1,306 research outputs found
Operation of a perfusive catalytic membrane with nonlinear kinetics
Operation of a perfusive catalytic curved membrane is systematized into different transport-reaction regimes. The internal viscous permeation improves the catalyst performance, measured here by the effectiveness factor and by its enhancement relative to purely diffusive conditions. A theoretical analysis is presented for nonlinear kinetic expressions, which are suitable to describe the consumption of a reactant in many (bio)catalytic systems. The kinetic and transport parameters required to attain maximum enhancement are related by simple design rules, which depend on the form of the reaction rate law (namely on the order of reaction and dimensionless inhibition constant). For zero-order reactions, these optimum conditions correspond to attaining negligible concentration at a position inside the membrane, while may be interpreted in general as separating situations of severe mass transfer resistance from cases of high effectiveness. It is important to incorporate the correct form of the kinetic expression in the analysis, so that the predictions can be used in a quantitative manner. The results for the different regimes are compiled in enhancement plots and in Peclet–Thiele diagrams. Moreover, the study also yielded new results for the nonlinear reaction–diffusion problem in a curved membrane with its two surfaces exposed to different concentrations, a case of relevance in membrane reactors
Noncommutative Geometry and Symplectic Field Theory
In this work we study representations of the Poincare group defined over
symplectic manifolds, deriving the Klein-Gordon and the Dirac equation in phase
space. The formalism is associated with relativistic Wigner functions; the
Noether theorem is derived in phase space and an interacting field, including a
gauge field, approach is discussed.Comment: To appear in Physics Letters
Regime mapping and the role of the intermediate region in wall-coated microreactors
Operation of a wall-coated microreactor can occur in several mass transfer-reaction regimes. We define these regimes analytically in several planes of a multi-parametric map, taking into account the different degrees of concentration profile development, as well as the influence of non-unity orders of reaction and reactant inhibition in the kinetic law. It was found that the regions where conversion can be calculated from simplified mass transfer models are not discriminated by common results for entrance-length. We also illustrate the trade-offs that exist across this operating map concerning the catalyst design (costs associated with loading and volume) and overall system performance (evaluated in terms of reactant conversion, flow efficiency and microreactor effectiveness). It is shown that under certain conditions, the existence of moderate mass transfer resistance can be advantageous (even if internal limitations cannot be avoided), clarifying the role of the intermediate transport-reaction region
Non-linear Liouville and Shr\"odinger equations in phase space
Unitary representations of the Galilei group are studied in phase space, in
order to describe classical and quantum systems. Conditions to write in general
form the generator of time translation and Lagrangians in phase space are then
established. In the classical case, Galilean invariance provides conditions for
writing the Liouville operator and Lagrangian for non-linear systems. We
analyze, as an example, a generalized kinetic equation where the collision term
is local and non-linear. The quantum counter-part of such unitary
representations are developed by using the Moyal (or star) product. Then a
non-linear Schr\"odinger equation in phase space is derived and analyzed. In
this case, an association with the Wigner formalism is established, which
provides a physical interpretation for the formalism
