Concentration distributions during flow of confined flowing polymer solutions at finite concentration: slit and grooved channel

Hernandez-Ortiz, Juan P.,Ma, Hong-Bo,de Pablo, Juan J.,Graham, Michael D. The Korean Society of Rheology 2008 Korea-Australia rheology journal Vol.20 No.3

Simulations of solutions of flexible polymer molecules during flow in simple or complex confined geometries are performed. Concentrations from ultradilute up to near the overlap concentration are considered. As concentration increases, the hydrodynamic migration effects observed in dilute solution unidirectional flows (Couette flow, Poiseuille flow) become less prominent, virtually vanishing as the overlap concentration is approached. In a grooved channel geometry, the groove is almost completely depleted of polymer chains at high Weissenberg number in the dilute limit, but at finite concentration this depletion effect is dramatically reduced. Only upon inclusion of hydrodynamic interactions can these phenomena be properly captured.

Concentration distributions during flow of confined flowing polymer solutions at finite concentration: slit and grooved channel

Juan P. Hernandez-Ortiz,Hongbo Ma,Juan J. de Pablo,Michael D. Graham 한국유변학회 2008 Korea-Australia rheology journal Vol.20 No.3

Simulations of solutions of flexible polymer molecules during flow in simple or complex confined geometries are performed. Concentrations from ultradilute up to near the overlap concentration are considered. As concentration increases, the hydrodynamic migration effects observed in dilute solution unidirectional flows (Couette flow, Poiseuille flow) become less prominent, virtually vanishing as the overlap concentration is approached. In a grooved channel geometry, the groove is almost completely depleted of polymer chains at high Weissenberg number in the dilute limit, but at finite concentration this depletion effect is dramatically reduced. Only upon inclusion of hydrodynamic interactions can these phenomena be properly captured.

Final report on key comparison CCQM-K73: Amount content of H⁺ in hydrochloric acid (0.1 mol kg⁻¹)

Pratt, Kenneth W,Ortiz-Aparicio, Jose Luis,Matehuala-Sanchez, Francisco Javier,Pawlina, Monika,Kozlowski, Wladyslaw,Borges, Paulo P,da Silva Junior, Wiler B,Borinsky, Mó,nica B,Hernandez-Mabel P Springer-Verlag 2013 Metrologia Vol.50 No.-

<P>This key comparison (KC), CCQM-K73, was performed to demonstrate the capability of the participating National Metrology Institutes (NMIs) to measure the amount content of H<SUP>+</SUP>, ν<SUB>H<SUP>+</SUP></SUB>, in an HCl solution with a nominal ν<SUB>H<SUP>+</SUP></SUB> of 0.1 mol kg<SUP>−1</SUP>. The comparison was a joint activity of the Electrochemical Working Group (EAWG) and Inorganic Analysis Working Group (IAWG) of the CCQM and was coordinated by NIST (USA) and CENAM (Mexico).</P><P>The agreement of the results was not commensurate with the claimed uncertainties of the subset of participants that claimed small uncertainties for this determination. A workshop on technical issues relating to the CCQM-K73 measurements was conducted at the joint IAWG-EAWG meeting at the Bureau International des Poids et Mesures (BIPM), Paris (Sèvres) in April 2010. Several possible sources of bias were investigated, but none could explain the observed dispersion among the participants' results.</P><P>In the absence of a specific cause for the dispersion, the IAWG and EAWG decided to assign a Key Comparison Reference Value, KCRV, and standard uncertainty of the KCRV, u<SUB>KCRV</SUB>, based on the DerSimonian–Laird statistical estimator. The u<SUB>KCRV</SUB> is dominated by the between-laboratory scatter of results in CCQM-K73. The uncertainty estimates from the participants with the lowest reported uncertainties remain unsupported by this KC.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

Effect of Fodder Tree Species with Condensed Tannin Contents on In vitro Methane Production

Vazquez, Ernestina Gutierrez,Medina, Leonardo Hernandez,Benavides, Liliana Marquez,Caratachea, Aureliano Juarez,Razo, Guillermo Salas,Burgos, Armin Javier Ayala,Rodriguez, Ruy Ortiz Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.1

