Co-Reinforcing Al/SiC Composites with MgAl_2O_4 Formed In Situ during the Processing by Non-Assisted Infiltration

M. I. Pech-Canul,M. Rodríguez-Reyes3,M. A. Pech-Canul,J. C. Rendón-Angeles 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.6

In this work, SiC_P and SiC_P/SiO_2 porous preforms were infiltrated without assistance in Ar→N_2 atmosphere with the alloy Al-10.3 Mg-12.04 Si (wt.%) at 1050 and 1100 °C, for 20, 40 and 60 min. It was found that a decrease in residual porosity and an increase in elastic modulus by about 22 % with respect to composites produced without SiO_2 additions to the preforms are associated with the formation of magnesium aluminate spinel (MgAl_2O_4). A concurrent increase of the matrix hardness is ascribed to a strengthening mechanism by MgAl_2O_4 formation, similar to the strengthening observed with Mg_2Si in aluminum alloys. Therefore, the spinel can be considered as a co-reinforcement of SiC_p in the aluminum matrix composites. Reactions for spinel formation and possible mechanisms for hardness enhancement are outlined.

The Factors Affecting University Teachers’ Perceptions of the EFL Industry

Cyril Reyes(Cyril Reyes ),Jee Eun Lee(Jee Eun Lee) 한국영어교과교육학회 2023 영어교과교육 Vol.22 No.2

Design and Components of Stormwater Treatment Wetlands: A Synthesis from Scientific Literature

Nash Jett Reyes(Reyes Nash Jett),Minsu Jeon(전민수),Heidi Guerra(하이디),Leehyung Kim(김이형) 대한환경공학회 2022 대한환경공학회 학술발표논문집 Vol.2022 No.11

Protective Effects against Brucella abortus 544 Infection in a Murine Macrophage Cell Line and in a Mouse Model via Treatment with Sirtuin 1 Activators Resveratrol, Piceatannol and Ginsenoside Rg3

Reyes Alisha Wehdnesday Bernardo,Kim Heejin,Huy Tran Xuan Ngoc,Nguyen Trang Thi,Min Wongi,Lee Hu Jang,Hur Jin,Lee John Hwa,Kim Suk 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.4

Brucellosis is a contagious zoonotic disease that infects millions of people annually with hundreds of millions more being exposed. It is caused by Brucella, a highly infectious bacterial species capable of infecting humans with an estimated dose of 10-100 organisms. Sirtuin 1 (SIRT1) has been reported to contribute to prevention of viral diseases as well as a chronic infection caused by Mycobacterium bovis. Here, we investigated the role of SIRT1 in the establishment of Brucella abortus infection in both in vitro and in vivo systems using the reported SIRT1 activators resveratrol (RES), piceatannol (PIC), and ginsenoside Rg3 (Rg3). In RAW264.7 cells, SIRT1 activators did not alter the adherence of Brucella or Salmonella Typhimurium. However, reduced uptake of Brucella was observed in cells treated with PIC and Rg3, and survival of Brucella within the cells was only observed to decrease in cells that were treated with Rg3, while PIC treatment reduced the intracellular survival of Salmonella. SIRT1 treatment in mice via oral route resulted in augmented Brucella resistance for PIC and Rg3, but not RES. PIC treatment favors Th2 immune response despite reduced serum proinflammatory cytokine production, while Rg3-treated mice displayed high IL-12 and IFN-γ serum production. Overall, our findings encourage further investigation into the complete mechanisms of action of the different SIRT1 activators used as well as their potential benefit as an effective alternative approach against intracellular and extracellular pathogens.

Dissipation of energy in steel frames with PR connections

Reyes-Salazar, Alfredo,Haldar, Achintya Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.9 No.3

The major sources of energy dissipation in steel frames with partially restrained (PR) connections are evaluated. Available experimental results are used to verify the mathematical model used in this study. The verified model is then used to quantify the energy dissipation in PR connections due to hysteretic behavior, due to viscous damping and at plastic hinges if they are formed. Observations are made for two load conditions: a sinusoidal load applied at the top of the frame, and a sinusoidal ground acceleration applied at the base of the frame representing a seismic loading condition. This analytical study confirms the general behavior, observed during experimental investigations, that PR connections reduce the overall stiffness of frames, but add a major source of energy dissipation. As the connections become stiffer, the contribution of PR connections in dissipating energy becomes less significant. A connection with a T ratio (representing its stiffness) of at least 0.9 should not be considered as fully restrained as is commonly assumed, since the energy dissipation characteristics are different. The flexibility of PR connections alters the fundamental frequency of the frame. Depending on the situation, it may bring the frame closer to or further from the resonance condition. If the frame approaches the resonance condition, the effect of damping is expected to be very important. However, if the frame moves away from the resonance condition, the energy dissipation at the PR connections is expected to be significant with an increase in the deformation of the frame, particularly for low damping values. For low damping values, the dissipation of energy at plastic hinges is comparable to that due to viscous damping, and increases as the frame approaches failure. For the range of parameters considered in this study, the energy dissipations at the PR connections and at the plastic hinges are of the same order of magnitude. The study quantitatively confirms the general observations made in experimental investigations for steel frames with PR connections; however, proper consideration of the stiffness of PR connections and other dynamic properties is essential in predicting the dynamic behavior.

