Academic literature on the topic 'Substrate exchange kinetics'
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Journal articles on the topic "Substrate exchange kinetics"
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Stein, Allan R. "The ion-pair mechanism and bimolecular displacement at saturated carbon. VI. Racemization and radio-bromide exchange for substituted 1-phenylbromoethanes; solvent effects." Canadian Journal of Chemistry 65, no. 2 (February 1, 1987): 363–71. http://dx.doi.org/10.1139/v87-062.
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Racemization and radio-bromide exchange kinetics for 1-phenylbromoethanes in acetonitrile and in nitromethane using tetrabutylammonium bromide are reported. The results, together with those previously reported for acetone solutions, provide direct empirical support for the ion-pair mechanism for nucleophilic substitution at saturated carbon. Changing the substituents on the phenyl from the 4-nitro through to the 3,4-dimethyl substrate and the solvent from acetone to the more polar acetonitrile and nitromethane shifts the transition state for bromide substitution from an early to a late stage of the equilibria series substrate [Formula: see text] intimate ion pair [Formula: see text] various solvated ion pairs [Formula: see text] free or dissociated ions. For all the substrates in acetone and, for the species giving the less stable carbocations, in acetonitrile and nitromethane, both racemizations and exchanges are bimolecular. In the latter solvents, the substrates giving the more stable carbocations show mixed kinetics.
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Hasenhuetl, Peter S., Shreyas Bhat, Felix P. Mayer, Harald H. Sitte, Michael Freissmuth, and Walter Sandtner. "A kinetic account for amphetamine-induced monoamine release." Journal of General Physiology 150, no. 3 (February 9, 2018): 431–51. http://dx.doi.org/10.1085/jgp.201711915.
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The plasmalemmal monoamine transporters for dopamine, norepinephrine, and serotonin (SERT) are targets for amphetamines. In vivo, amphetamines elicit most, if not all, of their actions by triggering monoamine efflux. This is thought to be accomplished by an amphetamine-induced switch from the forward-transport to the substrate-exchange mode. The mechanism underlying this switch has remained elusive; available kinetic models posit that substrates and cosubstrate Na+ ions bind either in a random or in a sequential order. Neither can account for all reported experimental observations. We used electrophysiological recordings to interrogate crucial conformational transitions associated with the binding of five different substrates (serotonin, para-chloroamphetamine, and the high-affinity naphthyl-propan-amines PAL-287, PAL-1045, and PAL-1046) to human SERT expressed in HEK293 cells; specifically, we determined the relaxation kinetics of SERT from a substrate-loaded to a substrate-free state at various intracellular and extracellular Na+ concentrations. These rates and their dependence on intracellular and extracellular Na+ concentrations differed considerably between substrates. We also examined the effect of K+ on substrate affinity and found that K+ enhanced substrate dissociation. A kinetic model was developed, which allowed for random, but cooperative, binding of substrate and Na+ (or K+). The synthetic data generated by this model recapitulated the experimental observations. More importantly, the cooperative binding model accounted for the releasing action of amphetamines without any digression from alternating access. To the best of our knowledge, this model is the first to provide a mechanistic framework for amphetamine-induced monoamine release and to account for the findings that some substrates are less efficacious than others in promoting the substrate-exchange mode.
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Restrepo, D., D. J. Kozody, L. J. Spinelli, and P. A. Knauf. "Cl-Cl exchange in promyelocytic HL-60 cells follows simultaneous rather than ping-pong kinetics." American Journal of Physiology-Cell Physiology 257, no. 3 (September 1, 1989): C520—C527. http://dx.doi.org/10.1152/ajpcell.1989.257.3.c520.