A quantum-like description of the planetary systems
The Titius-Bode law for planetary distances is reviewed. A model describing
the basic features of this rule in the "quantum-like" language of a wave
equation is proposed. Some considerations about the 't Hooft idea on the
quantum behaviour of deterministic systems with dissipation are discussed.Comment: LaTex file, 17 pages, no figures. Version published in Foundations of
Physics, August 200
Determining the density of states for classical statistical models: A random walk algorithm to produce a flat histogram
We describe an efficient Monte Carlo algorithm using a random walk in energy
space to obtain a very accurate estimate of the density of states for classical
statistical models. The density of states is modified at each step when the
energy level is visited to produce a flat histogram. By carefully controlling
the modification factor, we allow the density of states to converge to the true
value very quickly, even for large systems. This algorithm is especially useful
for complex systems with a rough landscape since all possible energy levels are
visited with the same probability. In this paper, we apply our algorithm to
both 1st and 2nd order phase transitions to demonstrate its efficiency and
accuracy. We obtained direct simulational estimates for the density of states
for two-dimensional ten-state Potts models on lattices up to
and Ising models on lattices up to . Applying this approach to
a 3D spin glass model we estimate the internal energy and entropy at
zero temperature; and, using a two-dimensional random walk in energy and
order-parameter space, we obtain the (rough) canonical distribution and energy
landscape in order-parameter space. Preliminary data suggest that the glass
transition temperature is about 1.2 and that better estimates can be obtained
with more extensive application of the method.Comment: 22 pages (figures included
Liver Proteomic Response To Hypertriglyceridemia In Human-apolipoprotein C-iii Transgenic Mice At Cellular And Mitochondrial Compartment Levels
Background: Hypertriglyceridemia (HTG) is defined as a triglyceride (TG) plasma level exceeding 150 mg/dl and is tightly associated with atherosclerosis, metabolic syndrome, obesity, diabetes and acute pancreatitis. The present study was undertaken to investigate the mitochondrial, sub-mitochondrial and cellular proteomic impact of hypertriglyceridemia in the hepatocytes of hypertriglyceridemic transgenic mice (overexpressing the human apolipoproteinC-III). Methods. Quantitative proteomics (2D-DIGE) analysis was carried out on both "low-expressor" (LE) and "high- expressor" (HE) mice, respectively exhibiting moderate and severe HTG, to characterize the effect of the TG plasma level on the proteomic response. Results: The mitoproteome analysis has revealed a large-scale phenomenon in transgenic mice, i.e. a general down-regulation of matricial proteins and up-regulation of inner membrane proteins. These data also demonstrate that the magnitude of proteomic changes strongly depends on the TG plasma level. Our different analyses indicate that, in HE mice, the capacity of several metabolic pathways is altered to promote the availability of acetyl-CoA, glycerol-3-phosphate, ATP and NADPH for TG de novo biosynthesis. The up-regulation of several cytosolic ROS detoxifying enzymes has also been observed, suggesting that the cytoplasm of HTG mice is subjected to oxidative stress. Moreover, our results suggest that iron over-accumulation takes place in the cytosol of HE mice hepatocytes and may contribute to enhance oxidative stress and to promote cellular proliferation. Conclusions: These results indicate that the metabolic response to HTG in human apolipoprotein C-III overexpressing mice may support a high TG production rate and that the cytosol of hepatocytes is subjected to an important oxidative stress, probably as a result of FFA over-accumulation, iron