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Journal articles on the topic 'High pressure reactivity'

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Author: Grafiati

Published: 10 March 2023

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1

Citroni, Margherita, Matteo Ceppatelli, Roberto Bini, and Vincenzo Schettino. "High-pressure reactivity of propene." Journal of Chemical Physics 123, no. 19 (November 15, 2005): 194510. http://dx.doi.org/10.1063/1.2109947.

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2

Ceppatelli, Matteo, Marco Frediani, and Roberto Bini. "High-Pressure Reactivity ofl,l-Lactide." Journal of Physical Chemistry B 115, no. 10 (March 17, 2011): 2173–84. http://dx.doi.org/10.1021/jp1110136.

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3

Fanetti, Samuele, Matteo Ceppatelli, Margherita Citroni, and Roberto Bini. "High-Pressure Photoinduced Reactivity of CH3OH and CD3OH." Journal of Physical Chemistry C 116, no. 3 (October 18, 2011): 2108–15. http://dx.doi.org/10.1021/jp205563d.

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4

Ceppatelli, Matteo, Samuele Fanetti, Margherita Citroni, and Roberto Bini. "Photoinduced Reactivity of Liquid Ethanol at High Pressure." Journal of Physical Chemistry B 114, no. 47 (December 2, 2010): 15437–44. http://dx.doi.org/10.1021/jp106516t.

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5

Sanloup, Chrystele, Celine Crepisson, Clemence Leroy, Marc Blanchard, Helene Bureau, and Laurent Cormier. "Reactivity of heavy noble gases under high pressure." Acta Crystallographica Section A Foundations and Advances 75, a2 (August 18, 2019): e252-e252. http://dx.doi.org/10.1107/s2053273319093045.

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6

Eldridge, M. W., A. Podolsky, R. S. Richardson, D. H. Johnson, D. R. Knight, E. C. Johnson, S. R. Hopkins, et al. "Pulmonary hemodynamic response to exercise in subjects with prior high-altitude pulmonary edema." Journal of Applied Physiology 81, no. 2 (August 1, 1996): 911–21. http://dx.doi.org/10.1152/jappl.1996.81.2.911.

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Individuals with a prior history of (susceptible to high altitude pulmonary edema (HAPE-S) have high resting pulmonary arterial pressures, but little data are available on their vascular response to exercise. We studied the pulmonary vascular response to exercise in seven HAPE-S and nine control subjects at sea level and at 3,810 m altitude. At each location, both normoxic (inspired PO2 = 148 Torr) and hypoxic (inspired PO2 = 91 Torr) studies were conducted. Pulmonary hemodynamic measurements included pulmonary arterial and pulmonary arterial occlusion pressures. A multiple regression analysis demonstrated that the pulmonary arterial pressure reactivity to exercise was significantly greater in the HAPE-S group. This reactivity was not influenced by altitude or oxygenation, implying that the response was intrinsic to the pulmonary circulation. Pulmonary arterial occlusion pressure reactivity to exercise was also greater in the HAPE-S group, increasing with altitude but independent of oxygenation. These findings suggest an augmented flow-dependent pulmonary vasoconstriction and/or a reduced vascular cross-sectional area in HAPE-S subjects.

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7

Chuliá-Jordán, Raquel, David Santamaría-Pérez, Tomás Marqueño, Javier Ruiz-Fuertes, and Dominik Daisenberger. "Oxidation of High Yield Strength Metals Tungsten and Rhenium in High-Pressure High-Temperature Experiments of Carbon Dioxide and Carbonates." Crystals 9, no. 12 (December 17, 2019): 676. http://dx.doi.org/10.3390/cryst9120676.

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The laser-heating diamond-anvil cell technique enables direct investigations of materials under high pressures and temperatures, usually confining the samples with high yield strength W and Re gaskets. This work presents experimental data that evidences the chemical reactivity between these refractory metals and CO2 or carbonates at temperatures above 1300 °Ϲ and pressures above 6 GPa. Metal oxides and diamond are identified as reaction products. Recommendations to minimize non-desired chemical reactions in high-pressure high-temperature experiments are given.

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8

Ray, Paramita, Jennifer L. Gray, John V. Badding, and Angela D. Lueking. "High-Pressure Reactivity of Triptycene Probed by Raman Spectroscopy." Journal of Physical Chemistry B 120, no. 42 (October 17, 2016): 11035–42. http://dx.doi.org/10.1021/acs.jpcb.6b05120.

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9

Scaccia, Silvera. "Sulcis coal char reactivity under high-pressure H 2." Fuel Processing Technology 128 (December 2014): 441–48. http://dx.doi.org/10.1016/j.fuproc.2014.07.016.

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10

Binns, Jack, Philip Dalladay-Simpson, Mengnan Wang, Eugene Gregoryanz, and Ross T. Howie. "Enhanced Reactivity of Lithium and Copper at High Pressure." Journal of Physical Chemistry Letters 9, no. 11 (May 22, 2018): 3149–53. http://dx.doi.org/10.1021/acs.jpclett.8b01350.

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11

Spooner, Jacob, Brandon Smith, and Noham Weinberg. "Effect of high pressure on the topography of potential energy surfaces." Canadian Journal of Chemistry 94, no. 12 (December 2016): 1057–64. http://dx.doi.org/10.1139/cjc-2016-0295.

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Properties and reactivity of chemical compounds change dramatically at elevated pressures. Since kinetics and mechanisms of condensed-phase reactions are described in terms of their potential energy (PESs) or Gibbs energy (GESs) surfaces, chemical effects of high pressure can be assessed through analysis of pressure-induced deformations of GESs of solvated reaction systems. We discuss general trends expected for such changes and use quantum mechanical calculations to construct PESs of compressed species for hydrogen and methyl transfer reactions.

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12

Casati, Nicola, Andrew Jephcoat, Heribert Wilhelm, and Piero Macchi. "Chemical reactivity at high pressure: the ordered polymerization of oxalic acid." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C898. http://dx.doi.org/10.1107/s2053273314091013.