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The intra- and extracellular chloride concentration dependencies of the rate of Cl-Cl exchange in human promyelocytic leukemic HL-60 cells were studied by means of radioactive isotope (36Cl) efflux measurements. Efflux of isotope from cells follows an exponential time course. The Cl-Cl exchange flux follows Michaelis-Menten kinetics as a function of both intra- and extracellular chloride concentrations. The ratio of the maximum exchange velocity to the apparent Michaelis constant for both extracellular and intracellular substrate increases as a function of trans Cl concentration, indicating that Cl-Cl exchange in the HL-60 cell does not follow ping-pong kinetics. A kinetic scheme in which extracellular and intracellular chloride ions bind in random order to the transporter and are then translocated simultaneously can adequately model the experimental data.
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Kosa, Nicolas M., Kevin M. Pham, and Michael D. Burkart. "Chemoenzymatic exchange of phosphopantetheine on protein and peptide." Chem. Sci. 5, no. 3 (2014): 1179–86. http://dx.doi.org/10.1039/c3sc53154f.
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Deshmukh, Lalit, Vitali Tugarinov, John M. Louis, and G. Marius Clore. "Binding kinetics and substrate selectivity in HIV-1 protease−Gag interactions probed at atomic resolution by chemical exchange NMR." Proceedings of the National Academy of Sciences 114, no. 46 (October 30, 2017): E9855—E9862. http://dx.doi.org/10.1073/pnas.1716098114.
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The conversion of immature noninfectious HIV-1 particles to infectious virions is dependent upon the sequential cleavage of the precursor group-specific antigen (Gag) polyprotein by HIV-1 protease. The precise mechanism whereby protease recognizes distinct Gag cleavage sites, located in the intrinsically disordered linkers connecting the globular domains of Gag, remains unclear. Here, we probe the dynamics of the interaction of large fragments of Gag and various variants of protease (including a drug resistant construct) using Carr−Purcell−Meiboom−Gill relaxation dispersion and chemical exchange saturation transfer NMR experiments. We show that the conformational dynamics within the flaps of HIV-1 protease that form the lid over the catalytic cleft play a significant role in substrate specificity and ordered Gag processing. Rapid interconversion between closed and open protease flap conformations facilitates the formation of a transient, sparsely populated productive complex between protease and Gag substrates. Flap closure traps the Gag cleavage sites within the catalytic cleft of protease. Modulation of flap opening through protease−Gag interactions fine-tunes the lifetime of the productive complex and hence the likelihood of Gag proteolysis. A productive complex can also be formed in the presence of a noncognate substrate but is short-lived owing to lack of optimal complementarity between the active site cleft of protease and the substrate, resulting in rapid flap opening and substrate release, thereby allowing protease to differentiate between cognate and noncognate substrates.
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Oldfield, C. "Evaluation of steady-state kinetic parameters for enzymes solubilized in water-in-oil microemulsion systems." Biochemical Journal 272, no. 1 (November 15, 1990): 15–22. http://dx.doi.org/10.1042/bj2720015.
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1. Equations are derived for the steady-state kinetics of substrate conversion by enzymes confined within the water-droplets of water-in-oil microemulsion systems. 2. Water-soluble substrates initially confined within droplets that do not contain enzyme are assumed to be converted into product only after they enter enzyme-containing droplets via the inter-droplet exchange process. 3. Hyperbolic (Michaelis-Menten) kinetics are predicted when the substrate concentration is varied in microemulsions of fixed composition. Both kcat. and Km are predicted to be dependent on the size and concentration of the water-droplets in the microemulsion. 4. The predicted behaviour is shown to be supported by published experimental data. A physical interpretation of the form of the rate equation is presented. 5. The rate equation for an oil-soluble substrate was derived assuming a pseudo-two-phase (oil & water) model for the microemulsion. Both kcat. and Km are shown to be independent of phi aq. Km is larger than the aqueous solution value by a factor approximately equal to the oil/water partition coefficient of the substrate. The validity of the rate equation is confirmed by published data.
