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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.
Reyes, Alisha Wehdnesday Bernardo,Arayan, Lauren Togonon,Huy, Tran Xuan Ngoc,Vu, Son Hai,Kang, Chang Keun,Min, Wongi,Lee, Hu Jang,Lee, John Hwa,Kim, Suk Elsevier 2019 Veterinary microbiology Vol.237 No.-
<P><B>Abstract</B></P> <P>We investigated the involvement of chemokine receptor type 4 (CXCR4) signaling on the outcome of <I>Brucella</I> (<I>B.</I>) <I>abortus</I> 544 infection in murine macrophages and in a mouse model. CXCR4 manipulation were first evaluated for <I>Brucella</I> invasion and intracellular survival efficiency, mitogen-activated protein kinases (ERK1/2, JNK, p38α) activation and generation of nitric oxide (NO), and then in the splenic bacterial proliferation and cytokine production in BALB/c mice. CXCR4 blockade is involved in the successful control of <I>Brucella</I> invasion, reduction of ERK1/2 phosphorylation and inhibition of nitric oxide release from macrophages. Furthermore, using a reported CXCR4-specific antagonist AMD3100 resulted in splenomegaly but attenuated <I>Brucella</I> proliferation in these organs with elevated serum levels of MCP-1, TNF and IL-12. These findings provide insights on the contribution of CXCR4 signaling in the phagocytic pathway and immune modulation during <I>B. abortus</I> infection.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CXCR4 blockade attenuated <I>B. abortus</I> invasion into RAW264.7 cells possibly via ERK pathway. </LI> <LI> CXCR4 blockade inhibited generation of NO in RAW264.7 cells during <I>B. abortus</I> infection. </LI> <LI> AMD3100 treatment in mice did not negatively affect body weight, serum ALT concentration or weight of spleens. </LI> <LI> AMD3100 treatment in mice displayed splenomegaly but reduced <I>B. abortus</I> proliferation with elevated serum levels of MCP-1, TNF and IL-12. </LI> </UL> </P>
Evolution pathway of CZTSe nanoparticles synthesized by microwave-assisted chemical synthesis
Reyes, Odin,Sanchez, Monica F.,Pal, Mou,Llorca, Jordi,Sebastian, P.J. Techno-Press 2017 Advances in nano research Vol.5 No.3
In this study we present the reaction mechanism of $Cu_2ZnSnSe_4$ (CZTSe) nanoparticles synthesized by microwave-assisted chemical synthesis. We performed reactions every 10 minutes in order to identify different phases during quaternary CZTSe formation. The powder samples were analyzed by x-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that in the first minutes copper phases are predominant, then copper and tin secondary phases react to form ternary phase. The quaternary phase is formed at 50 minutes while ternary and secondary phases are consumed. At 60 minutes pure quaternary CZTSe phase is present. After 60 minutes the quaternary phase decomposes in the previous ternary and secondary phases, which indicates that 60 minutes is ideal reaction time. The EDS analysis of pure quaternary nanocrystals (CZTSe) showed stoichiometric relations similar to the reported research in the literature, which falls in the range of Cu/(Zn+Sn): 0.8-1.0, Zn/Sn: 1.0-1.20. In conclusion, the evolution pathway of CZTSe synthesized by this novel method is similar to other synthesis methods reported before. Nanoparticles synthesized in this study present desirable properties in order to use them in solar cell and photoelectrochemical cell applications.
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>
Reyes Alisha Wehdnesday Bernardo,Kim Heejin,Huy Tran Xuan Ngoc,Nguyen Trang Thi,Min Wongi,Lee Dongho,Hur Jin,Lee John Hwa,김석 한국미생물·생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.9
This study investigated the contribution of lipoxygenase (LOX) inhibitors, nordihydroguaiaretic acid (NDGA), tetra-O-methyl nordihydroguaiaretic acid (M4N) and zileuton (ZIL), and thromboxane A2 (TXA2) inhibitor 4,5-diphenylimidazole (DPI) in the proliferation of Brucella abortus infection. None of the compounds affected the uptake of Brucella into the macrophages. We determined the effect of neutralizing leukotriene B4 (LTB4) receptor and showed that the uptake of the bacteria was inhibited at 30 min post-infection. M4N treatment attenuated intracellular survival of Brucella at 2 h post-incubation but it was not observed in the succeeding time points. DPI treatment showed reduced survival of Brucella at 24 h post-incubation while blocking LTB4 receptor was observed to have a lower intracellular growth at 48 h post-incubation suggesting different action of the inhibitors in the course of the survival of Brucella within the cells. Reduced proliferation of the bacteria in the spleens of mice was observed in animals treated with ZIL or DPI. Increased serum cytokine level of TNF-α and MCP-1 was observed in mice treated with M4N or ZIL while a lower IFN-γ level in ZIL-treated mice and a higher IL-12 serum level in DPI-treated mice were observed at 7 d postinfection. At 14 d post-infection, ZIL-treated mice displayed reduced serum level of IL-12 and IL-10. Overall, inhibition of 5-LOX or TXA2 or a combination therapy promises a potential alternative therapy against B. abortus infection. Furthermore, strong ligands for LTB4 receptor could also be a good candidate for the control of Brucella infection.