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Pressure is known to trigger unusual chemical reactivity in molecular solids. In particular, small molecules containing unsaturated bonds are subject to oligo- or polymerization, effectively synthesizing new compounds. These are tipically energetic materials which can be amorphous, as in the case of carbon monoxide,[1] or crystalline, as for carbon dioxide phase V.[2] In more complex molecular systems, where unsaturated bonds can be only one of the present moieties, stereo-controlled reactivity can be exploited to synthesize topo-tactic structures. We performed a synchrotron single crystal experiment on oxalic acid dihydrate up to 54.7 GPa, using He as pressure transmitting medium to ensure hydrostatic behavior. This is, to the best of our knowledge, the highest pressure ever achieved in a single crystal study on an organic molecule. It had been reported that the species undergoes a proton transfer at mild pressures,[3] and further compression confirms the major role played by hydrogen bonds. After the proton transfer, the species undergoes two phase transitions, caused mainly by a rearrangement of hydrogen bonding patterns, that does not demage the singly crystal nature of the sample. At ~40 GPa an initial bending of the flat oxalic molecule is observed, sign of an enhanced nucleophilic interaction between one oxygen and the carbon of a neighbor molecule. At the highest pressure achieved, a further phase transition is observed. Although the crystallinity is decreased, the new unit cell shows a drastic shrinking in one specific direction. Periodic DFT calculations reveal this metric is compatible with an ordered polymerization of the oxalic acid created by a nucleophilic addition: a monodimensional covalent organic framework is the resulting material (figure). This observation, unique up to now in its kind, is of high relevance for crystal engineering and highlights the potential of high pressure to stimulate new chemistry.

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13

Krishnamoorthy, Vijayaragavan, and Sarma V. Pisupati. "Effect of Temperature, Pressure, Feed Particle Size, and Feed Particle Density on Structural Characteristics and Reactivity of Chars Generated during Gasification of Pittsburgh No.8 Coal in a High-Pressure, High-Temperature Flow Reactor." Energies 12, no. 24 (December 14, 2019): 4773. http://dx.doi.org/10.3390/en12244773.

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The gasification behavior of coal under high-temperature and high-pressure conditions is important from the perspective of designing and optimizing high efficiency gasifiers and troubleshooting existing gasifiers. The effect of feed particle size, density, temperature, and pressure on char porous structure, morphology, reflectance, and reactivity under conditions relevant to entrained-flow gasification was investigated. The chars were generated over a range of temperatures (1100, 1300, and 1400 °C at 11.3 bar for the −150 + 106 µm fraction), pressures (3.4, 6.2, 11.3, 15.5, and 21.7 bar at 1300 °C for the −150 + 106 µm fraction), for various size fractions (−106 + 75, −150 + 106, −212 + 150, −420 + 212 µm at 1300 °C and 11.3 bar), and density fractions (<1.3, 1.3–1.6, >1.6g/cc for the −106 + 75 µm at 1300 °C and 11.3 bar) of Pittsburgh No.8 bituminous coal using a high-pressure, high-temperature flow reactor (HPHTFR) in a equimolar mixture of CO2 and N2. Chars were characterized for conversion, morphology, thermal swelling ratio, and reactivity using ash tracer technique, oil immersion microscopy, tap density technique, and a thermogravimetric analyzer, respectively, and the results were statistically analyzed to determine for effects by feed particle density, feed particle size, temperature, and pressure. The results showed that the conversion was most affected by temperature, followed by feed particle size, pressure, and feed particle density. In the case of structural characteristics (i.e., thermal swelling ratio and group-I char concentration), feed particle density affected group-I concentration, while both feed particle size and feed particle density affected thermal swelling ratio. Variation in vitrinite content and fragmentation affected the thermal swelling ratio and group-I char concentration. In the case of intrinsic reactivity, particle density showed the largest effect, followed by temperature, particle size, and pressure. An increase in reflectance and temperature was found to inversely affect intrinsic reactivity.

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14

Demazeau, Gérard. "High Pressure and Chemical Bonding in Materials Chemistry." Zeitschrift für Naturforschung B 61, no. 7 (July 1, 2006): 799–807. http://dx.doi.org/10.1515/znb-2006-0705.

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Materials chemistry under high pressures is an important research area opening new routes for stabilizing novel materials or original structures with different compositions (oxides, oxoborates, nitrides, nitridophosphates, sulfides,. . .).Due to the varieties of chemical compositions and structures involved, high pressure technology is also an important tool for improving the investigations on chemical bonding and consequently the induced physico-chemical properties.Two different approaches can be described: (i) the chemical bond is pre-existing and in such a case, high pressures lead to structural transformations, (ii) the chemical bond does not exist and high pressures are able to help the synthesis of novel materials. In both cases the condensation effect (ΔV < 0 between precursors and the final product) is the general rule. In addition, through the improvement of the reactivity, high pressures can lead to materials that are not reachable through other chemical routes.

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15

Cooper, B., M. Ahlquist, R. M. Friedman, B. Loughner, and M. Heft. "Properties of high-threshold mechanoreceptors in the oral mucosa. I. Responses to dynamic and static pressure." Journal of Neurophysiology 66, no. 4 (October 1, 1991): 1272–79. http://dx.doi.org/10.1152/jn.1991.66.4.1272.

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1. Mechanical response properties of high-threshold mechanoreceptors (HTMs) of the goat oral mucosa were determined by single-unit recording from the palatine and alveolar nerves and from the trigeminal ganglion. The following observations were made. 2. HTMs of the oral mucosa could be separated into two subgroups on the basis of their threshold to mechanical stimulation. Intense pressure receptors (IPRs) comprised a group of A-delta afferents with thresholds of 2-16 g. Mechanonociceptors (MNs) comprised a group of relatively slowly conducting afferents (A-delta and C-fibers) with a higher threshold range (16-300 g). 3. In most instances, MNs lacked pressure-transducing capacity. Tests of reactivity to dynamically or statically applied stimuli revealed that significant functions were rarely fit between MN activity and pressure (4/20 cases). 4. IPRs differed from MNs by their pressure-transducing properties. The afferent response interval was in inverse proportion to the applied pressure. Significant pressure interval functions were fit in 16/20 cases. The relationship between pressure and response interval was best described by power functions. 5. Tests of reactivity to dynamically or statically applied stimuli revealed that IPRs preferred static pressure. Tighter fits and steeper slopes were observed in power functions fit to data generated by statically applied stimuli (mean fitted function, dynamic test: LnISI = -0.97 LnP + 3.4; mean fitted function, static test: LnISI = -1.6 LnP + 4.71). 6. Pressures-frequency thresholds (PFTs), asymptotes (PFAs), and mean response intervals (MRIs) were determined for IPRs from the static test series. The first two values are the pressures that produce the lower and upper limits of response frequency of mucosal HTMs (mean PFT, 1.48 N/mm2; mean PFA, 3.34 N/mm2). The MRI (28 ms) is simply computed from the function. When PFTs and PFAs are combined with activation threshold and power functions, they provide a relatively complete description of the range and form of reactivity of the IPR of the oral mucosa.

