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Cruz-Silva, Rodolfo,Morelos-Gomez, Aaron,Kim, Hyung-ick,Jang, Hong-kyu,Tristan, Ferdinando,Vega-Diaz, Sofia,Rajukumar, Lakshmy P.,Elí,as, Ana Laura,Perea-Lopez, Nestor,Suhr, Jonghwan,Endo, Morin American Chemical Society 2014 ACS NANO Vol.8 No.6
<P>Graphene oxide (GO) has recently become an attractive building block for fabricating graphene-based functional materials. GO films and fibers have been prepared mainly by vacuum filtration and wet spinning. These materials exhibit relatively high Young’s moduli but low toughness and a high tendency to tear or break. Here, we report an alternative method, using bar coating and drying of water/GO dispersions, for preparing large-area GO thin films (<I>e.g.</I>, 800–1200 cm<SUP>2</SUP> or larger) with an outstanding mechanical behavior and excellent tear resistance. These dried films were subsequently scrolled to prepare GO fibers with extremely large elongation to fracture (up to 76%), high toughness (up to 17 J/m<SUP>3</SUP>), and attractive macroscopic properties, such as uniform circular cross section, smooth surface, and great knotability. This method is simple, and after thermal reduction of the GO material, it can render highly electrically conducting graphene-based fibers with values up to 416 S/cm at room temperature. In this context, GO fibers annealed at 2000 °C were also successfully used as electron field emitters operating at low turn on voltages of <I>ca.</I> 0.48 V/μm and high current densities (5.3 A/cm<SUP>2</SUP>). Robust GO fibers and large-area films with fascinating architectures and outstanding mechanical and electrical properties were prepared with bar coating followed by dry film scrolling.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-6/nn501098d/production/images/medium/nn-2014-01098d_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn501098d'>ACS Electronic Supporting Info</A></P>
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.
Gutierrez-Vargas, Gildardo,Ruiz, Alberto,Lopez-Morelos, Victor H.,Kim, Jin-Yeon,Gonzalez-Sanchez, Jorge,Medina-Flores, Ariosto Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.9
One of the consequences of the 475 ℃ embrittlement of duplex stainless steels is the reduction of the resistance to localized corrosion. Therefore, the detection of this type of embrittlement before the material exhibits significant loss in toughness, and corrosion resistance is important to ensure the structural integrity of critical components under corrosion threats. In this research, conductivity measurements are performed using the alternating current potential drop (ACPD) technique with using a portable four-point probe as a nondestructive evaluation (NDE) method for detecting the embrittlement in a 2507 (UNS S32750) super duplex stainless steel (SDSS) aged at 475 ℃ from as-received condition to 300 h. The electric conductivity results were compared against two electrochemical tests namely double loop electrochemical potentiokinetic reactivation (DL-EPR) and critical pitting temperature (CPT). Mechanical tests and the microstructure characterized using scanning electron microscopy (SEM) imaging are conducted to track the progress of embrittlement. It is shown that the electric conductivity correlates with the changes in impact energy, microhardness, and CPT corrosion tests result demonstrating the feasibility of the four-point probe as a possible field-deployable method for evaluating the 475 ℃ embrittlement of 2507 SDSS.
L. R. Jacobo,R. García‑Hernández,V. H. López‑Morelos,A. Contreras 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
The effect of acicular ferrite (AF) and bainite (B) obtained by heat treatment (HT) applied to an API X70 steel on corrosionresistance and stress corrosion cracking (SCC) susceptibility was evaluated through polarization curves and slow strain ratetests respectively, in NS4 solution and congenital water (CW). The HT was carried out at 1050 °C for 15 and 30 min followedby water quenching. Change of ferrite–perlite to AF and B was observed as result of heat treatment applied to X70steel. Effect of HT time in terms of microstructure obtained was analysed. The mechanical properties obtained by the HTare higher than X100 steel. HT-30 min improve the corrosion resistance of X70 steel exposed to both solutions, which arerelated to coarse and homogeneous microstructure of AF and B. Localized corrosion was observed in the steel exposed toboth solutions. HT-15 min improve mechanical properties and higher content of fine AF, but decreases SCC resistance. Steel with higher content of fine AF microstructure is more susceptible to SCC. SCC indexes revealed that the heat-treatedsteel could be susceptible to SCC in CW confirmed by the secondary cracks observed. The SCC mechanism was hydrogenembrittlement. Meanwhile, steel HT by 15 min exposed to NS4 solution could be susceptible to SCC. Crack growth rate washigher in steel HT by 15 min, which are related to more fine and brittle AF microstructure.
