Structural and Magnetic Properties of RMO3 (R = Pr,Nd and M = Fe,Co) Perovskites

Journal of Superconductivity and Novel Magnetism - In this work, the RMO3 (R?=?Pr, Nd and M?=?Fe, Co) perovskites had been synthesized by hydrothermal method. The structural...     

Design and implementation of an information system for performance assessment of management and organization in a gas refinary

Abstract

The objective of this study is to present an information system for assessment of management and organization in a gas refinery. To achieve the objective of this study, Balanced Score Card (BSC) methodology was utilized to categorize management and organization indicators into four categories. The data related to a five year period was then collected to provide a benchmark for the refinery. Furthermore, the data from 19 developed and developing countries were collected for the purpose of benchmarking. A t‐test was then introduced to benchmark the refinery's management and organization indicators. Moreover, Data Envelopment Analysis (DEA) was used to analyze and further assess the violated indicators. Finally, an integrated information system was designed in .Net environment by C#. It was introduced to facilitate the assessment of management and organization indicators. This is the first study that introduces an information system for performance assessment of management and organization in a gas refinery by integration of BSC, DEA and t‐test.     

A Review on the Role of Non-Coding RNAs in the Pathogenesis of Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune condition related to autoantibodies against certain proteins in the postsynaptic membranes in the neuromuscular junction. This disorder has a multifactorial inheritance. The connection between environmental and genetic factors can be established by epigenetic factors, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). XLOC_003810, SNHG16, IFNG-AS1, and MALAT-1 are among the lncRNAs with a possible role in the pathoetiology of MG. Moreover, miR-150-5p, miR-155, miR-146a-5p, miR-20b, miR-21-5p, miR-126, let-7a-5p, and let-7f-5p are among miRNAs whose roles in the pathogenesis of MG has been assessed. In the current review, we summarize the impact of miRNAs and lncRNAs in the development or progression of MG.     

Influence of Co substitution on magnetoelastic properties of Er2Fe14−xCoxB (x = 1, 3 and 5) intermetallic compounds

The magnetostriction and thermal expansion of Er₂Fe_14−xCo_xB (x = 1, 3 and 5) intermetallic compounds were measured, using the strain gauge method in the temperature range 75–450 K under applied magnetic fields up to 1.5 T. For all samples the longitudinal magnetostriction (λ_l) undergoes an anomaly around the spin reorientation temperature (T_SR). It is also observed that λ_l decreases with increasing the Co content. All compounds show saturation type behaviour in their anisotropic magnetostriction curves at different temperatures and applied fields. The saturation behaviour of the compound with x = 3 occurs at higher temperatures than with x = 1 and 5. The volume magnetostriction strongly increases below μ₀H = 0.3 T, then monotonically rises with applied field up to the spin reorientation temperature. An invar type behaviour is observed above 200 K in the compound with x = 1. The results are discussed based on the temperature dependence of magnetocrystalline anisotropy of compounds below and above their T_SR.     

Evaluating recyclability of fly ash reinforced polyvinyl chloride foams

Using fly ash as a reinforcing filler can be very cost effective; however, the recycling of postconsumer products containing fly ash is of a considerable concern. In this study, the recycling of processed polyvinyl chloride (PVC) foam reinforced with fly ash was investigated by evaluating the effect of regrind content (up to 40 wt%) and fly ash content (up to 20 wt%) on the physical, mechanical, microstructural, and processing properties of the composites. Experimental results show an increase in the foam density with increasing regrind and fly ash contents. The melt viscosity increased with increasing the regrind concentration; however, it dropped with increasing the fly ash content. The tensile strength increased with increasing the regrind content, indicating a good degree of gelation in the composites. Meanwhile, the charpy impact strength of the composites decreased due to the high rigidity of fly ash particles. Dynamic mechanical analysis show that the storage modulus improved with both the addition and increasing the amount of regrind, which confirmed good stress transformation between the polymer foam matrix and the fly ash particles. The polymer matrix morphology, as was determined by scanning electron microscopy (SEM), confirmed uniform foam structure even with the addition of 40 wt% regrind in the virgin PVC. J. VINYL ADDIT. TECHNOL., 24:154–161, 2018. © 2016 Society of Plastics Engineers     

Synthesis and characterization of highly crystalline Na‐X zeolite from class F fly ash

