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1
artículo
Publicado 2000
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[Y1-xCax]SrBaCu2.80(PO4)0.20Oy samples with 0.10 ≤ x ≤ 0.40 were syntherized using the solid state reaction technique. X-ray diffraction patterns show that all the compounds crystallized into a 123 tetragonal structure. The analysis of the structure with Rietveld refinement were made using a model that contains one Cu(2) in four coordination and not in five coordination as in the other 123 tetragonal structures. This fact allows that Tc increase with Ca concentration. All samples are superconductors as reported in a previous paper.
2
artículo
Publicado 2000
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(PO4)3- doped [Y0.75Ca0.25]SrBaCu3-x(PO4)xOy compounds with 0.00 ≤ x ≤ 0.30 were synthesized using the solid state reaction technique at normal pressure and temperture conditions. The X-ray diffraction patterns show that for x= 0.0 the samples crystallize into an orthorhombic phase, and for other x values the samples presented a tetragonal structure. The Rietveld method was used to refine the lattice constants. The analysis of structure with Rietveld refinement was done using a model that contains one Cu(2) in a four coordination and not in five coordination in the other 123 tetragonal structures. All samples are superconductors as reported previously [1].
3
artículo
Publicado 2011
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A structural study of the incorporation of Pr-ion into the Y-site was realized in polycrystalline samples of [Y1−xPrx]Ba2Cu3O7 through of Rietveld analysis of X-ray diffraction patterns, bond valence method and electronic density diagrams correlating its doping effects on the superconducting properties. The oxygen content was checked by means of μ-Raman spectroscopy, observing the frequency position of OO4-Ag phonon mode, and establishing a relationship among the O4-Ag mode frequency and the two copper sites, Cu(1) and Cu(2). Two regions are observed with Pr-rich and Y-rich microstructures.
4
artículo
Publicado 2023
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We report the study on the synthesis of indium-doped cobalt ludwigite (Co2InBO5). The Match program, applied to the XRD powder standard, determined that the compound consists of two phases: phase I, ludwigite Co2InBO5 and phase II, the indium oxide In2O3 impurity. The Rietveld refinement applied to the XRD powder standard determined that the percentage by weight of phase I was 98.18% and the percentage by weight of phase II was 1.82%. The atomic ratio between Co and in corresponded to Co/In=2/1, for a goodness of fit s = 1.64 and Chi2 ≅ 2.70. With these adjustment values, the chemical content of the experimental compound was adjusted to its theoretical chemical stoichiometric content. In the unit cell, the different types of atoms occupied the Wyckoff positions 2b, 2c, 4g, and 4h. Atoms of the same or different types can occupy the same Wyckoff position, but a group of them occupy equi...
5
artículo
This paper presents a static analysis of functionally graded plates (FGPs) by using a new first shear deformation theory (FSDT). This theory contains only four unknowns, with is even less than the classical FSDT. In this paper a simply supported FG square sandwich plate is subjected to a bi-sinusoidal load. The governing equations for static bending analysis are derived by employing the principle of virtual works. These equations are then solved via Navier-type, closed form solutions. The accuracy of the present theory is ascertained by comparing it with various available solutions in the literature.
6
artículo
Publicado 2022
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Purpose – Much research has been conducted on how consumption is related to human relationships. Only a scarcity of studies has examined brand and product selection, as well as the consumption activities that individuals follow when pursuing a sense of group belonging. The literature comprises a single theoretical framework describing this phenomenon, a nascent proposition on which further research remains undeveloped. This study aims to examine the transferability of that theoretical framework in a different context to that used for its elaboration and its descriptive scope on purchasing goods and engaging inn consumption activities to leverage belonging. Design/methodology/approach – A deductive qualitative case study and pattern matching analysis technique were used, followed by structural coding analysis of interview data. Findings – Findings reveal that the model is transferab...
7
artículo
Publicado 2017
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In this study, magnetic nanocomposites were developed and used as adsorbents for lead and copper from aqueous media. Structural, surface, magnetic and textural properties of functionalized maghemite nanoparticles synthesized by alkaline co-precipitation were studied. The surfaces of the iron oxide nanoparticles (Nps) were modified with different chemical agents such as fatty and amino acids, silica (SiO2), mesoporous silica (SBA-15), hydroxyapatite, multiwall carbon nanotubes (MWCNTs) and ethylenediaminetetraacetic acid (EDTA), obtaining NPs with mean particle sizes ranging from 7 to 16 nm according to Rietveld refinement and TEM images analysis. The physicochemical surface properties of the functionalized materials were studied via zeta potential (z) and Fourier transform infrared (FTIR) spectroscopy. Mossbauer spectroscopy (MS) as a function of temperature and DC magnetometry were ¨ u...