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16

Ciabini, Lucia, Mario Santoro, Roberto Bini, and Vincenzo Schettino. "High pressure reactivity of solid benzene probed by infrared spectroscopy." Journal of Chemical Physics 116, no. 7 (February 15, 2002): 2928–35. http://dx.doi.org/10.1063/1.1435570.

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17

Ceppatelli, Matteo, Samuele Fanetti, and Roberto Bini. "Photoinduced Reactivity of Red Phosphorus and Ethanol at High Pressure." Journal of Physical Chemistry C 117, no. 25 (June 18, 2013): 13129–35. http://dx.doi.org/10.1021/jp403398w.

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18

Mediavilla, C., J. Tortajada, and V. G. Baonza. "Modeling high pressure reactivity in unsaturated systems: Application to dimethylacetylene." Journal of Computational Chemistry 30, no. 3 (February 2009): 415–22. http://dx.doi.org/10.1002/jcc.21068.

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19

Bragin, Denis E., Gloria L. Statom, Howard Yonas, Xingping Dai, and Edwin M. Nemoto. "Critical Cerebral Perfusion Pressure at High Intracranial Pressure Measured by Induced Cerebrovascular and Intracranial Pressure Reactivity." Critical Care Medicine 42, no. 12 (December 2014): 2582–90. http://dx.doi.org/10.1097/ccm.0000000000000655.

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20

Machon, D., D. Daisenberger, E. Soignard, G. Shen, T. Kawashima, E. Takayama-Muromachi, and P. F. McMillan. "High pressure - high temperature studies and reactivity of γ-Mo2N and δ-MoN." physica status solidi (a) 203, no. 5 (April 2006): 831–36. http://dx.doi.org/10.1002/pssa.200521008.

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21

Scrogin, K. E., D. C. Hatton, and D. A. McCarron. "The interactive effects of dietary sodium chloride and calcium on cardiovascular stress responses." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 261, no. 4 (October 1, 1991): R945—R949. http://dx.doi.org/10.1152/ajpregu.1991.261.4.r945.

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Blood pressure increases associated with salt loading in the spontaneously hypertensive rat (SHR) are attenuated with increased dietary calcium. To assess the cardiovascular effects of these nutrients during stress, blood pressure and sympathoadrenal responses to stress were compared in salt-sensitive SHRs fed diets containing normal (0.73%) or high (8.0%) NaCl combined with either low (0.2%) or high (2.0%) calcium. NaCl-loaded rats showed increased blood pressure and exaggerated plasma epinephrine changes during restraint stress. Elevated blood pressure responses to exogenous NE were also observed with high salt intake. Supplementary calcium reduced blood pressure and attenuated the hypertensive effect of NaCl during restraint stress. Animals fed the high calcium diets had lower plasma epinephrine levels while vascular reactivity was not affected. The results indicate that increased sympathoadrenal activity and vascular reactivity contribute to elevated blood pressure and exaggerated pressor responses produced by NaCl loading in the salt-sensitive SHR. However, the hypotensive effects of dietary calcium appear to be related to sympathoadrenal activity but not vascular reactivity.

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22

Enouri, Saad, Gabrielle Monteith, and Ron Johnson. "Characteristics of myogenic reactivity in isolated rat mesenteric veins." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 300, no. 2 (February 2011): R470—R478. http://dx.doi.org/10.1152/ajpregu.00491.2010.

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Mechanisms of mechanically induced venous tone and its interaction with the endothelium and key vasoactive neurohormones are not well established. We investigated the contribution of the endothelium, l-type voltage-operated calcium channels (l-VOCCs), and PKC and Rho kinase to myogenic reactivity in mesenteric vessels exposed to increasing transmural pressure. The interaction of myogenic reactivity with norepinephrine (NE) and endothelin-1 (ET-1) was also investigated. Pressure myography was used to study isolated, cannulated, third-order rat mesenteric small veins and arteries. NE and ET-1 concentration response curves were constructed at low, intermediate, and high transmural pressures. Myogenic reactivity was not altered by nitric oxide synthase inhibition with Nω-nitro-l-arginine (l-NNA; 100 μM) or endothelium removal in both vessels. l-VOCCs blockade (nifedipine, 1 μM) completely abolished arterial tone, while only partially reducing venous tone. PKC (chelerythrine, 2.5 μM) and Rho kinase (Y27632, 3 μM) inhibitors largely abolished venous and arterial myogenic reactivity. There was no significant difference in the sensitivity of NE or ET-1-induced contractions within vessels. However, veins were more sensitive to NE and ET-1 when compared with corresponding arteries at low, intermediate, and high transmural pressures, respectively. These results suggest that 1) myogenic factors are important contributors to net venous tone in mesenteric veins; 2) PKC and Rho activation are important in myogenic reactivity in both vessels, while l-VOCCs play a limited role in the veins vs. the arteries, and the endothelium does not appear to modulate myogenic reactivity in either vessel type; and 3) mesenteric veins maintain an enhanced sensitivity to NE and ET-1 compared with the arteries when studied under conditions of changing transmural distending pressure.

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23

Mugnai, Martina, Gianni Cardini, and Vincenzo Schettino. "High pressure reactivity of propene by first principles molecular dynamics calculations." Journal of Chemical Physics 120, no. 11 (March 15, 2004): 5327–33. http://dx.doi.org/10.1063/1.1647051.

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24

Fermoso, J., C. Stevanov, B. Moghtaderi, B. Arias, C. Pevida, M. G. Plaza, F. Rubiera, and J. J. Pis. "High-pressure gasification reactivity of biomass chars produced at different temperatures." Journal of Analytical and Applied Pyrolysis 85, no. 1-2 (May 2009): 287–93. http://dx.doi.org/10.1016/j.jaap.2008.09.017.

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25

Spooner, Jacob, Heather Wiebe, Miranda Louwerse, Brandon Reader, and Noham Weinberg. "Theoretical analysis of high-pressure effects on conformational equilibria." Canadian Journal of Chemistry 96, no. 2 (February 2018): 178–89. http://dx.doi.org/10.1139/cjc-2017-0411.