The aim of this research is to illustrate the feasibility of transforming a byproduct of coal combustion process (fly ash) into a highly crystalline zeolite with enhanced ion exchange capacity and molecular sieving ability that can be used in various phase separation applications. The main crystalline phases present were: α‐quartz, Mullite, Hematite, Magnetite and Lime. The hydrothermal synthesis process resulted in the formation of a Na‐A in low alkalinity, and Na‐X (Na₈₈Al₈₈Si₁₀₄O₃₈₄ (H₂O)_172.1) in higher alkalinity – classified as FAU (Faujasite). Physisorption analysis using BET method revealed the presence of micropores. Cation exchange capacity increased, as high as 374 meq/g, by increasing the crystallization time. Highly ordered pore structure, enhanced specific surface area and the presence of a negative charge in the framework of Na‐X zeolite (FAU) make it a strong adsorbent and an effective molecular sieve with high shape/size selectivity for various applications, including petroleum refinery catalytic cracking units.     

The effect of particle size of fly ash (FA) on the interfacial interaction and performance of PVC/FA composites

In this study, the effect of particle size of fly ash (FA) on the interfacial interaction between the filler particles and the polymer matrix is investigated. Structural and physical characterization of FA with different particle sizes show that its chemical composition is highly dependent on the particle size. The mechanical, dynamic‐mechanical, structural, and microstructural properties of the composites are evaluated. Interfacial interaction between FA particles and the polymer matrix is assessed experimentally using a nanoindenter and numerically using two different models developed by Pukanszky and Kubat. The composites reinforced with smaller particles exhibit better mechanical, viscoelastic, and microstructural properties. Structural and interfacial studies show that, although the characterized amount of silicon oxide in the small particles is lower than the large particles, the concentration of –OH group in SiO₂ is particle‐size and surface‐area dependent. Therefore, smaller particle inclusions result in better interfacial interaction and improved properties. This observation is consistent with the numerically estimated interfacial interaction. J. VINYL ADDIT. TECHNOL., 25:134–143, 2019. © 2018 Society of Plastics Engineers     

Design and implementation of a fuzzy expert system for performance assessment of an integrated health, safety, environment (HSE) and ergonomics system: The case of a gas refinery

The objective of this study is to design a fuzzy expert system for performance assessment of health, safety, environment (HSE) and ergonomics system factors in a gas refinery. This will lead to a robust control system for continuous assessment and improvement of HSE and ergonomics performance. The importance of this study stems from the current lack of formal integrated methodologies for interpreting and evaluating performance data for HSE and ergonomics. Three important reasons to use fuzzy expert systems are (1) reduction of human error, (2) creation of expert knowledge and (3) interpretation of large amount of vague data. To achieve the objective of this study, standard indicators and technical tolerances for assessment of HSE and ergonomics factors are identified. Then, data is collected for all indicators and consequently, for each indicator four conditions are defined as “acceptance”, “low deviation”, “mid deviation” and “high deviation”. A membership function is defined for each fuzzy condition (set) because an indicator cannot be allocated to just one of the above conditions. The expert system uses fuzzy rules, which are structured with Data Engine. Previous studies have introduced HSE expert system whereas this study introduces an integrated HSE and ergonomics expert system through fuzzy logic.     

Effect of E-glass Fibers and Phlogopite Mica on the Mechanical Properties and Dimensional Stability of Rigid PVC Foams

In this work, short E-glass fibers and mica were used to enhance the dimensional stability and mechanical properties of extruded rigid polyvinyl chloride foams. Experimental results show that the dimensional stability increased by 50%, and heat resistance of the polyvinyl chloride foam improved as the amount of reinforcing solids increased in the composites. The storage modulus, tensile, and flexural strengths of the composites improved by 220, 82, and 46%, respectively. Scanning electron microscope micrographs show good interaction between glass fibers and foam cells and a good dispersion and orientation of the mica flakes along the cell walls of the polyvinyl chloride foam.     

Structural,magnetic, and electrical properties of RFeO3 (R = Dy,Ho, Yb & Lu) compounds

Journal of Materials Science: Materials in Electronics - In this research, the nanosized rare-earth orthoferrites (RFeO3) with R?=?Dy, Ho, Yb & Lu were synthesized by...