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Rafael Eduardo Hernández-Guisao,Aranda-Barradas Juan Silvestre,Badillo-Corona Agustín,García-Peña Elvia Inés,Salgado-Manjarrez Edgar 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.5
Stoichiometric analysis is a crucial step in biochemical processes because it allows us to find the proportions in which the substrates and products react. A system of algebraic equation is obtained from an elemental balance of the participating substances and determined, overdetermined or underdetermined systems can result depending on the number of substances and elements. Underdetermined systems are the most common ones as there are, generally, more substances than elemental balances. However, such systems have been poorly studied and a straightforward way to establish the solution space has not yet been reported. In this work a novel approach for finding all the possible solutions to such underdetermined systems is reported for the first time. The solutions space is expressed as a set of vectors which are here referred as extreme stoichiometries. To illustrate the general applicability and some uses of the proposed approach, three different fermentation systems are analyzed: growth of Chlamydomonas reinhardtii, a mixed culture for hydrogen production, and the growth of Saccharomyces cerevisiae. It is shown how the full stoichiometric spaces can be calculated for heterotrophy, autotrophy, mixotrophy, growth of mixed cultures in mixed substrates and how the experimental results should be contained in such spaces, what permits a consistency analysis. With the proposed method, it is now possible to estimate the maximum yields for any given microbial growth reaction and to assess the congruence of experimental data, even when the system is underdetermined.
José Aurelio Sosa,José Ramón Laines,David Salvador García,Rafael Hernández,Mark Zappi,Alejandra E. Espinosa de los Monteros 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.3
The energy growing demand and the international environmental policies contribute to the use of renewable energy sources. Among these sources, biogas has acquired great relevance due to its energetic similarity to fuels such as liquefied petroleum gas (LPG) and natural gas (NG). However, biogas needs to be upgraded by removing CO2 and trace gases to obtain biomethane (>85% CH4). This review identifies and classifies seven techniques used in biogas upgrading, reported in academic and scientific publications. A 13-year review period (2008–2021) was considered. Lineal regression was used to analyze the publications number per year. Membranes use represents the largest proportion of publications (33%), while activated carbon (AC) reaches only 22%. However, the use and application of AC obtained the best trend as a publication topic, with a maximum value of R2 = 0.7882. This review documents publish works on obtaining and applying AC in biogas enrichment processes. It includes a review of the characteristics and generation rates of various residual lignocellulosic materials used in the synthesis of AC, the synthesis processes, the characterization techniques, and the final adsorption capacities.
Heriberto Granados‑Becerra,Víctor H. López‑Morelos,Alberto Ruiz,Rafael García‑Hernández,Francisco F. Curiel‑López,Martin R. Barajas‑Alvarez 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6
The Ramberg–Osgood equation was applied to model the stress–strain behavior of heat-treated and welded specimens ofInconel 600 up to 0.2 and 0.175 mm/mm of strain, respectively. As-received and aged plates of Inconel 600 were gas metalarc welded to simulate repair of a component in operation. Dog bone shape specimens were tensile tested at a cross headspeed of 0.005 s−1 and the deformation was measured with an extensometer with a gage length of 20 mm. Microstructuralobservations were made in the optical and scanning electron microscope. Fitting the experimental data in the plastic regionof stress–strain curves to a novel three slopes Ramberg–Osgood model enabled estimation of the hardening coefficient, n. The value of n varied from 0.07 to 0.3 depending on the metallurgical condition of the specimen. A notorious increase wasobserved in the value of n for samples heat-treated beyond 25 h and in as-welded samples. The results of this work showeda very good correlation between the model and the experimental curves.