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Along with temperature, pressure is the most important physical parameter determining the thermodynamic properties and reactivity of chemical systems. In this work, we discuss the effects of high pressure on conformational properties of organic molecules and propose an approach toward calculation of conformational volume changes based on molecular dynamics simulations. The results agree well with the experimental data. Furthermore, we demonstrate that pressure can be used as an instrument for fine-tuning of molecular conformations and to propel a properly constructed molecular rotor possessing a suitable combination of energy and volume profiles.

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26

Bermúdez, Vicente, Vicente Macián, David Villalta, and Lian Soto. "Impact of injection settings on gaseous emissions and particle size distribution in the dual-mode dual-fuel concept." International Journal of Engine Research 21, no. 4 (April 24, 2019): 561–77. http://dx.doi.org/10.1177/1468087419844413.

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Reactivity controlled compression ignition concept has been highlighted among the low temperature combustion strategies. However, this combustion strategy presents some problems related to high levels of hydrocarbon and carbon monoxide emissions at low load and high-pressure rise rate at high load. Therefore, to diminish these limitations, the dual-mode dual-fuel concept has been presented as an excellent alternative. This concept uses two fuels of different reactivity and switches from a dual-fuel fully premixed strategy (based on the reactivity controlled compression ignition concept) during low load to a diffusive nature during high load operation. However, the success of dual-mode dual-fuel concept depends to a large extent on the low reactivity/high reactivity fuel ratio and the injection settings. In this study, parametric variations of injection pressure and injection timing were experimentally performed to analyze the effect over each combustion process that encompasses the dual-mode dual-fuel concept and its consequent impact on gaseous and particles emissions, including an analysis of particle size distribution. The experimental results confirm how the use of an adequate injection strategy is indispensable to obtain low exhaust emission and a balance between the different pollutants. In the fully premixed reactivity controlled compression ignition strategy, the particles concentrations were dominated by nucleation mode; however, the increase in injection pressure and the advance of the diesel main injection timing provided a simultaneous reduction of nitrogen oxide and solid particles (accumulation mode). During the highly premixed reactivity controlled compression ignition strategy, the accumulation-mode particles increased, and their concentrations were higher when the diesel main injection timing advanced and injection pressure decreased, as well as there was a slight increase in nitrogen oxide emissions. Finally, in the dual-fuel diffusion strategy, the concentrations of accumulation-mode particles were higher and there was a considerable increase of these particles with the advance of the diesel main injection timing and the reduction of the injection pressure, while the nitrogen oxide emissions decreased.

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27

Gut, Vladimír, Zinaida G. Makarova, Alexander S. Molokoedov, and Victor M. Zhulin. "Peptide synthesis under high pressure by aminolysis of methyl and phenyl esters." Collection of Czechoslovak Chemical Communications 55, no. 9 (1990): 2317–20. http://dx.doi.org/10.1135/cccc19902317.

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High pressure may, depending on solvent, enhance the reactivity of methyl and phenyl ester of the N-protected dipeptide Ala-Ala with the amino component, valine tert-butyl ester, yielding the protected tripeptide. Results of this reaction in several solvents are discussed.

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28

Fukunaga, Tetsu, Paul Davies, Leilei Zhang, Yoshie Hashida, and Etsuro K. Motoyama. "Prolonged high intermittent positive-pressure ventilation induces airway remodeling and reactivity in young rats." American Journal of Physiology-Lung Cellular and Molecular Physiology 275, no. 3 (September 1, 1998): L567—L573. http://dx.doi.org/10.1152/ajplung.1998.275.3.l567.

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We postulated that prolonged exposure to intermittent positive-pressure ventilation (IPPV) with high pressure (HIPPV) alone without hyperoxia promotes the development of airway hyperresponsiveness and remodeling. To test this hypothesis, young rats were ventilated under halothane anesthesia with HIPPV (maximum inspiratory pressure at 32–35 cmH2O in 70% nitrous oxide and 30% O2) for 3.5–4 h daily for 6 days. Control rats were ventilated with low IPPV (maximum inspiratory pressure < 13 cmH2O) during the same time period with the same gas mixture. With the use of tracheal rings isolated from these rats and a setup in tissue baths, contractile responses to carbachol (10−6 to 10−2 mM), 5-hydroxytryptamine (5-HT; 10−9 to 10−5 mM) and KCl (1–100 mM) were examined isometrically. In tracheal rings from HIPPV rats compared with low-pressure IPPV rats, the concentration tension curves showed a significantly enhanced response to all agonists ( P < 0.005). Sensitivity to carbachol, 5-HT, and KCl was also significantly increased ( P < 0.05) compared with control rats as evidenced by decreases in EC50. Maximum tension (reactivity) to 5-HT and KCl in the HIPPV group increased significantly ( P < 0.05), and there was a trend ( P = 0.07) toward increased reactivity to carbachol in this group as well. Histological examinations of tracheal rings demonstrated epithelial squamous metaplasia in the HIPPV group. Morphometric studies demonstrated tracheal smooth muscle thickening ( P < 0.05) without changes in the thickness of the mucosa or the lamina propria. When contractile responses were normalized for the smooth muscle cross-sectional area (i.e., stress), reactivity to all contractile agents was reduced, whereas reactivity to 5-HT still demonstrated significant increase ( P < 0.005). Sensitivity of tracheal segments to all three agents was not affected by this normalization. These findings suggest that prolonged exposure to HIPPV without hyperoxia and the resultant overdistension of lung tissues (volutrauma) induced airway remodeling and airway hyperreactivity.

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29

Goncharov, Alexander, Elissaios Stavrou, Sergey Lobanov, Artem Oganov, Valery Roisen, Artem Chanyshev, Konstantin Litasov, Zuzana Konopkova, Kirill Zhuravlev, and Vitali Prakapenka. "Structure of methane and ethane at high pressure." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C757. http://dx.doi.org/10.1107/s2053273314092420.