The host immune enhancing agent Korean red ginseng oil successfully attenuates <i>Brucella abortus</i> infection in a murine model

Reyes, Alisha Wehdnesday Bernardo,Hop, Huynh Tan,Arayan, Lauren Togonon,Huy, Tran Xuan Ngoc,Park, Soo Jong,Kim, Kwang Dong,Min, WonGi,Lee, Hu Jang,Rhee, Man Hee,Kwak, Yi-Seong,Kim, Suk Elsevier Ireland Ltd 2017 Journal of Ethnopharmacology Vol.198 No.-

<P><B>Abstract</B></P> <P><B>Ethnopharmacological relevance</B></P> <P> <I>Panax ginseng</I> Meyer (Araliaceae), is one of the most valuable traditional Chinese medicines and is used for the treatment of various human diseases. In this study, we elucidated the protective mechanism of the essential oil from Korean red ginseng (RGO) against <I>Brucella</I> infection.</P> <P><B>Materials and methods</B></P> <P>The effects of RGO on <I>Brucella abortus</I> viability, NO production, uptake and intracellular growth in macrophages were investigated. Mice were intraperitoneally infected with <I>B. abortus</I> and orally treated with RGO for 14 days. The weights and bacterial numbers from each spleen were monitored, and the sera were evaluated for cytokine production.</P> <P><B>Results</B></P> <P> <I>B. abortus</I> viability was not affected, whereas NO production, internalization and intracellular replication were inhibited in RGO-treated macrophages. Bacterial adherence, F-actin polymerization and MAPK signaling protein phosphorylation (ERK1/2, JNK and p38α) were reduced and the co-localization of <I>B. abortus-</I>containing phagosomes with LAMP-1 was augmented in RGO-treated cells compared to untreated cells. RGO displayed protective effects against cell damage by inhibiting nitrite production during <I>B. abortus</I> infection in macrophages. Moreover, the spleen weight and bacterial burden were lower in the RGO-treated group than in the control group. The uninfected RGO-treated mice displayed increased TNF-α and IFN-γ production, whereas the <I>B. abortus-</I>infected RGO-treated mice showed reduced IL-10 production compared to the control.</P> <P><B>Conclusion</B></P> <P>RGO exhibits protective effects against <I>B. abortus</I> infection <I>in vitro</I> and <I>in vivo,</I> which emphasize the beneficial effects of RGO in the prevention and treatment of brucellosis.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of gallic acid on signaling kinases in murine macrophages and immune modulation against <i>Brucella abortus</i> 544 infection in mice

Reyes, Alisha Wehdnesday Bernardo,Arayan, Lauren Togonon,Hop, Huynh Tan,Ngoc Huy, Tran Xuan,Vu, Son Hai,Min, WonGi,Lee, Hu Jang,Kim, Suk Elsevier 2018 Microbial pathogenesis Vol.119 No.-

<P><B>Abstract</B></P> <P>In this study, we investigated the effects of gallic acid (GA) in intracellular signaling within murine macrophages and its contribution to host immunity during <I>Brucella</I> infection<I>. In vitro</I> analysis revealed that GA treatment decreased F-actin content and suppressed p38α phosphorylation level. <I>In vivo</I> analysis showed that GA treatment reduced inflammation and proliferation of <I>Brucella</I> in spleens of mice in comparison to PBS treatment yielding a significant protection unit. For the analysis of immune response, the uninfected GA-treated mice showed increased production of IFN-γ and MCP-1, and the <I>Brucella-</I>infected GA-treated mice showed elevated levels of IL-12p70, TNF, IFN-γ, MCP-1, IL-10 and IL-6 in comparison to negative and positive control groups, respectively. These findings demonstrate the therapeutic effects of GA against <I>Brucella</I> infection through interference on intracellular signaling pathway, induction of cytokine production and protection from bacterial proliferation in spleens of mice.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Gallic acid (GA) decreased F-actin content and p38α phosphorylation level in RAW 264.7 cells. </LI> <LI> GA reduced inflammation and proliferation of <I>Brucella</I> in the spleens of mice. </LI> <LI> GA-treated mice showed increased production of IFN-γ and MCP-1. </LI> <LI> <I>Brucella</I>-infected GA-treated mice showed elevated levels of IL-12p70, TNF, IFN-γ, MCP-1, IL-10 and IL-6. </LI> <LI> GA treatment revealed potential therapeutic effects against <I>Brucella</I> infection in animals. </LI> </UL> </P>

