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Rivas, Bernabé,L.,Pooley, S. Amalia,Pereira, Eduardo D.,Cid, Rocí,o,Luna, Maribel,Jara, M. Antonieta,Geckeler, Kurt E. Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of applied polymer science Vol.96 No.1
<P>The commercial polymers poly(ethylene imine) (PEI), poly(ethylene imine epichlorohydrin), and poly(dimethylamine-co-epichlorohydrin) were purified and fractionated by ultrafiltration. Their metal-ion-binding properties with respect to different ligand groups and the effect of the concentration on the retention properties were investigated. The amine ligands of the polymers formed the most stable complexes with the metal ions. In general, there was an effect of the pH and polymer fraction size on the retention properties. As the pH and polymer fraction size increased, the affinity to bind metal ions also increased. PEI had the highest metal-retention values, particularly at higher pHs, at which the amine groups were nonprotonated and could coordinate easily with the metal ions. Only Pb(II) was poorly retained. The affinity for all the metal ions, except Pb(II), increased significantly at pH 5. The metal-ion retention decreased quickly as the filtration factor increased, except for Cu(II), Co(II), Ni(II), Cd(II), and Zn(II) ions, which were retained by over 40% at a filtration factor of 4. For other metal ions such as Pb(II), Ca(II), and Mg(II), only 10% remained bound to the polymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 222–231, 2005</P>
Polyelectrolyte-assisted removal of metal ions with ultrafiltration
Rivas, Bernabé,L.,Pereira, Eduardo,Cid, Rocí,o,Geckeler, Kurt E. Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of applied polymer science Vol.95 No.5
<P>The water-soluble polymers poly(styrene sulfonic acid-co-maleic acid) and poly(acrylic acid-co-maleic acid) were investigated with respect to their metal-ion-binding ability with ultrafiltration. The studied metal ions included Ag(I), Cu(II), Ni(II), Co(II), Ca(II), Mg(II), Pb(II), Cd(II), Zn(II), Al(III), and Cr(III) ions. The retention properties of the polyelectrolytes for the metal ions depended strongly on the ligand type. As for the carboxylate ligands, with increasing concentration and pH, the metal-binding affinity increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1091–1099, 2005</P>
Rivas, Bernabé,L.,Pooley, S. Amalia,Pereira, Eduardo,Montoya, Erika,Cid, Rocí,o,Geckeler, Kurt E. John Wiley Sons, Ltd. 2006 Polymers for advanced technologies Vol.17 No.11
<P>The commercial, water-soluble poly(sodium anetole sulfonate) (PAnS), poly(sodium vinylsulfonate) (PVS), and poly(sodium 4-styrene sulfonate) (PStyS) were investigated as metal ion binding reagents using the liquid-phase-polymer-based retention (LPR) technique. The retention profiles of the following metal ions: Co(II), Ni(II), Ca(II), Mg(II), Pb(II), Cd(II), Zn(II), Cr(III), and Cu(II) were obtained by the LPR technique at pH 3, 5, and 7, and by changing the filtration factor Z from 0 to 10. As the pH increased, the affinity towards the metal ions increased slightly. By increasing the filtration factor Z, the affinity for the metal ions did not decrease significantly. This means that the ligand–metal interaction was strong, and it is not possible to break it by washing with water at the same pH of the filtration cell. Copyright © 2006 John Wiley & Sons, Ltd.</P>
Rivas, Bernabé,L.,Maureira, Antonio,Geckeler, Kurt E. Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of applied polymer science Vol.101 No.1
<P>Poly(4-acryloylmorpholine), poly(4-acryloylmorpholine-co-2-acrylamido-2-methyl-1-propane sulfonic acid), and poly(2-acrylamido-2-methyl-1-propane sulfonic acid) were synthesized by radical polymerization. The water-soluble polymers obtained, containing tertiary amino, amide, and sulfonic acid groups, were investigated, in view of their metal binding properties, as polychelatogens by using the liquid-phase polymer-based retention technique, under different experimental conditions. The metal ions investigated were Ag(I), Cu(II), Co(II), Ni(II), Cd(II), Pb(II), Zn(II), Cr(III), and Al(III). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 180–185, 2006</P>
Andrea Rivas-Castillo,Domancar Orona-Tamayo,Marlenne Gómez-Ramírez,Norma G. Rojas-Avelizapa 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.3
Bacillus megaterium strain MNSH1-9K-1, isolated from a high-metal content site in Guanajuato, Mexico, has the intrinsic capacity to remove vanadium (V) and nickel (Ni) from a petrochemical spent catalyst, and counteract the toxic effects produced in the cell due to the presence of oxidative stress. Since knowledge of the molecular components involved in the microbial resistance to spent catalysts is scarce, this study aimed to identify the proteins potentially involved in the enhanced resistance of a B. megaterium strain, during the removal of metals contained in a spent catalyst. Thus, the current research uses a proteomic approach to investigate and evidence the differences in the molecular resistance mechanisms of two B. megaterium strains, one isolated from a mining site and a wild type strain, when both are exposed to a spent catalyst. In addition, we studied their ability to eliminate nickel (Ni), vanadium (V), aluminum (Al) and molybdenum (Mo). The data presented here may contribute to the knowledge of the molecular mechanisms involved in the resistance of B. megaterium to high metal content wastes, as well as its potential utilization for the recovery of valuable industrial metals.