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Methane is one of the most abundant hydrocarbon molecules in the universe and is expected to be a significant part of the icy giant planets (Uranus and Neptune) and their satellites. Ethane is one of the most predictable products of chemical reactivity of methane at extreme pressures and temperatures. In spite of numerous experimental and theoretical studies, the structure and relative stability of these materials even at room temperature remains controversial. We have performed a combined experimental and theoretical study of both methane and ethane up at high pressures up to 120 GPa at 300 K using x-ray diffraction and Raman spectroscopy and the ab-initio evolutionary algorithm, respectively. In the case of methane we have successfully solved the structure of phase B by determining the space group and the positional parameters of carbon atoms, and by completing these results for the hydrogen positions using the theoretical calculations. The general structural behavior under pressure and the relation between phase B and phases A and pre-B will be also discussed. For ethane we have determined the crystallization point, for room temperature, at 1.7 GPa and also the low pressure crystal structure (Phase A). This crystal structure is orientationally disordered (plastic phase) and deviates from the known crystal structures for ethane at low temperatures. Moreover, a pressure induced phase transition has been indentified, for the first time, at 18 GPa to a monoclinic phase III, the structure of which is solved based on a good agreement of the experimental results and theoretical predictions. We have determined the equations of state of methane and ethane, which provides a solid basis for the discussion of their relative stability at high pressures.

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30

Fares, Galal, and Abdulrahman M. Alhozaimy. "Assessment of Pozzolanic Activity of Ground Scoria Rocks under Low- and High-Pressure (Autoclave) Steam Curing." Materials 15, no. 13 (July 3, 2022): 4666. http://dx.doi.org/10.3390/ma15134666.

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Two sources of natural scoria rocks were procured and ground for use in concrete as natural pozzolans (NP1 and NP2). The evaluation of their pozzolanic reactivity is carried out using different techniques and approaches. The primary goal of employing these techniques is to monitor the amount of portlandite (CH=Ca(OH)2) consumed during steam curing at low or high pressure. The pozzolanicity of NP powders is determined either directly by monitoring CH variation or indirectly by compressive strength and microstructure development. Autoclave curing is known to stimulate the pozzolanicity of the inert siliceous and aluminosiliceous materials under its high-pressure steam conditions. Both steam-curing conditions were applied in this investigation. In this study, X-ray diffraction, scanning electron microscope, thermogravimetric, Fourier transform infrared, and isothermal analyzers were used. It is concluded that the nature and types of minerals in SR determine their pozzolanic reactivity as either low-pressure steam-reactive or high-pressure steam-reactive cementitious materials. Due to the nature of their silicate structures, notably single-chain or 3D-framework structures, plagioclase feldspars (albite-anorthite) minerals are high-pressure steam-reactive minerals, whereas pyroxene (enstatite and diopside) minerals are low-pressure steam-reactive minerals. Using high-pressure steam curing, varied replacement levels of up to 60% were achieved in NP1, with a consistent strength activity index (SAI) of 99%, while an SAI of 79% was obtained with NP2. During low-pressure steam curing, NP1 and NP2 consumed around 72 and 80% of portlandite, respectively, demonstrating their relative pozzolanic reactivity. When compared to the control concrete mix, the strength activity indices of NP1, NP2, and class F fly ash in their normal concrete mixes reached 74.3, 82, and 73.7%, respectively, after 56 days of normal curing conditions.

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31

Shalaby, Adel, Marwa Al-Gholam, Safa Elfiky, and Ghada Elgarawany. "Impact of High Aspartame and High Fructose Diet on Vascular Reactivity, Glucose Metabolism and Liver Structure in Diabetic Rats." Open Access Macedonian Journal of Medical Sciences 10, A (May 23, 2022): 1433–43. http://dx.doi.org/10.3889/oamjms.2022.8810.

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BACKGROUND: Diabetes mellitus is a chronic metabolic disorder, affected by fructose, and artificial sweeteners. Aspartame and fructose are popularly used, by diabetics, as substitutes to glucose. AIM: This study evaluated the effect of high aspartame and fructose on vascular reactivity, glucose, and hepatic metabolism in diabetic rats. MATERIALS AND METHODS: Forty-eight male rats were divided into six groups: Control, control-diabetic, aspartame, aspartame-diabetic, fructose, and fructose-diabetic. After 60 days, blood pressure, vascular reactivity to norepinephrine, Lipid profile, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), leptin, and Malondialdehyde (MDA) were measured. RESULTS: High aspartame alone or with diabetes, decreased leptin, vascular reactivity, and increased triglyceride, cholesterol, MDA, and fasting blood glucose. Hepatic tissues showed dilated congested vessels, cellular infiltration, decreased Periodic Acid Schiff’s reaction, and increased collagenous fibers. High fructose decreased leptin, high-density lipoprotein, vascular reactivity, and increased cholesterol, Low-density lipoprotein, MDA, glucose, and HOMA-IR. Hepatic tissues showed more fatty infiltration, glycogen deposition, and increased collagenous-fibers. The condition became worse in diabetes-treated rats. CONCLUSION: High aspartame and high fructose diet caused deleterious effects on diabetic rats by atherogenic, oxidative stress, vascular, glucose, and hepatic tissue metabolism impairment.

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Kumbhar, V. S., A. S. Shahare, and G. K. Awari. "Influence of injection pressure on performance and emission characteristics of single cylinder RCCI engine fuelled with ethanol gasoline and diesel biodiesel blends." Journal of Physics: Conference Series 2070, no. 1 (November 1, 2021): 012160. http://dx.doi.org/10.1088/1742-6596/2070/1/012160.

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Abstract Reactivity controlled compression ignition (RCCI) has great potential for a simultaneous reduction in Nitrogen oxides (NOx) and particulate matter (PM) with increase in thermal efficiency. In this experimentation, an attempt is made to investigate the effect of injection pressure on the performance emission and combustion characteristics of single cylinder RCCI engine. Literature reveals that injection pressure has a great influence on the quality of charge preparation, fuel stratification, and incylinder reactivity. Suitably modified engine was operated for 0 to 12 kg loads, for 400 to 700 injection pressure. The blend of ethanol gasoline E20 used as a low reactivity fuel and blend of diesel jatropha biodiesel B20 used as a high reactivity fuel. Experimental results showed that increase in injection pressure enhances the degree of charge homogeneity, reduces the combustion duration, and provides higher rate of energy release. For 12 kg load and 700 bar injection pressure, it is observed that 5% rise in thermal efficiency, 27% reduction in smoke opacity, 2% reduction in HC, 4% reduction in CO and 20% rise in NOx as compared to 400 bar injection pressure.