overload and enhanced activity of some ROS-producing catabolic enzymes. © 2014 Ehx et al.; licensee BioMed Central Ltd.131Grundy, S.M., Brewer Jr., H.B., Cleeman, J.I., Smith Jr., S.C., Lenfant, C., Definition of Metabolic Syndrome: Report of the National Heart, Lung, and Blood Institute/American Heart Association Conference on Scientific Issues Related to Definition (2004) Circulation, 109 (3), pp. 433-438. , DOI 10.1161/01.CIR.0000111245.75752.C6Reid, A.E., Nonalcoholic steatohepatitis (2001) Gastroenterology, 121 (3), pp. 710-723Toskes, P.P., Hyperlipidemic pancreatitis (1990) Gastroenterol Clin North Am, 19, pp. 783-791Ginsberg, H.N., Ngoc-Anh, L., Goldberg, I.J., Apolipoprotein B metabolism in subjects with deficiency of apolipoproteins CIII and AI. Evidence that apolipoprotein CIII inhibits catabolism of triglyceride-rich lipoproteins by lipoprotein lipase in vivo (1986) Journal of Clinical Investigation, 78 (5), pp. 1287-1295Maeda, N., Li, H., Lee, D., Oliver, P., Quarfordt, S.H., Osada, J., Targeted disruption of the apolipoprotein C-III gene in mice results in hypotriglyceridemia and protection from postprandial hypertriglyceridemia (1994) Journal of Biological Chemistry, 269 (38), pp. 23610-23616Shoulders, C.C., Harry, P.J., Lagrost, L., White, S.E., Shah, N.F., North, J.D., Gilligan, M., Ball, M.J., Variation at the apo AI/CIII/AIV gene complex is associated with elevated plasma levels of apo CIII (1991) Atherosclerosis, 87, pp. 239-247Jong, M.C., Rensen, P.C.N., Dahlmans, V.E.H., Van Der Boom, H., Van Berkel, T.J.C., Havekes, L.M., Apolipoprotein C-III deficiency accelerates triglyceride hydrolysis by lipoprotein lipase in wild-type and apoE knockout mice (2001) Journal of Lipid Research, 42 (10), pp. 1578-1585Wang, C.-S., McConathy, W., Kloer, H.U., Alaupovic, P., Modulation of lipoprotein lipase activity by apolipoproteins. Effect of apolipoprotein C-III (1985) Journal of Clinical Investigation, 75 (2), pp. 384-390Mann, C.J., Troussard, A.A., Yen, F.T., Hannouche, N., Najib, J., Fruchart, J.-C., Lotteau, V., Bihain, B.E., Inhibitory effects of specific apolipoprotein C-III isoforms on the binding of triglyceride-rich lipoproteins to the lipolysis-stimulated receptor (1997) Journal of Biological Chemistry, 272 (50), pp. 31348-31354. , DOI 10.1074/jbc.272.50.31348Windler, E., Havel, R.J., Inhibitory effects of C apolipoproteins from rats and humans on the uptake of triglyceride-rich lipoproteins and their remnants by the perfused rat liver (1985) Journal of Lipid Research, 26 (5), pp. 556-565Ito, Y., Azrolan, N., O'Connell, A., Walsh, A., Breslow, J.L., Hypertriglyceridemia as a result of human apo CIII gene expression in transgenic mice (1990) Science, 249, pp. 790-793Aalto-Setala, K., Fisher, E.A., Chen, X., Chajek-Shaul, T., Hayek, T., Zechner, R., Walsh, A., Breslow, J.L., Mechanism of hypertriglyceridemia in human apolipoprotein (apo) CIII transgenic mice. Diminished very low density lipoprotein fractional catabolic rate associated with increased apo CIII and reduced apo e on the particles (1992) J Clin Invest, 90, pp. 1889-1900Reaven, G.M., Mondon, C.E., Chen, Y.-D.I., Breslow, J.L., Hypertriglyceridemic mice transgenic for the human apolipoprotein C-III gene are neither insulin resistant nor hyperinsulinemic (1994) Journal of Lipid Research, 35 (5), pp. 820-824Alberici, L.C., Oliveira, H.C.F., Patricio, P.R., Kowaltowski, A.J., Vercesi, A.E., Hyperlipidemic Mice Present Enhanced Catabolism and Higher Mitochondrial ATP-Sensitive K+ Channel Activity (2006) Gastroenterology, 131 (4), pp. 1228-1234. , DOI 10.1053/j.gastro.2006.07.021, PII S0016508506016647Salerno, A.G., Silva, T.R., Amaral, M.E.C., Alberici, L.C., Bonfleur, M.L., Patricio, P.R., Francesconi, E.P.M.S., Oliveira, H.C.F., Overexpression of apolipoprotein CIII increases and CETP reverses diet-induced obesity in transgenic mice (2007) International Journal of Obesity, 31 (10), pp. 