Effects of Steroid Hormone in Avian Follicles
Caicedo Rivas, R.E.,Nieto, M. Paz-Calderon,Kamiyoshi, M. Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.4
The aim of the present study was to examine the effects of testosterone (T) and estradiol-$17{\beta}$ ($E_2$) on the production of progesterone ($P_4$) by granulosa cells, and of the $E_2$ on the production of $P_4$ and T by theca internal cells. In the first experiment, granulosa cells isolated from the largest ($F_1$) and third largest ($F_3$) preovulatory follicle were incubated for 4 h in short-term culture system, $P_4$ production by granulosa cells of both $F_1$ and $F_3$ was increased in a dose-dependent manner by ovine luteinizing hormone (oLH), but not T or $E_2$. In the second experiment, $F_1$ and $F_3$ granulosa cells cultured for 48 h in the developed monolayer culture system were recultured for an additional 48 h with increasing doses of various physiological active substances existing in the ovary, including T and $E_2$. Basal $P_4$ production for 48 h during 48 to 96 h of the cultured was about nine fold greater by $F_1$ granulosa cells than by $F_3$ granulosa cells. In substances examined oLH, chicken vasoactive intestinal polypeptide (cVIP) and T, but not $E_2$, stimulated in a dose-dependent manner $P_4$ production in both $F_1$ and $F_3$ granulosa cells. In addition, when the time course of $P_4$ production by $F_1$ granulosa cells in response to oLH, cVIP, T and $E_2$ was examined for 48 h during 48 to 96 h of culture, although $E_2$ had no effect on $P_4$ production by granulosa cells of $F_1$ during the period from 48 to 96 h of culture, $P_4$ production with oLH was found to be increased at 4 h of the culture, with a maximal 9.14 fold level at 6 h. By contrast, $P_4$ production with cVIP and T increased significantly (p<0.05) from 8 and 12 h of the culture, respectively, with maximal 6.50 fold response at 12 h and 6, 48 fold responses at 36 h. Furthermore, when $F_1$ granulosa cells were precultured with $E_2$ for various times before 4 h culture with oLH at 96 h of culture, the increase in $P_4$ production in response to oLH with a dose-related manner was only found at a pretreatment time of more than 12 h. In the third experiment, theca internal cells of $F_1$, $F_2$ and the largest third to fifth preovulatory follicles ($F_{3-5}$) were incubated for 4 h in short-term culture system with increasing doses of $E_2$. The production of $P_4$ and T by theca internal cells were increased with the addition of $E_2$ of $10^{-6}M$. These increases were greater in smaller follicles. These results indicate that, in granulosa cells of the hen, T may have a direct stimulatory action in the long term on $P_4$ production, and on $E_2$ in long-term action which may enhance the sensitivity to LH for $P_4$ production, and thus, in theca internal cells, $E_2$ in short term action may stimulate the production of $P_4$ and T.
M.E. Rivas-Aguilar,N. Hernandez-Como,G. Gutierrez-Heredia,A. Sánchez-Martínez,M. Mireles Ramirez,M.A. Quevedo-López 한국물리학회 2018 Current Applied Physics Vol.18 No.7
In this work, the specific contact resistance (ρc) between amorphous indium-gallium-zinc-oxide (IGZO) semiconductor and different contact electrodes was obtained from thin film transistors (TFTs). Ti/Au (10/100 nm), aluminum doped zinc oxide (AZO, 100 nm) and indium tin oxide (ITO, 100 nm) were used as source/drain electrodes to fabricate IGZO TFTs. Chemical states of the contacts/semiconductor interfaces were examined by depth profile X-ray photoelectron spectroscopy (XPS) analysis to explain the origin of the differences on specific contact resistance. The lowest ρc achieved using Ti/Au was related to the formation of a TiOx interlayer due to oxygen atoms diffusing out from the semiconductor under layer, increasing the carrier concentration of IGZO at the interface and lowering the ρc. On the contrary, no interfacial reactions were observed between IGZO and AZO or ITO source/drain. However, IGZO resistivity increased with ITO contacts likely due to oxygen vacancies filling during ITO deposition. This fact seems to be the origin of the high contact resistance between IGZO and ITO, compared to IGZO-AZO and IGZO-Ti/Au interfaces.
In vitro Amoebicidal Activity of Borage (Borago officinalis) Extract on Entamoeba histolytica
Catalina Leos-Rivas,M. Julia Verde-Star,Lidia Osuna Torres,Azucena Oranday-Cardenas,Catalina Rivas-Morales,M. Porfiria Barron-Gonzalez,Mario R. Morales-Vallarta,Delia E. Cruz-Vega 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.7
Borage (Borago officinalis) is a plant with nutritional value that is also used in traditional medicine to treat gastrointestinal disease. This study investigated the amoebicidal activity of a methanol extract of borage. The 50% inhibitory concentration (IC_50) of the extract for Entamoeba histolytica was 33 μg/mL. The 50% lethal dose of the extract for brine shrimp was greater than 1,000 μg/mL. The IC_50 of the extract for Vero cells was 203.9 μg/mL. These results support the use of borage to prevent diseases associated with E. histolytica infection.