Ductility and ductility reduction factor for MDOF systems

Reyes-Salazar, Alfredo Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.13 No.4

Ductility capacity is comprehensively studied for steel moment-resisting frames. Local, story and global ductility are being considered. An appropriate measure of global ductility is suggested. A time domain nonlinear seismic response algorithm is used to evaluate several definitions of ductility. It is observed that for one-story structures, resembling a single degree of freedom (SDOF) system, all definitions of global ductility seem to give reasonable values. However, for complex structures it may give unreasonable values. It indicates that using SDOF systems to estimate the ductility capacity may be a very crude approximation. For multi degree of freedom (MDOF) systems some definitions may not be appropriate, even though they are used in the profession. Results also indicate that the structural global ductility of 4, commonly used for moment-resisting steel frames, cannot be justified based on this study. The ductility of MDOF structural systems and the corresponding equivalent SDOF systems is studied. The global ductility values are very different for the two representations. The ductility reduction factor $F_{\mu}$ is also estimated. For a given frame, the values of the $F_{\mu}$ parameter significantly vary from one earthquake to another, even though the maximum deformation in terms of the interstory displacement is roughly the same for all earthquakes. This is because the $F_{\mu}$ values depend on the amount of dissipated energy, which in turn depends on the plastic mechanism, formed in the frames as well as on the loading, unloading and reloading process at plastic hinges. Based on the results of this study, the Newmark and Hall procedure to relate the ductility reduction factor and the ductility parameter cannot be justified. The reason for this is that SDOF systems were used to model real frames in these studies. Higher mode effects were neglected and energy dissipation was not explicitly considered. In addition, it is not possible to observe the formation of a collapse mechanism in the equivalent SDOF systems. Therefore, the ductility parameter and the force reduction factor should be estimated by using the MDOF representation.

The <i>in vitro</i> and <i>in vivo</i> protective effects of tannin derivatives against <i>Salmonella enterica</i> serovar Typhimurium infection

Reyes, Alisha Wehdnesday Bernardo,Hong, Tae Gyu,Hop, Huynh Tan,Arayan, Lauren Togonon,Huy, Tran Xuan Ngoc,Min, Wongi,Lee, Hu Jang,Lee, Kang Seok,Kim, Suk Elsevier 2017 Microbial pathogenesis Vol.109 No.-

<P><B>Abstract</B></P> <P>In this study, we investigated the protective effects of tannin-derived components, gallic acid (GA) and tannic acid (TA), <I>in vitro</I> and <I>in vivo</I> against <I>Salmonella</I> infection in mice. Both GA and TA showed antibacterial effects against <I>Salmonella</I> (<I>S.</I>) Typhimurium as well as inhibitory effects on the adherence, invasion, and intracellular growth of the pathogens in macrophages. Following a lethal dose of <I>Salmonella</I> infection in mice, reduced virulence in both GA- and TA-treated groups was observed based on reduced mortality rates. In the non-infected groups, the average weights of the spleens and livers of GA- or TA-treated mice were not significantly different with the control group. In addition, the average weights of these organs in all of the <I>Salmonella</I>-infected groups were not significantly different but the numbers of bacteria in the spleens and livers in both GA- and TA-treated mice were significantly reduced. The levels of cytokine production in non-infected mice revealed that GA-treated and TA-treated mice elicited an increased level of IFN-γ, and both IFN-γ and MCP-1, respectively, as compared with the PBS-treated group. These findings highlight the potential of GA and TA as alternatives for the treatment of salmonellosis and as supplements to conventional antimicrobial food additives.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Gallic acid (GA) and tannic acid (TA) showed antibacterial effects against <I>S.</I> Typhimurium. </LI> <LI> GA and TA showed a treatment effect against <I>S.</I> Typhimurium infection in a mouse model. </LI> <LI> GA-treated and TA-treated mice elicited an increased level of IFN-γ, and both IFN-γ and MCP-1, respectively. </LI> <LI> GA and TA could be used as potential alternatives for the treatment of salmonellosis. </LI> </UL> </P>

Differential Gene Retention in Plastids of Common Recent Origin

Reyes-Prieto, A.,Yoon, H. S.,Moustafa, A.,Yang, E. C.,Andersen, R. A.,Boo, S. M.,Nakayama, T.,Ishida, K.-i.,Bhattacharya, D. Oxford University Press 2010 Molecular biology and evolution Vol.27 No.7