Effect of mechanical alloying on the microstructural evolution of a ferritic ODS steel with (Y-Ti-Al-Zr) addition processed by Spark Plasma Sintering (SPS)

Macia, E.,Garcia-Junceda, A.,Serrano, M.,Hong, S.J.,Campos, M. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8

The high-energy milling is one of the most extended techniques to produce Oxide dispersion strengthened (ODS) powder steels for nuclear applications. The consequences of the high energy mill process on the final powders can be measured by means of deformation level, size, morphology and alloying degree. In this work, an ODS ferritic steel, Fe-14Cr-5Al-3W-0.4Ti-0.25Y₂O₃-0.6Zr, was fabricated using two different mechanical alloying (MA) conditions (M_std and M_act) and subsequently consolidated by Spark Plasma Sintering (SPS). Milling conditions were set to evidence the effectivity of milling by changing the revolutions per minute (rpm) and dwell milling time. Differences on the particle size distribution as well as on the stored plastic deformation were observed, determining the consolidation ability of the material and the achieved microstructure. Since recrystallization depends on the plastic deformation degree, the composition of each particle and the promoted oxide dispersion, a dual grain size distribution was attained after SPS consolidation. M_act showed the highest areas of ultrafine regions when the material is consolidated at 1100 ℃. Microhardness and small punch tests were used to evaluate the material under room temperature and up to 500 ℃. The produced materials have attained remarkable mechanical properties under high temperature conditions.

Slip-resistant bolted connections under freeze-thaw cycles and low temperature

A. Fuente-García,M.A. Serrano-López,C. López-Colina,F. López-Gayarre 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.48 No.3

There are many examples of steel structures subjected to severe environmental conditions with bolted connections directly exposed to extreme climatic agents such as freeze-thaw cycles or low temperatures. Some examples are: steel bridges, mining transfer towers, wind towers... These service conditions neither are included in Eurocode 3 or EN1090-2, nor there are references in other international standards. In this experimental research, 46 specimens of non-slip joints with HV M20 bolts and four different types of contact surfaces have been studied. Half of the specimens were subjected to fourteen twelve-hours freezethaw cycles, with periodic immersion in water and temperature oscillation. Subsequently, half of the connections were subjected to a slip test under monotonic load at temperature of -20 ± 0.5 ºC and the other half at room temperature. The results were compared with others equal joints not subjected to freeze-thaw cycles and kept at room temperature for the same time. This finally resulted in 4 sets of joints by combining the freeze-thaw degradation or not with the low-temperature conditions or not in the slip testing. Therefore, a total of 16 different conditions were studied by also considering 4 different contact surfaces between the joined plates in each set. The results obtained show influence of environmental conditions on the slip resistant capacity of these joints.

Proteolytic System of Streptococcus thermophilus

( G. M. Rodriguez-serrano ),( M. Garcia-garibay ),( A. E. Cruz-guerrero ),( L. Gomez-ruiz ),( A. Ayala-nino ),( A. Castaneda-ovando ),( L. G. Gonzalez-olivares ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.10

The growth of lactic acid bacteria (LAB) generates a high number of metabolites related to aromas and flavors in fermented dairy foods. These microbial proteases are involved in protein hydrolysis that produces necessary peptides for their growth and releases different molecules of interest, like bioactive peptides, during their activity. Each genus in particular has its own proteolytic system to hydrolyze the necessary proteins to meet its requirements. This review aims to highlight the differences between the proteolytic systems of Streptococcus thermophilus and other lactic acid bacteria (Lactococcus and Lactobacillus) since they are microorganisms that are frequently used in combination with other LAB in the elaboration of fermented dairy products. Based on genetic studies and in vitro and in vivo tests, the proteolytic system of Streptococcus thermophilus has been divided into three parts: 1) a serine proteinase linked to the cellular wall that is activated in the absence of glutamine and methionine; 2) the transport of peptides and oligopeptides, which are integrated in both the Dpp system and the Ami system, respectively; according to this, it is worth mentioning that the Ami system is able to transport peptides with up to 23 amino acids while the Opp system of Lactococcus or Lactobacillus transports chains with less than 13 amino acids; and finally, 3) peptide hydrolysis by intracellular peptidases, including a group of three exclusive of S. thermophilus capable of releasing either aromatic amino acids or peptides with aromatic amino acids.

