In most open pit mines, the first step in the operation cycle of a mining unit is drilling and blasting. One of the most important results of blasting in mines is rock fragmentation. The dimensions of the crushed parts, resulting from the blast, are effective in the costs of loading, haulage, and crushing operations. Many studies have been done in relation to understanding the blasting mechanism and introducing different charging patterns. One of the most practical charging methods that is used today in production blasts in mines is placing an air column along the charging column. This method leads to a change in blast mechanism compared to continuous charging by producing secondary pressures. In this research, the ratio of the optimal length of the air column in the limestone mass has been numerically studied in terms of rock damage. For the analysis and validation of the numerical model of the single blast hole, the field studies of other researchers have been used. In the present simulation, the length of the air column is designed between 0. 3 and 0. 9 meters. The results represent that by escalating the length of the air column up to 0. 7 meters, the pressure applied to the stemming column and fly rock velocity increase with the rate of 1. 18 and 1. 3, respectively. For longer lengths, this rate increases to 1. 58 and 2. 39, respectively. It is caused by excessive reduction of the stemming length. The radius analysis of damage in the limestone mass around the blast hole demonstrates that the maximum damage is achieved for the air column with a length of 0. 7 meters (air column length ratio was 21. 9).

Length of natural gas flame with stochiometric air to fuel ratio and also with 5 percent excess air for 15 MW burners which are used in large furnaces has been characterized by empirical equations reported in the literatures. In these investigations it was shown that the axial component of radiationis neglected, since it is relatively small compared to the radial component. This model has been employed to study the influence of firing rate and also examines the preheating air on the characteristics of flame.A one-dimensional model was used to predict the axial temperature profiles of the flame. Results indicate that the temperature at the nozzle of burner is small, but increases sharply along the axes of the flame. The effect of various speaces in the flame up to 1500k was found to be negligible and usually ignored in practice. The higher the temperature of the flame the more incomplete will be the combustion in the flame and so reduces the flame temperature.

Protective steel doors are widely used in buildings due to their high resistance against the impact loads. However, its heavy weight has been always considered as a major drawback for these doors. In this paper, a new optimized stiffened impact-protective steel door incorporating sandwich panel with aluminum foam core (OSSA) is examined. This door consists of two face sheets, main and secondary stiffeners, and aluminum foam as the inner core. In order to optimize the door, at first the rigidity and weight functions of the stiffened steel door were extracted. Then an optimal door weighing 42% less than the primary door was obtained. Due to the high energy absorption capacity of the combined foam core and stiffened steel door structure, the use of aluminum foam core in the optimized steel door was proposed. By doing numerical analysis, and depending on the thickness of the face sheet of OSSA, 20 to 32% reduction in the maximum displacement was observed. The results also showed that, with 67% increase in the peak overpressure, OSSA has kept almost the same maximum displacement as that of the steel door without an aluminum foam. In other words, by using aluminum foam core in the optimized stiffened door, the door will resist 67% more impact load.

In order to study biozones of the Pabdeh Formation in the Northeast Kazerun, Murdak section was selected. In this section, Pabdeh Formation is mainly consists of marl, shale and marly limestone. The study of calcareous nannofossils led to the recognition of 70 species and 28 genera. According to the first and last occurrence of index species and assemblages fossil, the following biozones based on global standard zonations are identified: Discoaster multiradiatus Zone (NP9/ CNP11), Tribrachiatus contortus Zone (NP10/ CNE1-CNE2), Discoaster binodosus Zone (NP11/ CNE3), Tribrachiatus orthostylus Zone (NP12/ CNE4), Discoaster lodoensis Zone (NP13/ CNE5), Discoaster sunlodoensis Zone (NP14/ CNE6-CNE8), Nannotetrina fulgens Zone (NP15/ CNE9-CNE11), Discoaster tanii nodifer Zone (NP16/ CNE12-CNE15), Discoaster saipanensis Zone (NP17/ CNE15-CNE16), Chiasmolithus oamaruensis Zone (NP18/ CNE17-CNE18), Isthmolithus recurvus Zone (NP19/ CNE18-CNE19), Sphenolithus pseudoradians Zone (NP20/ CNE20), Ericsonia Subdisticha Zone (NP21/ CNE21-CNO1), Helicosphaera reticulate Zone (NP22/ CNO2), Sphenolithus predistintus Zone (NP23/ CNO3-CNO4). As a result of this study and based on the obtained biozones, the age of Pabdeh Formation in Murdak section, is Late Paleocene (Thanetian) to Oligocene (Rupelian-Chatian).