1586-1595. , DOI 10.1038/sj.ijo.0803646, PII 0803646Amaral, M.E.C., Oliveira, H.C.F., Carneiro, E.M., Delghingaro-Augusto, V., Vieira, E.C., Berti, J.A., Boschero, A.C., Plasma glucose regulation and insulin secretion in hypertriglyceridemic mice (2002) Hormone and Metabolic Research, 34 (1), pp. 21-26. , DOI 10.1055/s-2002-19962Alberici, L.C., Vercesi, A.E., Oliveira, H.C., Mitochondrial energy metabolism and redox responses to hypertriglyceridemia (2011) J Bioenerg Biomembr, 43, pp. 19-23Alberici, L.C., Oliveira, H.C.F., Bighetti, E.J.B., De Faria, E.C., Degaspari, G.R., Souza, C.T., Vercesi, A.E., Hypertriglyceridemia Increases Mitochondrial Resting Respiration and Susceptibility to Permeability Transition (2003) Journal of Bioenergetics and Biomembranes, 35 (5), pp. 451-457. , DOI 10.1023/A:1027343915452Garlid, K.D., Paucek, P., Mitochondrial potassium transport: The K(+) cycle (2003) Biochim Biophys Acta, 1606, pp. 23-41Alberici, L.C., Oliveira, H.C., Paim, B.A., Mantello, C.C., Augusto, A.C., Zecchin, K.G., Gurgueira, S.A., Vercesi, A.E., Mitochondrial ATP-sensitive K(+) channels as redox signals to liver mitochondria in response to hypertriglyceridemia (2009) Free Radic Biol Med, 47, pp. 1432-1439Mathy, G., Sluse, F.E., Mitochondrial comparative proteomics: Strengths and pitfalls (2008) Biochim Biophys Acta, 1777, pp. 1072-1077Douette, P., Navet, R., Gerkens, P., De Pauw, E., Leprince, P., Sluse-Goffart, C., Sluse, F.E., Steatosis-induced proteomic changes in liver mitochondria evidenced by two-dimensional differential in-gel electrophoresis (2005) Journal of Proteome Research, 4 (6), pp. 2024-2031. , DOI 10.1021/pr050187zMarouga, R., David, S., Hawkins, E., The development of the DIGE system: 2D fluorescence difference gel analysis technology (2005) Analytical and Bioanalytical Chemistry, 382 (3), pp. 669-678. , DOI 10.1007/s00216-005-3126-3Sue, G.R., Ho, Z.C., Kim, K., Peroxiredoxins: A historical overview and speculative preview of novel mechanisms and emerging concepts in cell signaling (2005) Free Radical Biology and Medicine, 38 (12), pp. 1543-1552. , DOI 10.1016/j.freeradbiomed.2005.02.026, PII S0891584905000985Hayes, J.D., Flanagan, J.U., Jowsey, I.R., Glutathione transferases (2005) Annual Review of Pharmacology and Toxicology, 45, pp. 51-88. , DOI 10.1146/annurev.pharmtox.45.120403.095857Raisanen, S.R., Lehenkari, P., Tasanen, M., Rahkila, P., Harkonen, P.L., Vaananen, H.K., Carbonic anhydrase III protects cells from hydrogen peroxide-induced apoptosis (1999) FASEB Journal, 13 (3), pp. 513-522Zheng, J., Li, Y., Yang, J., Liu, Q., Shi, M., Zhang, R., Shi, H., Liu, W., NDRG2 inhibits hepatocellular carcinoma adhesion, migration and invasion by regulating CD24 expression (2011) BMC Cancer, 11 (251), pp. 251-259Lee, H.Y., Birkenfeld, A.L., Jornayvaz, F.R., Jurczak, M.J., Kanda, S., Popov, V., Frederick, D.W., Shulman, G.I., Apolipoprotein CIII overexpressing mice are predisposed to diet-induced hepatic steatosis and hepatic insulin resistance (2011) Hepatology, 54, pp. 1650-1660Mathy, G., Navet, R., Gerkens, P., Leprince, P., De Pauw, E., Sluse-Goffart, C.M., Sluse, F.E., Douette, P., Saccharomyces cerevisiae mitoproteome plasticity in response to recombinant alternative ubiquinol oxidase (2006) Journal of Proteome Research, 5 (2), pp. 339-348. , DOI 10.1021/pr050346eKnowles, M.R., Cervino, S., Skynner, H.A., Hunt, S.P., De Felipe, C., Salim, K., Meneses-Lorente, G., Guest, P.C., Multiplex proteomic analysis by two-dimensional differential in-gel electrophoresis (2003) Proteomics, 3 (7), pp. 1162-1171. , DOI 10.1002/pmic.200300437Cardoso, A.R., Queliconi, B.B., Kowaltowski, A.J., Mitochondrial ion transport pathways: Role in metabolic diseases (2010) Biochim Biophys Acta, 1797, pp. 832-838Bonnard, C., Durand, A., Peyrol, S., Chanseaume, E., Chauvin, M.