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33

Chen, Kefei, Yuanju Li, Chen Zhang, Shixin Zhou, Jing Li, Pengpeng Li, Zexiang Sun, Bingkun Meng, and Deliang Fu. "Experimental study of the hydrothermal reactivity of oxalic acid under high pressure." IOP Conference Series: Earth and Environmental Science 600, no. 1 (November 1, 2020): 012003. http://dx.doi.org/10.1088/1755-1315/600/1/012003.

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Abstract The thermal stability of organic acids has a close relationship with the formation mechanism of secondary pores in deep reservoirs. Experiments were conducted to investigate the thermal stability of oxalic acid under high pressure and the influence of K-feldspar on oxalic acid decomposition. The experiment temperatures were set in the range of 130-330°C and each experiment was performed for 72h under 60MPa. Results show that both temperature and K-feldspar have significant influence on the decomposition of oxalic acid. The oxalic acid decomposed slowly at temperatures less than 180°C, and most of the oxalic acid decomposed at temperatures between 180°C and 230°C. Besides, the decarboxylation reaction proceeded more slowly in the presence of K-feldspar than the mineral-free experiments, which is most likely attributed to the increasing pH caused by dissolution. In addition, because the decomposition rate of oxalic acid was low, the K-feldspar dissolution was not affected at temperatures lower than 230°C.

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34

Fauvel, J. P., I. MʼPio, P. Quelin, J. P. Rigaud, M. Laville, and M. Ducher. "NEITHER PERCEIVED JOB STRESS NOR INDIVIDUAL CARDIOVASCULAR REACTIVITY PREDICT HIGH BLOOD PRESSURE." Journal of Hypertension 22, Suppl. 2 (June 2004): S129—S130. http://dx.doi.org/10.1097/00004872-200406002-00452.

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35

Bukoski, R. D., and D. A. McCarron. "Altered aortic reactivity and lowered blood pressure associated with high calcium intake." American Journal of Physiology-Heart and Circulatory Physiology 251, no. 5 (November 1, 1986): H976—H983. http://dx.doi.org/10.1152/ajpheart.1986.251.5.h976.

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The hypothesis that dietary calcium (dCa) alters functional properties of aortic smooth muscle in the spontaneously hypertensive rat (SHR) was tested. At 6 wk of age, Wistar Kyoto (WKY) and (SHR) rats were placed on a control diet containing 1% Ca. The experimental SHR group received a 2%-calcium diet. After an average of either 8 or 15 wk on the diets (WOD), aortic rings were prepared for measurement of passive elastic properties and isometric force development. Differences in blood pressure (BP) were not apparent until after 8 WOD when the BP of SHRs on 2% dCa were 10-15 mmHg lower than SHRs on 1% dCa (P less than 0.05). After 8 WOD, when the BP effect first emerged, no significant differences in aortic properties were observed between the SHR groups. However, after 15 WOD, aortas of SHRs on 2% dCa were more compliant than those of SHRs on 1% dCa and between 8 and 15 WOD the sensitivity to KCl decreased in aortas from the WKY group and the SHRs on 2% dCa, but not the SHR-1% dCa group (mean effective dose went from 14.4 +/- 0.4 to 18.5 +/- 0.9 mM for WKY and from 13.6 +/- 0.6 to 17.1 +/- 1.2 mM for SHRs on 2% dCa, P less than 0.05). In addition, between 8 and 15 WOD, a significant decrease in response to a calcium (Ca2+) challenge after removal of K+ and Ca2+ occurred in aortas of the SHRs on 2% dCa, but not in the control diet groups, indicating that a decrease in aortic reactivity was present in the Ca2+-supplemented SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

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36

Ceppatelli, Matteo, Roberto Bini, and Vincenzo Schettino. "High-pressure reactivity of clathrate hydrates by two-photon dissociation of water." Phys. Chem. Chem. Phys. 13, no. 4 (2011): 1264–75. http://dx.doi.org/10.1039/c0cp01318h.

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37

Fauvel, Jean Pierre, Ignasse M’Pio, Pierre Quelin, Jean-Pierre Rigaud, Maurice Laville, and Michel Ducher. "Neither Perceived Job Stress Nor Individual Cardiovascular Reactivity Predict High Blood Pressure." Hypertension 42, no. 6 (December 2003): 1112–16. http://dx.doi.org/10.1161/01.hyp.0000102862.93418.ee.

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38

Fanetti, Samuele, Marcelo M. Nobrega, Kamil Dziubek, Margherita Citroni, Andrea Sella, Paul F. McMillan, Michael Hanfland, and Roberto Bini. "Structure and reactivity of 2,4,6-tricyano-1,3,5-triazine under high-pressure conditions." CrystEngComm 21, no. 30 (2019): 4493–500. http://dx.doi.org/10.1039/c8ce02154f.

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39

Ceppatelli, Matteo, Mario Santoro, Robert Bini, and Vincenzo Schettino. "High pressure reactivity of solid furan probed by infrared and Raman spectroscopy." Journal of Chemical Physics 118, no. 3 (January 15, 2003): 1499–506. http://dx.doi.org/10.1063/1.1527895.

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40

Ceppatelli, Matteo, Luca Fontana, and Margherita Citroni. "The high pressure reactivity of substituted acetylenes: a vibrational study on diphenylacetylene." Phase Transitions 80, no. 10-12 (October 2007): 1085–101. http://dx.doi.org/10.1080/01411590701473168.

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41

Hong, Seong-Hyeon, Jin-Ho Kim, and Myoung Youp Song. "Study on the reactivity of MgH2+MgB2 composites under high hydrogen pressure and high temperature." Materials Research Bulletin 48, no. 3 (March 2013): 1071–75. http://dx.doi.org/10.1016/j.materresbull.2012.11.109.

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42

Pires, J. G. P., A. M. Cabral, E. C. Vasquez, and N. S. Bissoli. "Effect of High Ethanol Intake on Vascular Reactivity to Serotonin, Vasopressin and Acetylcholine in Normotensive Rats." Journal of International Medical Research 21, no. 3 (May 1993): 133–37. http://dx.doi.org/10.1177/030006059302100303.