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Goward, C. R., R. Hartwell, T. Atkinson, and M. D. Scawen. "The purification and characterization of glucokinase from the thermophile Bacillus stearothermophilus." Biochemical Journal 237, no. 2 (July 15, 1986): 415–20. http://dx.doi.org/10.1042/bj2370415.
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Homogeneous glucokinase (EC 2.7.1.2) from the thermophile Bacillus stearothermophilus was isolated on the large scale by using four major steps: precipitation of extraneous material at pH 5.5, ion-exchange chromatography on DEAE-Sepharose, pseudo-affinity chromatography on Procion Brown H-3R-Sepharose 4B and gel filtration on Ultrogel AcA 34. The purified enzyme had a specific activity of about 330 units/mg of protein and was shown to exist as a dimer of subunit Mr 33,000. Kinetic parameters for the enzyme were determined with a variety of substrates. The glucokinase was highly specific for alpha-D-glucose, and the only other sugar substrate utilized was N-acetyl-alpha-D-glucosamine. The enzyme shows Michaelis-Menten kinetics, with a Km value of 150 microM for alpha-D-glucose. The glucokinase was maximally active at pH 9.0.
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Knickelbein, R. G., P. S. Aronson, and J. W. Dobbins. "Characterization of Na(+)-H+ exchangers on villus cells in rabbit ileum." American Journal of Physiology-Gastrointestinal and Liver Physiology 259, no. 5 (November 1, 1990): G802—G806. http://dx.doi.org/10.1152/ajpgi.1990.259.5.g802.
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The presence of Na(+)-H+ exchange activity is demonstrated on both the brush-border membrane (BBM) and the basolateral membrane (BLM) of villus cells from rabbit ileum. The possibility that the Na(+)-H+ exchange activity on the BLM represents HCO3- cotransport is excluded. The two Na(+)-H+ exchangers are then compared in terms of kinetics and substrate and inhibitor specificity. The most striking difference between the two exchangers was sensitivity to amiloride and K+. The IC50 for amiloride on the BLM was 10-fold lower than the BBM (11.2 +/- 2.1 vs. 103 +/- 20.9 microM; P less than 0.02). External K+, in concentrations as low as 10 mM, inhibited Na(+)-H+ exchange on the BBM but not on the BLM. The Na+ Km and proton Km were twice as high on the BLM exchanger (46.3 +/- 3.4 vs. 28.8 +/- 2.3 mM and 468 +/- 9 vs. 232 +/- 45 nM, respectively). Proton Vmax was similar, whereas Na+ Vmax was higher on the BLM. Inhibition by Li+ was similar on both membranes. These results indicate distinct differences between the two Na(+)-H+ exchangers. Whether these differences are due to the two different gene products or are the result of posttranslational modification of a single gene product remains to be determined.
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Krupka, R. M. "Testing transport models and transport data by means of kinetic rejection criteria." Biochemical Journal 260, no. 3 (June 15, 1989): 885–91. http://dx.doi.org/10.1042/bj2600885.
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In the case of a transport system obeying Michaelis-Menten kinetics, completely general relationships are shown to exist between the final ratio of internal and external substrate concentrations, alpha, and the V/Km ratios found in zero-trans-entry, zero-trans-exit and equilibrium-exchange experiments (where V is a maximum substrate flux and Km a substrate half-saturation constant). The proof depends on a new method of derivation proceeding from the form of the experimental data rather than, as has been the practice in kinetic analysis, from a hypothetical reaction scheme. These general relationships, which will be true of all mechanisms giving rise to a particular type of behaviour (here Michaelis-Menten kinetics), provide a test for internal consistency in a set of experimental data. Other relationships, which are specific, can be derived from individual reaction schemes, with the use of traditional procedures in kinetic analysis. The specific relationships include constants for infinite trans entry and exit in addition to constants involved in the general relationships. In conjunction, the general and specific relationships provide a stringent test of mechanism. A set of results that fails to satisfy the general relationships must be rejected; here systematic error or unexpected changes in the transport system in different experiments may have distorted the calculated constants, or the system may not actually obey Michaelis-Menten kinetics. Results in accord with the general relationships, on the other hand, can be applied in specific tests of mechanism. The usefulness of the theorem is illustrated in the cases of the glucose-transport and choline-transport systems of erythrocytes. Experimental results taken from several studies in the literature, which were in accord with hyperbolic substrate kinetics, had previously been shown to disagree with relationships derived for the carrier model, and the model was rejected. The new analysis shows that the data violated the general relationships and therefore cannot decide the issue. More recent results on the glucose-transport system satisfy the general relations and agree with the carrier model.
