Instituto Tecnológico de Morelia

About: Instituto Tecnológico de Morelia is a education organization based out in Morelia, Mexico. It is known for research contribution in the topics: Electric power system & AC power. The organization has 498 authors who have published 572 publications receiving 4600 citations.

A Mathematical Simulator for the EAF Steelmaking Process Using Direct Reduced Iron

Abstract: A mathematical simulator for the melting operation of direct reduced iron in electric arc furnaces (EAF) has been developed. The simulator takes into account the changes of physical properties of slag with time as well as the operating aspects of the process by using different input types of the raw materials into the furnace. Control of the bath oxidation is performed through the injection of carbon fines in the slag. Cost-optimized mass and energy balances are employed as generators of initial and boundary conditions to start the solution of a set of ordinary differential equations whose solution allows to know the dynamic changes of temperature and metal and slag chemistry with time. Simulation results indicate that the final bath oxidation level is more dependent on the process routes than on the quality of the direct reduced iron (DRI) being melted. High carbon wettability by slags and basic slags are the most suitable conditions to promote iron oxide reduction in order to maintain a low bath oxidation. Process outputs influenced by complex EAF operations using different DRI metallizations, different sequences for feeding raw materials in the furnace, injection of carbon and oxygen and different types of inputs are well predicted by the present mathematical simulator.

How conserved are the conserved 16S-rRNA regions?

Abstract: The 16S rRNA gene has been used as master key for studying prokaryotic diversity in almost every environment. Despite the claim of several researchers to have the best universal primers, the reality is that no primer has been demonstrated to be truly universal. This suggests that conserved regions of the gene may not be as conserved as expected. The aim of this study was to evaluate the conservation degree of the so-called conserved regions flanking the hypervariable regions of the 16S rRNA gene. Data contained in SILVA database (release 123) were used for the study. Primers reported as matches of each conserved region were assembled to form contigs; sequences sizing 12 nucleotides (12-mers) were extracted from these contigs and searched into the entire set of SILVA sequences. Frequency analysis shown that extreme regions, 1 and 10, registered the lowest frequencies. 12-mer frequencies revealed segments of contigs that were not as conserved as expected (≤90%). Fragments corresponding to the primer contigs 3, 4, 5b and 6a were recovered from all sequences in SILVA database. Nucleotide frequency analysis in each consensus demonstrated that only a small fraction of these so-called conserved regions is truly conserved in non-redundant sequences. It could be concluded that conserved regions of the 16S rRNA gene exhibit considerable variation that has to be considered when using this gene as biomarker.

A comparison between two different numerical formulations of welding arc simulation

Abstract: A mathematical model was developed to simulate gas tungsten arc welding in order to compare two distinct numerical formulations to represent the electromagnetic problem in welding arcs, i.e. the `potential' and the `magnetic' approaches. Both formulations, representing the same physics but mathematically and numerically different, are tested against each other and against some experimental measurements available and other numerical studies reported in the literature. The major differences between the two formulations were found in predicting the magnetic and the current density fields. In general, the magnetic approach seems to be more straightforward to implement but the potential approach shows superiority in predicting isotherms, current and heat flux densities at the anode, since they show better agreement with experimental measurements. In view of the experience developed and the analysis carried out in this paper, it is clear to the authors that employing the potential formulation results in an easier, more convenient, and numerically better-behaved approach to represent welding arcs.

Quantification of Phenolic Compounds and In Vitro Radical Scavenging Abilities with Leaf Extracts from Two Varieties of Psidium guajava L

Abstract: Guava leaf (Psidium guajava L.) extracts are used in both traditional medicine and the pharmaceutical industry. The antioxidant compounds in P. guajava leaves can have positive effects including anti-inflammatory, anti-hyperglycemic, hepatoprotective, analgesic, anti-cancer effects, as well as protecting against cardiovascular diseases. In the present study, phenolic compounds and in vitro antioxidant capacity were measured in extracts obtained with polar and non-polar solvents from leaves of two varieties of guava, Calvillo Siglo XXI and Hidrozac. The quantity of total phenolics and total flavonoids were expressed as equivalents of gallic acid and quercetin, respectively. Hydroxyl radical, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Oxygen Radical Absorbance Capacity using fluorescein (ORAC-FL) in vitro tests were used to assess the radical scavenging abilities of the extracts. The total phenolics were higher in the aqueous fraction of the variety Calvillo Siglo XXI, while in the Hidrozac variety total phenolics were higher in the acetone and chloroform fractions. Total flavonoids were higher in all fractions in the variety Calvillo Siglo XXI. Total phenolics showed a highly positive correlation for ORAC-FL, and a moderately positive correlation with hydroxyl radicals. Finally, total flavonoids showed a slightly positive correlation for ORAC-FL and hydroxyl radicals. Both varieties of guava leaf extract showed excellent antioxidant properties.