Carbamate Formation in the System (2-Methylpiperidine + Carbon Dioxide) by Raman Spectroscopy and X-ray Diffraction.

In aqueous solution, 2-methylpiperine (2-MP) has been proposed as a phase-separating amine for carbon-capture applications, whose carbamate is considered to be unstable due to steric hindrance. This paper demonstrates, for the first time, that the carbamate can be synthesized as the salt of the 2-methylpiperidinium cation (2-MPH+) and the 2-methylpiperidine- N-carboxylate anion (2-MPCOO-) by adding carbon dioxide gas to anhydrous liquid 2-MP at CO2/amine ratios α > 0.32 to yield well-defined prismatic crystals. Raman spectra have been measured for anhydrous liquid 2-MP and aqueous solutions of 2-MP and 2-MPH+Cl- at 298 K. The spectra of anhydrous liquid 2-MP, containing dissolved CO2 at lower CO2/amine ratios,. clearly showed the presence of 2-MPH+ and several unidentified bands that were attributed to the carbamate, 2-MPCOO-. Quantum chemical calculations at the B3LYP/6-311++G(d,p) level of theory yielded simulated Raman spectra consistent with the experimental spectra. The spectra show the methyl group of both liquid and aqueous 2-MP and that of aqueous 2-MPH+Cl- to be in the equatorial position. The crystal structure shows the same conformations in the solid state and confirms that Raman spectroscopy can be used to determine the conformation of 2-MP species in the liquid state and aqueous solutions.

Determination of derived volumetric properties and heat capacities at high pressures using two density scaling based equations of state. Application to dipentaerythritol hexa(3,5,5-trimethylhexanoate).

Reliable equations of state (EoS) together with heat capacities at atmospheric pressure make it possible to determine properties such as the isobaric thermal expansivity, compressibility, both isothermal and isentropic, high pressure isobaric heat capacities or speed of sound. In this work, we analysed the reliability of two density scaling based EoS, Power-Law Density Scaling (PLDS) and General Density Scaling (GDS), and the Tammann-Tait EoS to determine these quantities. For this aim, dipentaerythritol hexa(3,5,5-trimethylhexanoate), diPEiC9, was chosen because it has been recently proposed as a candidate to fill the gap of reference fluids suitable for high pressure viscometer calibration or their verification. New experimental densities measured between (283.15 and 398.15) K at pressures up to 70 MPa together with isobaric heat capacities between (282.93 and 399.92) K and thermal conductivities between (283 and 333) K at 0.1 MPa of diPEiC9 are reported. Literature relative volumes up to 400 MPa for this compound were also used. The three EoSs give rise to coherent values of the above properties. The most difficult property to describe is isobaric thermal expansivity for which the isobaric curves can present minima and/or maxima and the isotherm curves can cross at different pressures. The loci of the maxima of the isobaric thermal expansivity in p-T diagrams of the GDS and PLDS EoSs are very close.

Intestinal recruiting and activation profiles in peripheral blood mononuclear cells in response to pathogen-associated molecular patterns stimulation in patients with IBS.

BACKGROUND: Immune activation, increased Toll-like Receptors (TLR) expression, and gut epithelial diffusion of bacterial molecules have been reported in irritable bowel syndrome (IBS). Thus, we sought to relate these factors by analyzing gut homing (integrin α4ß7), intestinal recruiting (CCR5) and activation (CD28) phenotypes, and the cytokines and chemokines concentration in peripheral blood T-lymphocytes stimulated with TLR-ligands. METHODS: Twenty-one IBS-Rome II (1 PI-IBS) patients and 19 controls were studied. Isolated peripheral blood mononuclear cells were cultured with and without Escherichia coli lipopolysaccharide (LPS), Staphylococcus aureus peptidoglycan (PGN), and unmethylated cytosine-phosphate-guanine motifs (CpG). Phenotypes were investigated by flow cytometry and supernatant cytokines and chemokines were also measured. KEY RESULTS: After LPS, CCR5 expression in CD4⁺ α4ß7⁺ cells remained unchanged in IBS, but decreased in controls (p = 0.002), to lower levels than in IBS (Mean fluorescence intensity [MFI]: 1590 ± 126.9 vs 2417 ± 88.4, p < 0.001). There were less CD8(+) α4ß7⁺ CCR5⁺ cells (85.7 ± 1.5 vs 90.8 ± 0.9%, p = 0.006) after LPS and CD3⁺ α4ß7⁺ CCR5⁺ (40.0 ± 1.7 vs 51.2 ± 4.3%, p = 0.006) after PGN in controls. Also, after LPS, CD28 decreased in CD4⁺ α4ß7⁺ CCR5⁺ in IBS (MFI: 2337 ± 47.2 vs 1779 ± 179.2, p < 0.001), but not in controls. Cytokines and chemokines were similar, except for lower IL8/CXCL8 in the unstimulated condition in IBS (4.18, 95% CI: 3.94-4.42 vs 3.77, 3.59-3.95; p = 0.006). CONCLUSIONS & INFERENCES: Pathogen-associated molecular patterns stimulation of peripheral blood T cells expressing gut homing marker in IBS compared with controls resulted in an unsuccessful down-regulation of the co-expression of intestinal recruiting/residence phenotype and a state of activation. These findings support an interaction between an innate immune predisposition and microbial triggers, which may unleash or exacerbate IBS.