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PAOLI, Paolo, Paolo CIRRI, Lucia CAMICI, Giampaolo MANAO, Gianni CAPPUGI, Gloriano MONETI, Giuseppe PIERACCINI, Guido CAMICI, and Giampietro RAMPONI. "Common-type acylphosphatase: steady-state kinetics and leaving-group dependence." Biochemical Journal 327, no. 1 (October 1, 1997): 177–84. http://dx.doi.org/10.1042/bj3270177.
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A number of acyl phosphates differing in the structure of the acyl moiety (as well as in the leaving-group pKa of the acids produced in hydrolysis) have been synthesized. The Km and Vmax values for the bovine common-type acylphosphatase isoenzyme have been measured at 25 °C and pH 5.3. The values of kcat differ widely in relation to the different structures of the tested acyl phosphates: linear relationships between log kcat and the leaving group pKa, as well as between log kcat/Km and the leaving-group pKa, were observed. On the other hand, the Km values of the different substrates are very close to each other, suggesting that the phosphate moiety of the substrate is the main chemical group interacting with the enzyme active site in the formation of the enzyme–substrate Michaelis complex. The enzyme does not catalyse transphosphorylation between substrate and concentrated nucleophilic acceptors (glycerol and methanol); nor does it catalyse H218O–inorganic phosphate oxygen exchange. It seems that no phosphoenzyme intermediate is formed in the catalytic pathway. Furthermore, during the enzymic hydrolysis of benzoyl phosphate in the presence of 18O-labelled water, only inorganic phosphate (and not benzoate) incorporates 18O, suggesting that no acyl enzyme is formed transiently. All these findings, as well as the strong dependence of kcat upon the leaving group pKa, suggest that neither a nucleophilic enzyme group nor general acid catalysis are involved in the catalytic pathway. The enzyme is competitively inhibited by Pi, but it is not inhibited by the carboxylate ions produced during substrate hydrolysis, suggesting that the last step of the catalytic process is the release of Pi. The activation energy values for the catalysed and spontaneous hydrolysis of benzoyl phosphate have been determined.
Dissertations / Theses on the topic "Substrate exchange kinetics"
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Hendry, Garth S., and Garth Hendry@baldwins com. "Dependence of substrate-water binding on protein and inorganic cofactors of photosystem II." The Australian National University. Research School of Biological Sciences, 2002. http://thesis.anu.edu.au./public/adt-ANU20041124.140348.