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Chronic ethanol administration causes hypertension and alterations of vascular reactivity in rats. In several models of hypertension, alterations of vascular reactivity are believed to be secondary to the sustained increase in blood pressure. The present study investigated the effects of serotonin (5-hydroxytryptamine [5-HT]), vasopressin and acetylcholine (ACh) in the isolated perfused mesenteric arteries from Wistar rats submitted to an 8-week course of chronic ethanol intake (8 g/kg day). No significant differences were observed in the dose – response curves with regard to: pressor effect of 0.04 — 10.0 nmole 5-HT; relaxant effect of 0.05 — 50.0 nmole ACh; or the pressor effects of two 1.5-nmole doses of vasopressin between control rats and ethanol-fed rats. These results suggest that modifications in arterial reactivity to endogenous vasoactive substances (observed in other studies involving more prolonged ethanol treatment in rats) may be, in part, secondary to the increase in blood pressure.

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43

Freed, A. N., U. A. Scheffel, L. J. Kelly, B. Bromberger-Barnea, and H. A. Menkes. "Perfusion of lung periphery: effects of local exposures to ozone and pressure." Journal of Applied Physiology 61, no. 2 (August 1, 1986): 640–46. http://dx.doi.org/10.1152/jappl.1986.61.2.640.

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Following ozone (O3) exposure, airways reactivity increases. We investigated the possibility that exposure to O3 causes a decrease in pulmonary perfusion, and that this decrease is associated with the increase in reactivity. Perfusion was measured with radiolabeled microspheres. A wedged bronchoscope was used to isolate sublobar segments in the middle and lower lobes of anesthetized dogs. Isolated segments were exposed to either O3 or an elevated alveolar pressure. Although increased alveolar pressure decreased microsphere density, exposure to 1 ppm O3 did not. Collateral system resistance rose significantly following exposure to O3 and to high pressure. These studies do not support the hypothesis that pulmonary perfusion is decreased following O3 exposure and is associated with subsequent increases in reactivity.

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44

Da Silva, Rita de Cássia Vilhena A. F., Priscila de Souza, and José Eduardo da Silva-Santos. "Increased diuresis, renal vascular reactivity, and blood pressure levels in young rats fed high sodium, moderately high fructose, or their association: a comparative evaluation." Applied Physiology, Nutrition, and Metabolism 41, no. 12 (December 2016): 1233–39. http://dx.doi.org/10.1139/apnm-2016-0283.

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Excessive intakes of sodium or fructose have been described as risk factors for hypertension. We hypothesized that even a moderately high fructose diet (6% fructose), either alone or in combination with high sodium (4% NaCl), may impair diuresis and renal and systemic vascular reactivity, contributing to the onset of high blood pressure in rats. Male Wistar rats were fed chow containing 4% NaCl (HS), 6% fructose (MHF), or both 4% NaCl and 6% fructose (HSMHF) for 6 weeks and had their diuresis, plasma creatinine, vascular reactivity of perfused kidneys and systemic arterial pressure evaluated. We found no differences in augmented diuresis among animals given HS, MHF, or HSMHF diets. After 6 weeks both the HS and HSMHF groups had increased weight in their left kidneys, but only the HSMHF group showed augmented plasma creatinine. The effects of phenylephrine on renal vascular perfusion pressure were similarly enhanced in kidneys from the HS, MHF, and HSMHF groups, but not on the systemic arterial pressure. Although when evaluated in anesthetized rats, only the HSMHF group presented augmented blood pressure, evaluation in conscious animals revealed that both the MHF and HSMHF diets, but not the HS alone, were able to induce tachycardia and hypertension. In conclusion, a MHF diet containing 6% fructose was enough to render the renal vascular bed hyperreactive to phenylephrine and to induce both hypertension and tachycardia. The combination of 6% fructose with 4% NaCl led to plasma accumulation of creatinine and accelerated the development of tachycardia.

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45

Leversee, River A., Kristen Rode, Eran Greenberg, Vitali B. Prakapenka, Jesse S. Smith, Martin Kunz, Chris J. Pickard, and Elissaios Stavrou. "High pressure chemical reactivity and structural study of the Na–P and Li–P systems." Journal of Materials Chemistry A 8, no. 41 (2020): 21797–803. http://dx.doi.org/10.1039/d0ta08563d.

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46

Gil, Stanisław, and Adam Smoliński. "Experimental Study of Hydrogasification of Lignite and Subbituminous Coal Chars." Scientific World Journal 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/867030.

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The experimental facility for pressure hydrogasification research was adapted to the pressure of 10 MPa and temperature of 1300 K, which ensured repeatability of results and hydrogen heating to the process temperature. A hydrogasification reaction of chars produced from two rank coals was investigated at temperatures up to 1173 K, pressures up to 8 MPa, and the gas flow rates of 0.5–5 dmn3/min. Reactivity of the “Szczerców” lignite char was found to be slightly higher than that of the subbituminous “Janina” coal char produced under the same conditions. A high value of the char reactivity was observed to a certain carbon conversion degree, above which a sharp drop took place. It was shown that, to achieve proper carbon conversion, the hydrogasification reaction must proceed at a temperature above 1200 K.

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47

Si, Xiaochen, R. Clinton Webb, and Joyce M. Richey. "Bezafibrate, an anti-hypertriglyceridemic drug, attenuates vascular hyperresponsiveness and elevated blood pressure in fructose-induced hypertensive rats." Canadian Journal of Physiology and Pharmacology 77, no. 10 (October 15, 1999): 755–62. http://dx.doi.org/10.1139/y99-061.

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A high fructose diet induces hypertension, hyperinsulinemia - insulin resistance, and hypertriglyceridemia (syndrome X). In this study, we investigated the role of an abnormal lipid profile in mediating fructose-induced hypertension. We hypothesized that bezafibrate, a lipid-lowering drug, would reduce elevated blood pressure and inhibit increased vascular reactivity in fructose-fed rats. Male rats were placed on four different diets: group 1 was fed standard chow (n = 6); group 2 was fed 60% fructose (n = 5); group 3 was fed fructose plus bezafibrate (30 mg·kg-1·day-1; drinking water; n = 5); and group 4 was fed standard chow plus bezafibrate (n = 6). In addition, the direct effects of very low density lipoprotein (VLDL) on vascular reactivity were examined. Bezafibrate treatment lowered blood pressure, free fatty acids, and triglycerides in the fructose-fed group, suggesting that lipid abnormalities play a role in the elevation of blood pressure in the fructose-induced hypertensive rat. Aortae from fructose-fed rats were hyperresponsive to the calcium channel agonist Bay K 8644, which was normalized with bezafibrate treatment. Incubation of aortae in a VLDL medium resulted in increased responsiveness to Bay K 8644, lending further support to lipid abnormalities altering vascular reactivity. An altered lipid profile evidenced by elevated triglycerides and free fatty acids is causally related to the development of high blood pressure and increased vascular reactivity in the fructose-induced hypertensive rat.Key words: Sprague-Dawley rats, hypertriglyceridemia, free fatty acids, vascular reactivity, aortae.