8
artículo
Publicado 2019
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Structures in chemical and petrochemical facilities are often located in areas that may be subjected to blast loading. Occupied buildings typically have non-structural components located along the interior of the exterior walls and roof such as windows, doors, wall mounted AC units, lights, furniture, storage racks, hanging equipment, and loose articles. Occupants of buildings subjected to accidental explosions may be injured from glass fragments and interior non-structural items becoming projectiles and impacting building occupants. As a pressure wave from a blast impacts the exterior of a building, the wall and roof components are rapidly accelerated inward. Equipment or contents mounted on or in contact with the exterior façade are also accelerated and may be dislodged and projected as debris. Items anchored to the ceiling structure can be thrown vertically from the initial forward d...
9
artículo
Publicado 2019
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Structures in chemical and petrochemical facilities are often located in areas that may be subjected to blast loading. Occupied buildings typically have non-structural components located along the interior of the exterior walls and roof such as windows, doors, wall mounted AC units, lights, furniture, storage racks, hanging equipment, and loose articles. Occupants of buildings subjected to accidental explosions may be injured from glass fragments and interior non-structural items becoming projectiles and impacting building occupants. As a pressure wave from a blast impacts the exterior of a building, the wall and roof components are rapidly accelerated inward. Equipment or contents mounted on or in contact with the exterior façade are also accelerated and may be dislodged and projected as debris. Items anchored to the ceiling structure can be thrown vertically from the initial forward d...
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11
artículo
Publicado 2012
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In this work we report the structural and electronic properties of the compound [Y0.8Ca0.2](Ba0.5Sr0.5)2Cu3O7-δ (YCaBaSr) which is a superconductor below the critical temperature TC = 80 K. This compound was prepared using the Sol-Gel method. The structural properties were studied by X-ray diffraction and electronic properties were studied by X-ray Photoemission Spectroscopy (XPS). The results were compared with those ones of the traditional superconductor YBa2Cu3O7-δ (YBCO). The X-ray photoemission spectra were taken at room temperature (normal state) and at 30 K (superconductor state). In the superconductor state, the X-ray photoemission spectra showed a shift in the O 1s. While the position of the Cu3p principal peaks do not change when measuring at 30 K. However, the spectra reveal the appearance of a new peak due to de hybridization of the Cu3d and O2p states. In addition, the Fou...
12
artículo
Publicado 2021
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Disordered crystalline Fe50Mn25+xSn25?x alloys, with x =-1.25, 0.0, 2.5, 5.0, 7.5 (close to the full-Heusler alloys), were arc-melted in a high purity argon atmosphere and the molten pellets were individually sealed in quartz tubes also under argon atmosphere. Subsequently, they were annealed at 1173 K for 4 days, being finally quenched in a bath with cold water. Structural and magnetic properties have systematically been studied using X-ray diffraction,57Fe, and119Sn Mössbauer spectroscopies, and magnetization measurements recorded at room temperature. Rietveld refinement of the X-ray diffraction patterns of the annealed samples with x =-1.25 and 0 has revealed the presence of two hexagonal crystallographic phases: (i) a chemically disordered solid solution identified as ??(Fe/Mn)3Sn (majority fraction) and (ii) the ??Fe5Sn3 intermetallic compound (minority fraction). For samples with ...
13
artículo
Publicado 2012
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En este trabajo se reporta las propiedades estructurales y electrónicas del compuesto [Y0.8Ca0.2](Ba0.5Sr0.5)2Cu3O7-δ (YCaBaSr) que es superconductor con temperatura crítica TC = 80 K. El compuesto fue preparado mediante el método Sol-Gel. Las propiedades estructurales y electrónicas de este compuesto se estudiaron mediante difracción de rayos X (DRX) y espectroscopia de fotoemisión de rayos X (XPS) respectivamente. Los resultados fueron comparados con los del superconductor tradicional YBa2Cu3O7- δ (YBCO). Las medidas por XPS se realizaron a temperatura ambiente (en el estado normal) y a 30 K (estado superconductor). En el estado superconductor, los espectros XPS de ambos compuestos muestran corrimiento en el pico O 1s. Mientras que, la posición de los picos principales del Cu 3p no cambian de posición al ser medidos a 30 K y 293 K. Sin embargo, se observa en el espectro la ap...
14
tesis de grado
Analysis of the characterization of the adhesion property in intermediate layers of asphalt pavement
Publicado 2025
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The present study analyzes the characterization of adhesion properties in intermediate layers of asphalt pavement, a critical factor influencing road durability and performance. The research is based on a systematic review of scientific literature, highlighting different methodologies for evaluating interlayer bonding, experimental tests, and international standards such as AASHTO, ASTM, and MTC regulations. A comparative analysis was conducted between samples obtained from the “Improvement of the Santa Maria - Santa Teresa - Hydroelectric Machu Picchu Bridge Road” project and laboratory simulations using the LOTTMAN test. The results demonstrate that the amount of tack coat significantly affects interlayer adhesion. Experimental tests confirmed that a tack coat application rate of 0.4 l/m² provides optimal indirect tensile strength (TSR) values, improving mechanical bonding between...
