three 9m x 2.05m autogenous mills (AG) in parallel in a dry operation. The AG mill shell is lined with three series (57 em each) of 36-row liners. Due to large variations in feed characteristics and inadequate blending, the performance of AG mills has been lower than the target value. Therefore, to improve the comminution efficiency, the optimization of the design of AG mill shell liners was applied in this plant. By simulation it was found that increasing the liner lifter face angle from 7 to 30° while maintaining the original lifter height (i.e., 22.5 em) could provide an appropriate charge trajectory. Measurement of the wear profiles of shell liners indicated that the wear along the liner length was not urtiform and the highest wear occurred between 0.5 m and 1.2 m of the mill length. A new liner design was proposed by redistributing the metal from parts with a lower wear rate to the parts with a higher wear rate to arrive at a uniform wear profile along the liner length at the liner removal time. The non-uniform shell liner was constructed and installed in one of the three parallel dry AG mills. It was found that the first and second liner designs increased the mill throughput by 2.6 and 7.5%, respectively. After conversion to SAG milling on the account of liner change, 18% (from 413 to 489 t/h) increase in throughput was realized. It was predicted that the non-uniform liner designs will increase the liner life time by 10% and will reduce the scrap metal from the current value of 59% to 50%