A Review on Recent Advances on Magnesia-Doloma Refractories by Nano-Technology.

Due to exhibiting an excellent chemical resistance against basic environments at high temperature, good thermal shock resistance, thermodynamic stability in the presence of carbon, and a suitable abrasion resistance, MgO-CaO refractories are widely used in argon-oxygen decarburization furnaces in the metallurgy industry and cement rotary kilns. Furthermore, MgO-CaO refractories are beneficial to removing inclusions from molten steels; thus, they have been considered to be one of the effective refractory types for processing clean steel products. Also, MgO-CaO materials have become one of the attractive steelmaking refractories because of their low cost and high ore reserves.  However, in spite of these primary advantages, the application of MgO-CaO refractories has not been popular due to its tendency to hydration when exposed to the atmosphere.  In world most of MgO-CaO bricks producers used of organic components such as tar, pitch, and peck for produce MgO-CaO refractories. But during the application of these bricks in steel and cement and industrials, they released CO and CO2 gases to air and pollute the atmosphere. For this reason, recently some researcher investigate the effect of additive nanoparticles on MgO-CaO refractories performance. They reported the used of Nano-additive have acceptable results and additive nanoparticles can replace by aforementioned environment contaminating organic compounds. In this study, we reviewed all effort that done for improving the hydration resistance of MgO-CaO refractories by application of Nano-additives with an emphasis on the beneficial the use of additives nanoparticle for reduction of environmental pollution by various industries which used of MgO-CaO refractory bricks

THE EFFECT OF NANO METER SIZE ZRO2 PARTICLES ADDITION ON THE DENSIFICATION AND HYDRATION RESISTANCE OF MAGNESITE– DOLOMITE REFRACTORIES

In this study the effect of nano meter size ZrO2 particles on the microstructure, densification and hydration resistance of magnesite –dolomite refractories was investigated. 0, 2, 4, 6 and 8 wt. % ZrO2 particles that were added to magnesite –dolomite refractories containing 35 wt. % CaO. The Hydration resistance was measured by change in the weight of specimens after 72 h at 25℃ and 95% relative humidity. The results showed with addition of nano meter size ZrO2 particles, the lattice constant of CaO increased, and the bulk density and hydration resistance of the specimens increased while apparent porosity decreased. With the addition of small amount ZrO2 the formation of CaZrO3 phase facilitated the sintering and the densification process. The mechanism of the nano meter size ZrO2 particles promoting densification and hydration resistance is decreasing the amount of free CaO in the specimens

MgO–CaO–Cr2O3 composition as a novel refractory brick: Use of Cr2O3 nanoparticles

At this study the effect of Cr2O3 nanoparticles (up to 3 wt.%) on the physical and mechanical properties of MgO–CaO refractory composition with emphasis on the hydration resistance improvement have been investigated. Specimens pressed at 90 MPa then were sintered at 1650 °C for 5 h in an electric furnace. Properties such as bulk density, apparent porosity, cold crushing strength and hydration resistance were examined. The crystalline phases and microstructure characteristics of sintered specimens were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDS), respectively. Results shown that add of the 1.5 wt.% Cr2O3 nanoparticles have the best results i.e. increased the bulk density (3.41 g/cm3), cold crushing strength (848 kg/cm2), hydration resistance (1.5%) and decreased apparent porosity (5.58%), respectively. The mechanism of specimens hydration resistance improvement are: (i) decreasing the amount of free CaO and MgO with converted to high hydration resistance phases such as CaCr2O4 and MgCr2O4 phases, (ii) promotion of the densification as well as (iii) modification of the microstructure

Modeling the Differences in Biochemical Capabilities of Pseudomonas Species by Flux Balance Analysis: How Good Are Genome-Scale Metabolic Networks at Predicting the Differences?

To date, several genome-scale metabolic networks have been reconstructed. These models cover a wide range of organisms, from bacteria to human. Such models have provided us with a framework for systematic analysis of metabolism. However, little effort has been put towards comparing biochemical capabilities of closely related species using their metabolic models. The accuracy of a model is highly dependent on the reconstruction process, as some errors may be included in the model during reconstruction. In this study, we investigated the ability of three Pseudomonas metabolic models to predict the biochemical differences, namely, iMO1086, iJP962, and iSB1139, which are related to P. aeruginosa PAO1, P. putida KT2440, and P. fluorescens SBW25, respectively. We did a comprehensive literature search for previous works containing biochemically distinguishable traits over these species. Amongst more than 1700 articles, we chose a subset of them which included experimental results suitable for in silico simulation. By simulating the conditions provided in the actual biological experiment, we performed case-dependent tests to compare the in silico results to the biological ones. We found out that iMO1086 and iJP962 were able to predict the experimental data and were much more accurate than iSB1139

Effect of eight weeks water exercise with Elaeagnus angustifolia supplementation on alkaline phosphatase and calcium serum levels in overweight and obese postmenopausal women

Background and Aims: Nowadays, osteoporosis is increasing, especially in postmenopausal women, due to hormonal changes, including some enzyme factors, such as alkaline phosphatase and blood calcium levels. Therefore, this research aimed to investigate the effect of eight weeks of water exercise with Elaeagnus angustifolia supplementation on alkaline phosphatase and calcium serum levels in overweight and obese postmenopausal women. Materials and Methods: The current apply quasi-experimental study 42 postmenopausal women living in Qazvin province, Iran, with a mean age of (52.97±5.08) years, a mean weight of (73.95±8.09) kg, and a mean height of (156±5.76) cm, were selected. Then, they were randomly divided into four groups: control (n=10), exercise + placebo (n=10), supplement (n=10), and exercise + supplement (n=12). The exercise included eight weeks of water exercise at an intensity of 60-74% of the maximum heart rate twice a week, and the supplement group received daily oral supplementation of 15 g. Blood samples were collected to measure the serum level of alkaline phosphatase with an ELISA kit and calcium with spectrophotometry method in two stages before and 24 h after the last session exercise. To analyze the differences between groups and within groups, the ANOVA test and paired t-test were used, respectively. The significance level was considered at α=0.05. Results:  The results of the study showed a significant difference only in serum calcium levels among exercise+placebo (P=0.013), exercise+supplement (P<0.001), and supplement (P<0.001) groups. No significant difference was observed in the other parameres between different groups. Conclusion: Consumption of supplementation of Elaeagnus angustifolia with water exercise could not affect alkaline phosphatase, and body composition in overweight and obese postmenopausal women