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The photosynthetic water oxidation reaction is catalyzed by an inorganic Mn4OxCaClyHCO3-z cluster at the heart of the oxygen evolving complex (OEC) in photosystem II. In the absence of an atomic resolution crystal structure, the precise molecular organization of the OEC remains unresolved. Accordingly, the role of the protein and inorganic cofactors of PSII (Ca2+, HCO3- and Cl-) in the mechanism of O2-evolution await clarification. In this study, rapid 18O-isotope exchange measurements were applied to monitor the substrate-water binding kinetics as a function of the intermediate S-states of the catalytic site (i.e. S3, S2 and S1) in Triton X-100 solubilized membrane preparations that are enriched in photosystem II activity and are routinely used to evaluate cofactor requirements. Consistent with the previous determinations of the 18O exchange behavior in thylakoids, the initial 18O exchange measurements of native PSII membranes at m/e = 34 (which is sensitive to the 16O18O product) show that the fast and slowly exchanging substrate-waters are bound to the catalytic site in the S3 state, immediately prior to O2 release. Although the slowly exchanging water is bound throughout the entire S-state cycle, the kinetics of the fast exchanging water remains too fast in the S2, S1 [and S0] states to be resolved using the current instrumentation, and left open the possibility that the second substrate-water only binds to the active site after the formation of the S3 state. Presented is the first direct evidence to show that fast exchanging water is already bound to the OEC in the S2 state. Rapid 18O-isotope exchange measurements for Ex-depleted PSII (depleted of the 17- and 23-kDa extrinsic proteins) in the S2 state reveals a resolvable fast kinetic component of 34k2 = 120 ± 14 s-1. The slowing down of the fast phase kinetics is discussed in terms of increased water permeation and the effect on the local dielectric following removal of the extrinsic subunits. In addition, the first direct evidence to show the involvement of calcium in substrate-water binding is also presented. Strontium replacement of the OEC Ca2+-site reveals a factor of ~3-4 increase in the 18O exchange of the slowly exchanging water across the S3, S2 and S1 states while the kinetics of the fast exchanging water remain unchanged. Finally, a re-investigation of the proposed role for bicarbonate as an oxidizable electron donor to photosystem II was unable to discern any 18O enrichment of the photosynthetically evolved O2 in the presence of 18O-bicarbonate. A working model for O2-evolution in terms of these results is presented.
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Manz, Dennis-Helmut. "Preorganized Bimetallic Nickel Complexes of Pyrazolate-Bridged Ligands for Cooperative Substrate Transformation." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-0023-3E41-E.
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Hendry, Garth S. "Dependence of substrate-water binding on protein and inorganic cofactors of photosystem II." Phd thesis, 2002. http://hdl.handle.net/1885/47151.
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The photosynthetic water oxidation reaction is catalyzed by an inorganic Mn4OxCaClyHCO3-z cluster at the heart of the oxygen evolving complex (OEC) in photosystem II. In the absence of an atomic resolution crystal structure, the precise molecular organization of the OEC remains unresolved. Accordingly, the role of the protein and inorganic cofactors of PSII (Ca2+, HCO3- and Cl-) in the mechanism of O2-evolution await clarification. In this study, rapid 18O-isotope exchange measurements were applied to monitor the substrate-water binding kinetics as a function of the intermediate S-states of the catalytic site (i.e. S3, S2 and S1) in Triton X-100 solubilized membrane preparations that are enriched in photosystem II activity and are routinely used to evaluate cofactor requirements. Consistent with the previous determinations of the 18O exchange behavior in thylakoids, the initial 18O exchange measurements of native PSII membranes at m/e = 34 (which is sensitive to the 16O18O product) show that the ‘fast’ and ‘slowly’ exchanging substrate-waters are bound to the catalytic site in the S3 state, immediately prior to O2 release. Although the slowly exchanging water is bound throughout the entire S-state cycle, the kinetics of the fast exchanging water remains too fast in the S2, S1 [and S0] states to be resolved using the current instrumentation, and left open the possibility that the second substrate-water only binds to the active site after the formation of the S3 state. Presented is the first direct evidence to show that fast exchanging water is already bound to the OEC in the S2 state. Rapid 18O-isotope exchange measurements for Ex-depleted PSII (depleted of the 17- and 23-kDa extrinsic proteins) in the S2 state reveals a resolvable fast kinetic component of 34k2 = 120 ± 14 s-1. The slowing down of the fast phase kinetics is discussed in terms of increased water permeation and the effect on the local dielectric following removal of the extrinsic subunits. In addition, the first direct evidence to show the involvement of calcium in substrate-water binding is also presented. Strontium replacement of the OEC Ca2+-site reveals a factor of ~3-4 increase in the 18O exchange of the slowly exchanging water across the S3, S2 and S1 states while the kinetics of the fast exchanging water remain unchanged. Finally, a re-investigation of the proposed role for bicarbonate as an oxidizable electron donor to photosystem II was unable to discern any 18O enrichment of the photosynthetically evolved O2 in the presence of 18O-bicarbonate. A working model for O2-evolution in terms of these results is presented.