-A., Morio, B., Vidal, H., Rieusset, J., Mitochondrial dysfunction results from oxidative stress in the skeletal muscle of diet-induced insulin-resistant mice (2008) Journal of Clinical Investigation, 118 (2), pp. 789-800. , http://www.jci.org/articles/view/32601/pdf, DOI 10.1172/JCI32601Haynes, C.M., Fiorese, C.J., Lin, Y.F., Evaluating and responding to mitochondrial dysfunction: The mitochondrial unfolded-protein response and beyond (2013) Trends Cell Biol, 23, pp. 311-318MacGarvey, N.C., Suliman, H.B., Bartz, R.R., Fu, P., Withers, C.M., Welty-Wolf, K.E., Piantadosi, C.A., Activation of mitochondrial biogenesis by heme oxygenase-1-mediated NF-E2-related factor-2 induction rescues mice from lethal Staphylococcus aureus sepsis (2012) Am J Respir Crit Care Med, 185, pp. 851-861Piao, C.S., Gao, S., Lee, G.H., Kim Do, S., Park, B.H., Chae, S.W., Chae, H.J., Kim, S.H., Sulforaphane protects ischemic injury of hearts through antioxidant pathway and mitochondrial K(ATP) channels (2010) Pharmacol Res, 61, pp. 342-348Fodor, I.K., Nelson, D.O., Alegria-Hartman, M., Robbins, K., Langlois, R.G., Turteltaub, K.W., Corzett, T.H., McCutchen-Maloney, S.L., Statistical challenges in the analysis of two-dimensional difference gel electrophoresis experiments using DeCyder™ (2005) Bioinformatics, 21 (19), pp. 3733-3740. , DOI 10.1093/bioinformatics/bti612Callister, S.J., Barry, R.C., Adkins, J.N., Johnson, E.T., Qian, W.-J., Webb-Robertson, B.-J.M., Smith, R.D., Lipton, M.S., Normalization approaches for removing systematic biases associated with mass spectrometry and label-free proteomics (2006) Journal of Proteome Research, 5 (2), pp. 277-286. , DOI 10.1021/pr050300lNg, D.S., Xie, C., Maguire, G.F., Zhu, X., Ugwu, F., Lam, E., Connelly, P.W., Hypertriglyceridemia in Lecithin-cholesterol Acyltransferase-deficent Mice Is Associated with Hepatic Overproduction of Triglycerides, Increased Lipogenesis, and Improved Glucose Tolerance (2004) Journal of Biological Chemistry, 279 (9), pp. 7636-7642. , DOI 10.1074/jbc.M309439200Li, L.O., Hu, Y.F., Wang, L., Mitchell, M., Berger, A., Coleman, R.A., Early hepatic insulin resistance in mice: A metabolomics analysis (2010) Mol Endocrinol, 24, pp. 657-666Thomas, A., Stevens, A.P., Klein, M.S., Hellerbrand, C., Dettmer, K., Gronwald, W., Oefner, P.J., Reinders, J., Early changes in the liver-soluble proteome from mice fed a nonalcoholic steatohepatitis inducing diet (2012) Proteomics, 12, pp. 1437-1451Ray, P.D., Huang, B.W., Tsuji, Y., Reactive oxygen species (ROS) homeostasis and redox regulation in cellular signaling (2012) Cell Signal, 24, pp. 981-990Dansen, T.B., Wirtz, K.W.A., The peroxisome in oxidative stress (2001) IUBMB Life, 51 (4), pp. 223-230. , DOI 10.1080/152165401753311762Leclercq, I.A., Farrell, G.C., Field, J., Bell, D.R., Gonzalez, F.J., Robertson, G.R., CYP2E1 and CYP4A as microsomal catalysts of lipid peroxides in murine nonalcoholic steatohepatitis (2000) Journal of Clinical Investigation, 105 (8), pp. 1067-1075Zhang, Y.K., Wu, K.C., Klaassen, C.D., Genetic activation of Nrf2 protects against fasting-induced oxidative stress in livers of mice (2013) PLoS One, 8, p. 559122Mackenzie, E.L., Iwasaki, K., Tsuji, Y., Intracellular iron transport and storage: From molecular mechanisms to health implications (2008) Antioxidants and Redox Signaling, 10 (6), pp. 997-1030. , DOI 10.1089/ars.2007.1893Dongiovanni, P., Fracanzani, A.L., Fargion, S., Valenti, L., Iron in fatty liver and in the metabolic syndrome: A promising therapeutic target (2011) J Hepatol, 55, pp. 920-932Rouault, T.A., Hentze, M.W., Caughman, S.W., Harford, J.B., Klausner, R.D., Binding of a cytosolic protein to the iron-responsive element of human ferritin messenger RNA (1988) Science, 241, pp. 1207-1210Hentze, M.W., Caughman, S.W., Rouault, T.A., Barriocanal, J.G., Dancis, A., Harford, J.B., Klausner, R.D., Identification of the iron responsive element for the translational regulation of human ferritin mRNA (1987) Science, 238 (4833), pp. 