Absorption of carbon dioxide, nitrous oxide, ethane and nitrogen by 1-alkyl-3-methylimidazolium (C(n)mim, n = 2,4,6) tris(pentafluoroethyl)trifluorophosphate ionic liquids (eFAP).

We measured the densities of 1-alkyl-3-methylimidazolium (C(n)mim, n = 2,4,6) tris(pentafluoroethyl)trifluorophosphate ionic liquids (eFAP) as a function of temperature and pressure and their viscosities as a function of temperature. These ionic liquids are less viscous than those based in the same cations but with other anions such as bis(trifluoromethylsulfonyl)imide. The ionic liquids studied are only partially miscible with water, their solubility increasing with the size of the alkyl side-chain of the cation and with temperature (from x(H(2)O) = 0.20 ± 0.03 for [C(4)mim][eFAP] at 303.10 K to x(H(2)O) = 0.49 ± 0.07 for [C(6)mim][eFAP] at 315.10 K). The solubility of carbon dioxide, nitrous oxide, ethane, and nitrogen in the three ionic liquids was measured as a function of temperature and at pressures close to atmospheric. Carbon dioxide and nitrous oxide are the more soluble gases with mole fraction solubilities of the order of 3 × 10(-2) at 303 K. The solubility of these gases does not increase linearly with the size of the alkyl-side chain of the cation. The solubilities of ethane and nitrogen are much lower than those of carbon dioxide and nitrous oxide (mole fractions 60% and 90% lower, respectively). The higher solubility of CO(2) and N(2)O can be explained by more favorable interactions between the solutes and the polar region of the ionic liquids as shown by the enthalpies of solvation determined experimentally and by the calculation of the site-site solute-solvent radial distribution functions using molecular simulation.

[External validity of a relevant model for Irritable Bowel Syndrome (IBS) using chronic stress by water avoidance in Wistar rats]. / Validez externa de un modelo experimental para síndrome de intestino irritable (SII) mediante estrés crónico por evitación al agua en ratas Wistar.

BACKGROUND: Development of animal models has been one of the most remarkable achievements for Irritable Bowel Syndrome (IBS) research. These models need to exhibit face validity, construct and predictive validity, as well as internal (replicability) and external validity (generalizability). Among these models, chronic stress induced by water avoidance exposure (WA) has been validated in rats through increasing visceral hypersensitivity, motility impairment, anxiety and, colonic immune activity, all related to IBS. OBJECTIVE: To assess the external validity of WA indirectly on colonic motility in Wistar rats. METHOD: Ten male-Wistar rats were exposed to WA and compared with ten Wistar rats not exposed (controls). At the end of each exposure, the quantity of fecal pellets were determined and considered as a sign of autonomic regulation of colonic motility. Data was analyzed with a general linear model for repeated measures. RESULTS: Rats exposed to WA had higher number or pellets than controls: 7.46 ± 0.45 (95%CI: 6.51, 8.41) vs. 2.88 ± 0.45 (1.93, 3.83), p < 0.001. The higher number of pellets was related to WA exposure as there were no other significant interactions. In both groups, the number of pellets was higher during the first day and then decreased progressively. CONCLUSIONS: Chronic stress induced through WA in Wistar rats, exhibits external validity as an experimental model for IBS research and our findings of increased number of fecal pellets coincide with the appearance hypermotility related to IBS. The model is optimum for research studies on this disorder.