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48

Stern, N., M. Golub, M. Nyby, M. Berger, P. Eggena, D. B. Lee, M. L. Tuck, and A. S. Brickman. "Effect of high calcium intake on pressor responsivity in hypertensive rats." American Journal of Physiology-Heart and Circulatory Physiology 252, no. 6 (June 1, 1987): H1112—H1119. http://dx.doi.org/10.1152/ajpheart.1987.252.6.h1112.

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Some proposed mechanisms for the hypotensive effect of high calcium intake involve reduction in vascular responsivity. To assess the effect of dietary calcium on vascular responsivity, spontaneously hypertensive rats (SHR) were placed on normal (N-Ca; 0.4%) or high (H-Ca; 2.8%) casein-based synthetic diet for 4 wk. Intraarterial pressure, pressor response to graded intravenous infusion of norepinephrine (NE) and angiotensin II (ANG II), and in vitro vascular reactivity of tail artery segments to NE and transmural nerve stimulation (TNS) were studied. Urinary electrolyte excretion, plasma renin activity (PRA), aldosterone, NE, and epinephrine (EPI) were also determined. H-Ca SHR had a lower intraarterial systolic and diastolic pressure. However, H-Ca SHR had greater in vivo pressor response to both ANG II and NE. Maximal contractile force developed by tail artery segments in vitro in response to NE and TNS was slightly, but not significantly, higher in H-Ca SHR. In vitro dose-response curves to NE and TNS were not significantly different. Although H-Ca SHR had increased urinary excretion of sodium throughout the study period, PRA and aldosterone levels were similar in both groups. Plasma NE and EPI levels in the two groups were also not different. Despite lowered intra-arterial blood pressure, H-Ca SHR exhibited enhanced pressor response to ANG II and NE in vivo and a similar in vitro vascular reactivity to NE and TNS when compared with N-Ca SHR. Our results do not support a role for alterations in vascular reactivity to NE or ANG II in the hypotensive effect of high calcium intake in SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

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49

Rodriguez-Mateos, Ana, Akari Ishisaka, Kazuaki Mawatari, Alberto Vidal-Diez, Jeremy P. E. Spencer, and Junji Terao. "Blueberry intervention improves vascular reactivity and lowers blood pressure in high-fat-, high-cholesterol-fed rats." British Journal of Nutrition 109, no. 10 (October 9, 2012): 1746–54. http://dx.doi.org/10.1017/s0007114512003911.

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Growing evidence suggests that intake of flavonoid-containing foods may exert cardiovascular benefits in human subjects. We have investigated the effects of a 10-week blueberry (BB) supplementation on blood pressure (BP) and vascular reactivity in rats fed a high-fat/high-cholesterol diet, known to induce endothelial dysfunction. Rats were randomly assigned to follow a control chow diet, a chow diet supplemented with 2 % (w/w) BB, a high-fat diet (10 % lard; 0·5 % cholesterol) or the high fat plus BB for 10 weeks. Rats supplemented with BB showed significant reductions in systolic BP (SBP) of 11 and 14 %, at weeks 8 and 10, respectively, relative to rats fed the control chow diet (week 8 SBP: 107·5 (sem 4·7) v. 122·2 (sem 2·1) mmHg, P= 0·018; week 10 SBP: 115·0 (sem 3·1) v. 132·7 (sem 1·5) mmHg, P< 0·0001). Furthermore, SBP was reduced by 14 % in rats fed with the high fat plus 2 % BB diet at week 10, compared to those on the high-fat diet only (SBP: 118·2 (sem 3·6) v. 139·5 (sem 4·5) mmHg, P< 0·0001). Aortas harvested from BB-fed animals exhibited significantly reduced contractile responses (to l-phenylephrine) compared to those fed the control chow or high-fat diets. Furthermore, in rats fed with high fat supplemented with BB, aorta relaxation was significantly greater in response to acetylcholine compared to animals fed with the fat diet. These data suggest that BB consumption can lower BP and improve endothelial dysfunction induced by a high fat, high cholesterol containing diet.

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Austin, Anthony W., Michael R. Kushnick, Michael J. Knutson, Mark L. McGlynn, and Stephen M. Patterson. "Resting Plasma Lipids and Cardiovascular Reactivity to Acute Psychological Stress." Journal of Psychophysiology 29, no. 3 (July 1, 2015): 99–106. http://dx.doi.org/10.1027/0269-8803/a000140.

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Abstract. Prior research suggests that hyperlipidemia is associated with elevated blood pressure responses to acute stress but whether lipid levels influence underlying cardiac and vascular determinants of blood pressure during stress is not known. Thus, we examined whether lipids were associated with stress-induced blood pressure responses and responses of stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR). In 19 healthy university students (15 men), blood was drawn to measure lipid levels (triglycerides, low-density lipoprotein cholesterol [LDL-c], high-density lipoprotein cholesterol [HDL-c], total cholesterol) after a 10-min rest period. Participants then completed a 6-min mental arithmetic stressor and a 3-min cold pressor (separated by a 10-min recovery). This procedure was repeated twice, approximately 6 weeks apart. Lipids and hemodynamic values were averaged across the two sessions. Multiple linear regression analyses revealed that a model including LDL-c, HDL-c, and triglycerides significantly predicted diastolic blood pressure (DBP), R2adj = .45, p = .007, and systolic blood pressure (SBP) cold pressor reactivity, R2adj = .35, p = .023. Individually, only LDL-c significantly predicted DBP, β = .64, p = .003, and SBP cold pressor reactivity, β = .64, p = .005. The same model marginally predicted CO, R2adj = .24, p = .069, and TPR, R2adj = 21, p = .091, reactivity to mental arithmetic, but only triglycerides were independently associated with CO, β = −.63, p = .012, and TPR, β = .54, p = .029 reactivity. Lipids were not associated with heart rate (HR) or SV reactivity. LDL-c was positively associated with the blood pressure response to the cold pressor, whereas triglycerides were positively and negatively associated with the TPR and CO responses, respectively, to mental arithmetic. Endothelial dysfunction and greater release of vasoconstrictors in those with high lipids may explain these relationships.

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