Rosales, Azucena Moreno,Molina, Miguel Corres,Moo, Jacqueline Gongora,Morelos, Pablo Romero,Bandala, Cindy Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.11
Background: In Mexico, breast cancer (BCa) is in first place regarding cancer mortality and has been established as a priority health issue. The incidence of metastasis from BCa is very high and presents as the principal mortality factor among women younger than 40 years of age. OBJECTIVE. To determine any associations between clinicopathological characteristics and metastasis in Mexican women under 40 years of age. Methods: During the 2010-2015 period, a total of 180 female BCa cases seen at the Navy General High Specialty Hospital, SEMAR, in Mexico City; we collected information on 20 patients with BCa younger than 40 years of age. Statistical analyses were conducted using the Kolmogorov-Smirnov, Students t, Fisher, Chi square, and Mantel-Haenszel tests. Results: The prevalence of women with BCa younger than the age of 40 years during the 2010-2015 period was 13.3%. We found a high frequency of obesity in of these cases (>75%); 100% of obese patients with a history of smoking presented with metastasis (p <0.05). In addition, the hormone phenotype was important; HER2-positive cases were 12 times more likely tto exhibit metastasis (p <0.05), while expression of estrogen and progesterone receptors appeared to be protective. Diabetes mellitus in combination with smoking was also a risk factor for development of metastasis (p <0.05). Conclusion: In this study, we obtained essential data regarding risk of metastasis in young breast cancer cases which could be useful for predicting disease evolution and treatment response.
Neural Transdifferentiation: MAPTau Gene Expression in Breast Cancer Cells
Lara-Padilla, E,Miliar-Garcia, A,Gomez-Lopez, M,Romero-Morelos, P,Bazan-Mendez, CI,Alfaro-Rodriguez, A,Anaya-Ruiz, M,Callender, K,Carlos, A,Bandala, C Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4
Background: In tumor cells, aberrant differentiation programs have been described. Several neuronal proteins have been found associated with morphological neuronal-glial changes in breast cancer (BCa). These neuronal proteins have been related to mechanisms that are involved in carcinogenesis; however, this regulation is not well understood. Microtubule-associated protein-tau (MAP-Tau) has been describing in BCa but not its variants. This finding could partly explain the neuronal-glial morphology of BCa cells. Our aim was to determine mRNA expression of MAP-tau variants 2, 4 and 6 in breast cancer cell lines. Materials and Methods: Cultured cell lines MCF-10A, MDA-MB-231, SKBR3 and T47D were observed under phase-contrast microscopy for neural morphology and analyzed for gene expression of MAP-Tau transcript variants 2, 4 and 6 by real-time PCR. Results: Regarding morphology like neural/glial cells, T47D line shown more cells with these features than MDA-MB-231 and SKBR. In another hand, we found much greater mRNA expression of MAP-Tau transcript variants 2, and to a lesser extent 4 and 6, in T47D cells than the other lines. In conclusion, regulation of MAP-Tau could bring about changes in cytoskeleton, cell morphology and motility; these findings cast further light on neuronal transdifferentiation in BCa.
Evaluation of thermal embrittlement in 2507 super duplex stainless steel using thermoelectric power
Gildardo Gutierrez-Vargas,Alberto Ruiz,김진연,Víctor H. Lopez-Morelos,Ricardo R. Ambriz 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7
This research investigates the feasibility of using the thermoelectric power to monitor the thermal embrittlement in 2507 super duplex stainless steel (SDSS) exposed to a temperature between 280 °C and 500 °C. It is well known that the precipitation of Cr-rich α′ phase as a result of the spinodal decomposition is the major cause of the embrittlement and the loss of corrosion resistance in this material. The specimens are thermally aged at 475 °C for different holding times. A series of mechanical testing including the tensile test, Vickers microhardness measurement, and Charpy impact test are conducted to determine the property changes with holding time due to the embrittlement. The mechanical strengths and ferrite hardness exhibit very similar trends. Scanning electron microscopy images of impact-fractured surfaces reveal a ductile to brittle transition in the fracture mode as direct evidence of the embrittlement. It is shown that the thermoelectric power is highly sensitive to the thermal embrittlement and has an excellent linear correlation with the ferrite hardness. This paper, therefore, demonstrates that the thermoelectric power is an excellent nondestructive evaluation technique for detecting and evaluating the 475 °C embrittlement of field 2507 SDSS structures.