Book chapters on the topic "Substrate exchange kinetics"
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Hillier, Warwick, Johannes Messinger, and Tom Wydrzynski. "Substrate Water 18O Exchange Kinetics in the S2 State of Photosystem II." In Photosynthesis: Mechanisms and Effects, 1307–10. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-3953-3_308.
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Kuby, Stephen A. "Isotope Exchange Studies and Kinetic Isotope Effects." In A Study of Enzymes: Volume I Enzyme Catalysis, Kinetics, and Substrate Binding, 253–82. CRC Press, 2019. http://dx.doi.org/10.1201/9780429291579-8.
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Bortiatynski, Jacqueline M., and Patrick G. Hatcher. "The Development of 13C Labeling and 13C NMR Spectroscopy Techniques to Study the Interaction of Pollutants with Humic Substances." In Nuclear Magnetic Resonance Spectroscopy in Environment Chemistry. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195097511.003.0007.
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Modern agricultural practices have contributed to the accumulation of herbicides, pesticides and their decomposition products in the soil. These pollutants are known to interact with soil organic matter to form covalent and/or noncovalent bonding associations. The covalent bonds are thought to result from addition or oxidative coupling reactions, some of which may be catalyzed by oxidoreductive enzymes. Noncovalent associations include such interactions as ion exchange, hydrogen bonding, protonation, charge transfer, ligand exchange, coordination through metal ions, van der Waals forces, and hydrophobic bonding. The association of pollutants with soil organic matter is an area of study that is of extreme interest for two reasons. First, dissolved organic matter present in lakes and streams is known to enhance the solubility of pollutants, which poses a real threat to the quality of fresh water supplies. Therefore, if we are to predict the movement of pollutants in the water table we need to have a mechanistic understanding of their interactions with dissolved humic materials. Second, early studies had indicated that some pollutants chemically bind to humic materials, thus reducing the risk of further transport and dispersion. If this chemical binding of the pollutants is irreversible, then this process may serve as a natural means for their detoxification. Regardless of the type of association, the first task in any mechanistic study is to characterize the reaction products structurally. In the case of noncovalent binding mechanisms, studies have focused on the physical characteristics of the process and not on the structure of the associated pollutant. Association studies are used to determine the sorption kinetics and transport of pollutants as well as their association constants. These types of studies utilize various techniques such as batch sorption, gas-purge desorption, column adsorption, and miscible displacement. All of these techniques are only capable of providing quantitative information on the amount of pollutant sorbed by a substrate. The study of the covalent binding of pollutants to humic substances has utilized 14C labeling in addition to various spectrometric techniques such as ultraviolet (UV) difference, fluorescence polarization and infrared (IR) spectroscopy.
Conference papers on the topic "Substrate exchange kinetics"
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Sekulic, Dusan P. "Wetting and Spreading of Liquid Metals Through Open Micro Grooves and Surface Alterations." In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82149.
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Surface tension driven flows of micro layers of complex liquids over substrates under reactive wetting conditions are greatly influenced by interface interactions and topography of surface alterations. For example, understanding of spreading of molten metals over metal substrates with complex topography may be interpreted as spreading over multiple connected networks of open micro channels. Hence, understanding of the kinetics of wetting and spreading of such reactive systems through micro channels is of a key interest. This keynote lecture will provide an overview of wetting/spreading phenomena related to migration of the molten metal micro layer over smooth, rough, and/or well-organized-topography surfaces, such as micro channels. Systems involving a liquid metal medium temperature range (Al-Si over Al), and a low temperature range (Pb-Sn and Ag-Sn over Cu and Cu-Sn) have been considered. Kinetics data involving triple line movement and its modeling will be supported by real-time in situ visualizations. Targeted applications of these fundamental studies involve art of brazing of compact aluminum heat exchangers for HVAC&R, thermal management for aerospace, and soldering processes (in particular lead-free) for electronics industries.