1570-1573Petrak, J., Myslivcova, D., Man, P., Cmejla, R., Cmejlova, J., Vyoral, D., Elleder, M., Vulpe, C.D., Proteomic analysis of hepatic iron overload in mice suggests dysregulation of urea cycle, impairment of fatty acid oxidation, and changes in the methylation cycle (2007) Am J Physiol Gastrointest Liver Physiol, 292, pp. 71490-G1498Krawczyk, M., Bonfrate, L., Portincasa, P., Nonalcoholic fatty liver disease (2010) Best Pract Res Clin Gastroenterol, 24, pp. 695-708Koek, G.H., Liedorp, P.R., Bast, A., The role of oxidative stress in non-alcoholic steatohepatitis (2011) Clin Chim Acta, 412, pp. 1297-1305Caldwell, S.H., De Freitas, L.A., Park, S.H., Moreno, M.L., Redick, J.A., Davis, C.A., Sisson, B.J., Al-Osaimi, A., Intramitochondrial crystalline inclusions in nonalcoholic steatohepatitis (2009) Hepatology, 49, pp. 1888-1895Sickmann, A., Reinders, J., Wagner, Y., Joppich, C., Zahedi, R., Meyer, H.E., Schonfisch, B., Meisinger, C., The proteome of Saccharomyces cerevisiae mitochondria (2003) Proceedings of the National Academy of Sciences of the United States of America, 100 (23), pp. 13207-13212. , DOI 10.1073/pnas.2135385100Sottocasa, G.L., Kuylenstierna, B., Ernster, L., Bergstrand, A., An electron-transport system associated with the outer membrane of liver mitochondria. A biochemical and morphological study (1967) J Cell Biol, 32, pp. 415-438Hurkman, W.J., Tanaka, C.K., Solubilization of plant membrane proteins for analysis by two-dimensional gel electrophoresis (1986) Plant Physiol, 81, pp. 802-806Shevchenko, An., Wilm, M., Vorm, O., Jensen, O.N., Podtelejnikov, A.V., Neubauer, G., Shevchenko, Al., Mann, M., A strategy for identifying gel-separated proteins in sequence databases by MS alone (1996) Biochemical Society Transactions, 24 (3), pp. 893-89
Conformally flat spacetimes and Weyl frames
We discuss the concepts of Weyl and Riemann frames in the context of metric
theories of gravity and state the fact that they are completely equivalent as
far as geodesic motion is concerned. We apply this result to conformally flat
spacetimes and show that a new picture arises when a Riemannian spacetime is
taken by means of geometrical gauge transformations into a Minkowskian flat
spacetime. We find out that in the Weyl frame gravity is described by a scalar
field. We give some examples of how conformally flat spacetime configurations
look when viewed from the standpoint of a Weyl frame. We show that in the
non-relativistic and weak field regime the Weyl scalar field may be identified
with the Newtonian gravitational potential. We suggest an equation for the
scalar field by varying the Einstein-Hilbert action restricted to the class of
conformally-flat spacetimes. We revisit Einstein and Fokker's interpretation of
Nordstr\"om scalar gravity theory and draw an analogy between this approach and
the Weyl gauge formalism. We briefly take a look at two-dimensional gravity as
viewed in the Weyl frame and address the question of quantizing a conformally
flat spacetime by going to the Weyl frame.Comment: LATEX - 18 page
Measuring CMB Polarization with BOOMERANG
BOOMERANG is a balloon-borne telescope designed for long duration (LDB)
flights around Antarctica. The second LDB Flight of BOOMERANG took place in
January 2003. The primary goal of this flight was to measure the polarization
of the CMB. The receiver uses polarization sensitive bolometers at 145 GHz.
Polarizing grids provide polarization sensitivity at 245 and 345 GHz. We
describe the BOOMERANG telescope noting changes made for 2003 LDB flight, and
discuss some of the issues involved in the measurement of polarization with
bolometers. Lastly, we report on the 2003 flight and provide an estimate of the
expected results.Comment: 12 pages, 8 figures, To be published in the proceedings of "The
Cosmic Microwave Background and its Polarization", New Astronomy Reviews,
(eds. S. Hanany and K.A. Olive). Fixed typos, and reformatted citation
- …