Background and Objective: Degeneration of neurons in the central nervous system occurs during aging. Transplantation of neural stem cells (NSCs) can be preventing the degeneration of neurons. In addition to neuronal replacement, with the production of neurotrophic factors, increased survival and proliferation of endogenous cells. This study was done to compare the cell proliferation, neurotrophic factors expression and features of NSCs harvested from different areas of the central nervous system in vitro.Materials and Methods: In this laboratory study NSCs have been harvested from subgranular zone (SGZ), subventricular zone (SVZ) and central canal of spinal cord from adult Wistar rats with mechanical, enzymatical digestion and subsequently was cultured in α-MEM medium supplemented with serum as monolayer or adherent conditions and passaged for 13 times. Immunocytochemistry was used to determine expression of the nestin and GFAP markers. Semi-quantitative RT–PCR was used to confirm genes expression (NGF, CNTF, NT3, NT4.5, GDNF and BDNF).Results: Morphological features of stem cells extracted from different regions of the central nervous system were similar in the culture. Doubling time NSCs in the SVZ (37.45 hr) is shorter than in the SGZ (44.04 hr) and central canal of spinal cord (57.22 hr). The culture conditions as well as monolayer neural stem cells are capable of producing neurospheres. Also, nestin and GFAP markers, expressed by NSCs. Neurotrophic gene expression pattern profiles were similar to each other in stem cells extracted from the SGZ, SVZ and central canal of spinal cord.Conclusion: Neurotrophic gene expression in stem cells extracted from different regions of the central nervous system were similar, but proliferation capacity was higher in NSCs, which have been harvested from the SVZ.

The mill shell liner type, rotation speed and the amount of its loading are the key factors influencing the charging behavior, consequently the comminution mechanism. In this paper, the milling operation of industrial ball mills using the Discrete Element Method (DEM) is investigated. First, an industrial scale ball mill with a Smooth liner type is simulated. Then, by changing liner type, i. e. Wave, Rib, Ship-lap, Lorain, Osborn, and Step liners, six other independent simulations are performed. Effects of mill shell liner type on charge shoulder, toe, impact, and head points, also on head height and impact zone length as well as on the creation of cascading, cataracting, and centrifuging motions for balls at two different mill speeds, i. e. 70% and 80% of its critical speed (NC) are evaluated. Also, in order to validate simulation results, a laboratory-scale mill is simulated. The results indicate that the charge heads are respectively about 240. 13, 283. 40, 306. 47, 278. 12, 274. 42, 274. 42, and 278. 12 cm at the simulations performed with Smooth, Wave, Rib, Ship-lap, Lorain, Osborn, and Step liners at 70% of NC. The corresponding values at 80% of NC are as follows: 256. 08, 264. 56, 313. 54, 298. 45, 313. 54, 311. 60, and 283. 40 cm. On the other hand, the impact zone lengths are respectively about 33. 14, 22. 11, 38. 63, 35. 86, 38. 63, 38. 63, and 49. 59 cm at the simulations performed with the above-mentioned liners at 70% of NC. The corresponding values for impact zone lengths at 80% of NC are as follows: 35. 86, 27. 63, 49. 59, 38. 63, 33. 14, 52. 32, and 41. 38 cm. Comparison of the simulations related to the laboratory scale mill with experimental results demonstrates a good agreement that validates the DEM simulations and the software used.

Introduction: Central vein catheterization is a standard clinical method for central venous pressure monitoring besides being used for other therapeutic purposes. The present guidelines recommend to place the catheter tip in the superior vena cava above the pericardial cephalic reflection. The aim of this study was to compare the accuracy of two different approaches in locating the tip of the CVC at the suggested vascular zone.Material and methods: This was an interventional study on 100 patients undergoing CABG operation who required a central venous cannulation. They were randomly assigned into two groups. In the first group catheter placement was applied through using the conventional 15 cm method. In the second group a Clength method was applied for measuring the depth of catheter tip insertion from the preoperative chest radiographs. For statistical analysis Chi-square test and T-test were used (SPSS v.22 software).Results: In the first group (15 cm) 100% of the patients had their catheters placed below the C-line (Carina line) and the average distance between the catheter tip and the C-line was 4.22±2.10 cm. In the second (CLength) group 52% of the catheters were below C-line with an average distance of 0.77±0.5 cm. There was a meaningful difference between the two groups in respect to the catheter location depth and zone placement. (P=0.00) Conclusion: The C-Length approach in comparison to the conventional 15 cm approach resulted in a considerable higher number of catheters above the recommended C-line, thus it can provide a more reliable and safe mode for CVC placement in the SVC.