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George, C., E. Pfender, and H. D. Steffens. "Numerical Simulation of a Multi-Component Reacting Flow in a Supersonic DC Torch Nozzle." In ITSC 1996, edited by C. C. Berndt. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.itsc1996p0595.
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Abstract Maximizing dissociated species transport in plasma assisted chemical vapor deposition (CVD), is important in many low pressure plasma jet processes. To deposit high quality diamond by low pressure plasma assisted CVD, it is important to maximize the atomic hydrogen transport to the substrate. One route to process improvement is to explore ways in which unstable species transport can be maximized. A two-dimensional computational model of a supersonic contoured nozzle attached to a dc torch will be described for examining the chemical non-equilibrium of the flow. If the fluid dynamic time scales of interest are faster than the kinetic time scales of interest, it is believed that unstable precursor transport can be controlled, improved and optimized. This paper will examine an implicit formulation for the numerical simulation of a multi-component reacting Ar-H2 plasma. It is found that dissociation, ionization and charge exchange reactions must all be included in a reaction model. The ionic species significantly alter the temperature profiles upstream of nozzle choking. However, to increase the number of hydrogen atoms at the nozzle exit, the arc attachment should be positioned as close as possible to the converging-diverging nozzle throat.
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Mukherjee, Shiladitya, J. Vernon Cole, Kunal Jain, and Ashok Gidwani. "Water Management in PEM Fuel Cell: A Lattice-Boltzmann Modeling Approach." In ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2009. http://dx.doi.org/10.1115/fuelcell2009-85182.
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In Proton Exchange Membrane Fuel Cells (PEMFCs), water management and the effective transport of water through the gas-diffusion-layer (GDL) are key issues for improved performance at high power density and for durability during freeze-thaw cycles. The diffusion layer is a thin (∼150–350μm), porous material typically composed of a web of carbon fibers and particles, and is usually coated with hydrophobic Teflon to remove the excess water through capillary action. In-situ diagnostics of water movement and gas-reactant transport through this thin opaque substrate is challenging. Numerical analyses are typically based on simplified assumptions, such as Darcy’s Law and Leverett functions for the capillary pressure. The objective of this work is to develop a high fidelity CFD modeling and analysis tool to capture the details of multiphase transport through the porous GDL. The tool can be utilized to evaluate GDL material design concepts and optimize systems based on the interactions between cell design, materials, and operating conditions. The flow modeling is based on the Lattice Boltzmann Method (LBM). LBM is a powerful modeling tool to simulate multiphase flows. Its strength is in its kinetic theory based foundation, which provides a fundamental basis for incorporating intermolecular forces that lead to liquid-gas phase separation and capillary effects without resorting to expensive or ad-hoc interface reconstruction schemes. At the heart of the solution algorithm is a discrete form of the well-known Boltzmann Transport Equation (BTE) for molecular distribution, tailored to recover the continuum Navier-Stokes flow. The solution advances by a streaming and collision type algorithm, mimicking actual molecular physics, which makes it suitable for porous media involving complex boundaries. We developed a numerical scheme to reconstruct various porous GDL microstructures including Teflon loading. Single and multiphase LBM models are implemented to compute permeability. Predicted values are in good agreement with measured data. The present modeling approach resolves the GDL microstructures and captures the influence of fiber orientation on permeability and the influence of Teflon loading on the development of preferential flow paths through the GDL. These observations can potentially guide the development of novel GDL materials designed for efficient removal of water.