Antiproliferative and antibacterial activity of extracts of Ganoderma strains grown in vitro

Leonardo Serrano-Marquez,Angel Trigos,Alan Couttolenc,Jose M. Padron,Alla V. Shnyreva,Guillermo Mendoza 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.5

In this bioprospecting study the biologicalactivities of extracts of the in vitro culture of GanodermaMexican strains were evaluated. The extracts were testedby the Sulforhodamine B staining method for antiproliferativeactivity and the plate microdilution method forantibacterial activity. Extracts that proved bioactive inthese two activities, the antioxidant activity (Galvinoxyl,ABTS, and DPPH) and total phenolic contents (Folin-Ciocalteu) were additionally determined, as well as acutetoxicity (Artemia franciscana). In the antiproliferativeactivity Ganoderma curtisii strain (GH-16-015) obtained aremarkable value of GI50 B 50 lg/mL against tumorlines: A549, HBL-100, HeLa, and T-47D. G. curtisiistrains (GH-16-012 and GH-16-015) showed MIC values= 500 lg/mL against Staphylococcus aureus. G. curtisiistrain (GH-16-012) almost reduced by 50% theradical Galvinoxyl. Finally, G. curtisii strain (GH-16-023)presented the lowest level of toxicity with a LC50 of490.881 lg/mL against A. franciscana. These resultssupport the potential medicinal effects of Mexican strainsof G. curtisii.

Down Syndrome Developmental Brain Transcriptome Reveals Defective Oligodendrocyte Differentiation and Myelination

Olmos-Serrano, J.,Kang, H.,Tyler, William A.,Silbereis, John C.,Cheng, F.,Zhu, Y.,Pletikos, M.,Jankovic-Rapan, L.,Cramer, Nathan P.,Galdzicki, Z.,Goodliffe, J.,Peters, A.,Sethares, C.,Delalle, I.,Gold Cell Press 2016 Neuron Vol.89 No.6

Trisomy 21, or Down syndrome (DS), is the most common genetic cause of developmental delay and intellectual disability. To gain insight into the underlying molecular and cellular pathogenesis, we conducted a multi-region transcriptome analysis of DS and euploid control brains spanning from mid-fetal development to adulthood. We found genome-wide alterations in the expression of a large number of genes, many of which exhibited temporal and spatial specificity and were associated with distinct biological processes. In particular, we uncovered co-dysregulation of genes associated with oligodendrocyte differentiation and myelination that were validated via cross-species comparison to Ts65Dn trisomy mice. Furthermore, we show that hypomyelination present in Ts65Dn mice is in part due to cell-autonomous effects of trisomy on oligodendrocyte differentiation and results in slower neocortical action potential transmission. Together, these results identify defects in white matter development and function in DS, and they provide a transcriptional framework for further investigating DS neuropathogenesis.

Effect of Ag doping on the crystallization and phase transition of TiO2 nanoparticles

J. García-Serrano,E. Gómez-Hernández,M. Ocampo-Fernández,U. Pal 한국물리학회 2009 Current Applied Physics Vol.9 No.5

TiO2 nanoparticles doped with different Ag contents were prepared by a modified sol–gel method, using titanium tetraisopropoxide and silver nitrate as precursors and 2-propanol as solvent. Silver was incorporated into the TiO2 matrix via decomposition of AgNO3 during thermal treatment in different atmospheres. Effects of Ag doping on the crystallization and phase transition of the TiO2 nanoparticles were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Raman spectroscopy techniques. While air annealing incorporates silver into TiO2 matrix in silver oxide form, annealing in nitrogen incorporates metallic silver into TiO2. Formation of silver oxide increases the thermal stability of the TiO2 particles. Silver oxide affects the crystallization process of TiO2 particles and the temperature of transition form anatase to rutile. On the other hand, presence of metallic silver in the samples annealed in nitrogen atmosphere decreases the temperature of phase transition of TiO2 nanoparticles.

ANALYSIS OF THE CAPABILITIES OF A TWO-STAGE TURBOCHARGING SYSTEM TO FULFIL THE US2007 ANTI-POLLUTION DIRECTIVE FOR HEAVY DUTY DIESEL ENGINES

J. R. SERRANO,F. J. ARNAU,V. DOLZ,A. TISEIRA,M. LEJEUNE,N. AUFFRET 한국자동차공학회 2008 International journal of automotive technology Vol.9 No.3

This article presents a two-stage turbocharged heavy-duty diesel (HDD) engine designed to fulfil the US2007 anti-pollution directive. This directive imposes very restrictive limits on the NOx and particle emissions of HDD engines. In this work, the possibility of combining particle traps in the exhaust line to reduce soot emissions with very high EGR rates to reduce NOx emissions is considered. This new generation engine implements two-stage turbocharging in order to improve the bsfc when the engine is working on steady conditions as well as to optimize the engine transient response. After carrying out the tests, the results were analyzed and the engine settings were adjusted to maximise its behaviour and minimise pollutant emissions. NOx and soot emission peaks were also analyzed at engine transient conditions in order to keep them under certain levels, and thus maintain the overall pollutant emissions to a level that is as low as possible. In summary, a double-stage turbocharging configuration can greatly improve engine driveability (between 23% and 36% depending on engine speed), while reducing NOx emissions during transient evolution without increasing opacity peaks beyond the stated limits.