The objective was to evaluate the effect of fodder tree species (FTS) with condensed tannin contents: Cordia elaeagnoides, Platymiscium lasiocarpum, Vitex mollis, and Haematoxylon brasiletto, on in vitro methane ($CH_4$) production at 24 h post incubation. The analysis was performed using the in vitro gas production technique, with three levels of inclusion/species: 600, 800, and 1,000 mg and with 4 replicates/species/level of inclusion. The substrate was incubated at $39^{\circ}C$, and the gas and $CH_4$ production were recorded at 4, 8, 12, and 24 h post incubation. The data collected was analyzed through Pearson correlation, polinomial regression and fixed effects models. There were negative correlations between FTS-total gas volume (r = -0.40; p<0.001); FTS-volume of $CH_4$ produced (r = -0.40; p<0.001) and between the inclusion level-volume of $CH_4$ produced (r = -0.20; p<0.001). As well as a positive correlation between hours post incubation-total gas volume (r = 0.42; p<0.001) and between hours post incubation-volume of $CH_4$ produced (r = 0.48; p<0.001). The FTS: C. elaeagnoides, V. mollis, and H. brasiletto have potential, in the three inclusion levels analyzed, to reduce $CH_4$ emission on in vitro trials (>32.7%), taking into account the total $CH_4$ production at 24 h of the forage used as reference (Avena sativa). It's suggested that C. elaeagnoides-according to its crude protein, neutral detergent fiber, and condensed tannins content- is the best alternative within the FTS analyzed, for feeding ruminants and for the control of $CH_4$ emissions during the dry season.

Evidence for the Participation of ATP-sensitive Potassium Channels in the Antinociceptive Effect of Curcumin

Paz-Campos, Marco Antonio De,Chavez-Pina, Aracely Evangelina,Ortiz, Mario I,Castaneda-Hernandez, Gilberto The Korean Pain Society 2012 The Korean Journal of Pain Vol.25 No.4

Background: It has been reported that curcumin, the main active compound of Curcuma longa, also known as turmeric, exhibits antinociceptive properties. The aim of this study was to examine the participation of ATP-sensitive potassium channels ($K_{ATP}$ channels) and, in particular, that of the L-arginine-nitric oxide-cyclic GMP-$K_{ATP}$ channel pathway, in the antinociceptive effect of curcumin. Methods: Pain was induced by the intraplantar injection of 1% formalin in the right hind paw of Wistar rats. Formalin-induced flinching behavior was interpreted as an expression of nociception. The antinociceptive effect of oral curcumin was explored in the presence and absence of local pretreatment with L-NAME, an inhibitor of nitric oxide synthase, ODQ, an inhibitor of soluble guanylyl cyclase, and glibenclamide, a blocker of $K_{ATP}$ channels. Results: Oral curcumin produced a dose-dependent antinociceptive effect in the 1% formalin test. Curcumin-induced antinociception was not altered by local L-NAME or ODQ, but was significantly impaired by glibenclamide. Conclusions: Our results confirm that curcumin is an effective antinociceptive agent. Curcumin-induced antinociception appears to involve the participation of $K_{ATP}$ channels at the peripheral level, as local injection of glibenclamide prevented its effect. Activation of $K_{ATP}$ channels, however, does not occur by activation of the L-arginine-nitric oxide-cGMP-$K_{ATP}$ channel pathway.

Evidence for the Participation of ATP-sensitive Potassium Channels in the Antinociceptive Effect of Curcumin

( Marco Antonio ),( Paz Campos ),( Aracely Evangelina ),( Chavez Pina ),( Mario I Ortiz ),( Gilberto ),( Castaneda Hernandez ) 대한통증학회 2012 The Korean Journal of Pain Vol.25 No.4

Background: It has been reported that curcumin, the main active compound of Curcuma longa, also known as turmeric, exhibits antinociceptive properties. The aim of this study was to examine the participation of ATP-sensitive potassium channels (KATP channels) and, in particular, that of the L-arginine-nitric oxide-cyclic GMP-KATP channel pathway, in the antinociceptive effect of curcumin. Methods: Pain was induced by the intraplantar injection of 1% formalin in the right hind paw of Wistar rats. Formalin-induced flinching behavior was interpreted as an expression of nociception. The antinociceptive effect of oral curcumin was explored in the presence and absence of local pretreatment with L-NAME, an inhibitor of nitric oxide synthase, ODQ, an inhibitor of soluble guanylyl cyclase, and glibenclamide, a blocker of KATP channels. Results: Oral curcumin produced a dose-dependent antinociceptive effect in the 1% formalin test. Curcumin-induced antinociception was not altered by local L-NAME or ODQ, but was significantly impaired by glibenclamide. Conclusions: Our results confirm that curcumin is an effective antinociceptive agent. Curcumin-induced antinociception appears to involve the participation of KATP channels at the peripheral level, as local injection of glibenclamide prevented its effect. Activation of KATP channels, however, does not occur by activation of the L-arginine-nitric oxide-cGMP- KATP channel pathway.