15
artículo
Publicado 2024
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The purpose of this paper is to provide a theoretical approach to the notion of political counter-narrative. Given the novelty of this narrative technique, its causes are first addressed: moral absolutism, affective polarization, informational chaos, uncertainty, and digital tribalism. Then, the counter-narrative is defined as a semantic structure that, regardless of temporality, seeks to destroy the symbolic capital of the adversary. Subsequently, its main features –reactivity, negativity, emotiveness, stereotyping, and permanence– are detailed, as are its functions –linking wills through opposition, drawing clear identity boundaries, being emotionally rewarding, and simplifying reality–. In closing, a review of the main findings is provided, and various lines of research are proposed, such as observing the resonance and application of this technique by citizens and the possibil...
16
artículo
Publicado 2017
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The Camaná-Mollendo Basin is an active-margin depression ~NW-SE elongated, which is located in the forearc of southern Perú and extends from the Coastal Cordillera to the Perú-Chile Trench. This basin consists of a grabens and half-graben complex, filled with deltaic and fluvial sedimentary rocks of the Oligocene-Pliocene Camaná Formation (~500 m thick). An integration of compiled onshore stratigraphic logs, reinterpreted 2D seismic offshore information, sediment provenance data, and previous zircon U-Pb geochronology on volcanic reworked ash supports a refined tectono-chronostratigraphic framework for the whole Camaná-Mollendo Basin fill. To complete this integration we needed firstly to elaborate a geological reinterpretation of seismic offshore data and highlight their most prominent features (i.e., erosive surfaces). This step allowed establishing a first correlation between ons...
17
artículo
Publicado 2025
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This study examines the effect of technostress on boreout syndrome among municipal workers in Lambayeque, Peru, addressing a significant gap in the literature regarding the relationship between technological stressors and workplace disengagement. Using a quantitative, correlational, non- experimental design, data were collected from 300 municipal employees through validated scales measuring technostress (RED-TIC) and boreout syndrome. Structural equation modeling with partial least squares (PLS-SEM) was employed to test the hypothesized relationships. Contrary to theoretical expectations, results revealed a significant negative relationship between technostress and boreout syndrome (β = −0.584; p < 0.001), with a large effect size (f² = 0.519). This paradoxical finding suggests that technological demands may serve as cognitive activators that protect against workplace boredom and dis...
18
artículo
In this article a proposal is presented for a theoretical framework that could provide the structure and coherence needed for the development of effective LMOOCs (Language MOOCs) and MALL (Mobile Assisted Language Learning) apps in a systematic way that would facilitate online second language learning. The framework is argued to be appropriate for language teaching and learning since it could be used for the elaboration of online courses such as LMOOCs and syllabi and didactic materials for MALL apps, regardless of the number of students. It has been refined during the process of designing and developing a Professional English LMOOC and the examples provided here are from that course. The framework is built upon the CEFR (The Common European Framework of Reference for Languages: Learning, Teaching, Assessment) since it offers a way to structure the knowledge and skills required in second...
19
artículo
In this article a proposal is presented for a theoretical framework that could provide the structure and coherence needed for the development of effective LMOOCs (Language MOOCs) and MALL (Mobile Assisted Language Learning) apps in a systematic way that would facilitate online second language learning. The framework is argued to be appropriate for language teaching and learning since it could be used for the elaboration of online courses such as LMOOCs and syllabi and didactic materials for MALL apps, regardless of the number of students. It has been refined during the process of designing and developing a Professional English LMOOC and the examples provided here are from that course. The framework is built upon the CEFR (The Common European Framework of Reference for Languages: Learning, Teaching, Assessment) since it offers a way to structure the knowledge and skills required in second...
20
artículo
Publicado 2025
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Flame acceleration plays an important role in determining the onset of deflagration-to-detonation transition (DDT) phenomenon that is relevant to novel pressure-gain propulsion and explosion safety research. Accordingly, this work explores the influence of the separation distance between obstacles (S) inside a 1050 mm closed duct on the acceleration of premixed flames fueled by a stoichiometric methane/air mixture at 40 kPa pressure. The studied duct geometry features a 96 mm x 96 mm square cross section and includes five obstacles along the wall with a 75% blockage ratio, each delineated by side dimensions of 96 mm x 96 mm and square holes of 48 mm x 48 mm. Experimental and direct numerical simulations (DNS) techniques are employed here to investigate the flame acceleration dynamics under different operating conditions. More specifically, high-speed video captures the dynamics of ...