Bioactivity of Peptides Released During Lactic Fermentation of Amaranth Proteins with Potential Cardiovascular Protective Effect: An In Vitro Study

Alexis Ayala-Nino,Gabriela M. Rodrı´guez-Serrano,Ruben Jime´nez-Alvarado,Mirandeli Bautista-Avila,Jose´ A. Sa´nchez-Franco,Luis G. Gonza´lez-Olivares,Alberto Cepeda-Saez 한국식품영양과학회 2019 Journal of medicinal food Vol.22 No.10

Fermentation has shown to be an effective technique in bioactive peptides release. That is why in this study antihypertensive, antithrombotic, and antioxidant activity was evaluated during amaranth proteins fermentation with Lactobacillus casei Shirota and Streptococcus thermophilus 54102 in mono and combined culture. During fermentation an increase of free amine groups was observed, and no statistical differences among monocultures were shown, getting higher concentration in combined culture. This was related to antihypertensive and antioxidant activities, where the highest values were also found in the combined process (45% of angiotensin-converting enzyme inhibition, and 168 μmol Trolox equivalents per liter [TE/L] for 2,2-diphenyl-1-picrylhydrazyl, 268 μmol TE/L for 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid, and 381 μmol Fe2E/L for ferric reducing ability of plasma). On the contrary, antithrombotic activity was not related to free amine groups during fermentation, having the highest bioactivity in different moments in each experiment. L. casei Shirota and S. thermophilus 54102 are strains that are able to release bioactive peptides from amaranth protein, although amaranth is not a common matrix for the development of lactic acid bacteria. In addition, in this study it was observed for the first time that lactic acid strains are able to release bioactive peptides from amaranth protein. In addition, this methodology could be part for the development of fermented beverages, different from fermented milk, to diversify matrix to obtain a novel functional food.

Enhancement of FeCrAl-ODS steels through optimised SPS parameters and addition of novel nano-oxide formers

Meza A.,Macía E.,Serrano M.,Merten C.,Gaitzsch U.,Weißgärber T.,Campos M. 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.7

A novel approach to incorporating oxide formers into ferritic ODS production has been developed using the coprecipitation technique. This method enables the tailored design of complex nano-oxides, integrated during Mechanical Alloying (MA) and precipitated during Spark Plasma Sintering (SPS) consolidation. Findings illustrate that co-precipitation effectively produces nano-powders with customised compositions, enriching Y, Ti, and Zr in the ferritic grade to condition subsequent oxide precipitation. While the addition of Y–Ti–Zr–O nano-oxides did not prevent the formation of Y–Al–O and Al-containing nano-oxides, these were refined thanks to the presence of well-dispersed Zr. Additionally, the Spark Plasma Sintering (SPS) parameters were optimised to tailor the bimodal grain size distribution of the ODS steels, aiming for favourable strength-to-ductility ratios. Comprehensive microstructural analyses were performed using SEM, EDS, EBSD, and TEM techniques, alongside mechanical assessments involving microtensile tests conducted at room temperature and small punch tests carried out at room temperature, 300 ◦C, and 500 ◦C. The outcomes yielded promising findings, showcasing similar or better performance with conventionally manufactured ODS steels. This reinforces the effectiveness and success of this innovative approach.

An investigation of the role the donor moiety plays in modulating the efficiency of 'donor-π-acceptor-π-acceptor' organic DSSCs

Park, K.W.,Serrano, L.A.,Ahn, S.,Baek, M.H.,Wiles, A.A.,Cooke, G.,Hong, J. Pergamon Press 2017 Tetrahedron Vol.73 No.8

Three 'D-π-A-π-A' based dyes have been synthesized featuring MeO-, MeS- and Me<SUB>2</SUB>N- as donor residues and benzothiadiazole and cyanoacrylic acid residues as acceptor units. UV-vis spectroscopy, solution electrochemistry and DFT modelling indicated that the Me<SUB>2</SUB>N- residue has the most significant effect on optical and redox properties of a photosensitizer. DSSCs with the Me<SUB>2</SUB>N- functionalized dye gave the highest power conversion efficiency of the series (η = 5.61%), presumably due to the better donor ability of this unit, which promotes more effective intramolecular charge transfer (ICT) characteristics.