Fluid-phase Interaction Research Articles

The formation of volatile‐bearing djerfisherite in reduced meteorites

AbstractEnstatite meteorites, both aubrites and enstatite chondrites, formed under exceptionally reducing conditions, similar to the planet Mercury. Despite being reduced, the MESSENGER mission showed that the surface of Mercury is more enriched in volatiles (e.g., S, Na, K, Cl) than previously thought. To better understand the mineral hosts of these volatiles and how they formed, this work examines the chemistry and petrographic settings of a rare, K‐bearing sulfide called djerfisherite within enstatite chondrites and aubrites. The petrographic settings of djerfisherite within aubrites suggest this critical host of Cl formed after both the crystallization of troilite and exsolution of daubréelite. Djerfisherite is commonly observed as a rim on other sulfides and in contact with metal. We present an alteration model for djerfisherite formation in aubrite meteorites, whereby troilite and Fe‐Ni metal are altered through anhydrous, alkali‐ and Cl‐rich fluid metasomatism on the aubrite parent body to produce secondary djerfisherite. Moreover, we observe a loss of volatiles in djerfisherite within impact melted regions of the Miller Range 07139 EH3 chondrite and the Bishopville aubrite and explore the potential for impact devolatilization changes to sulfide chemistry on other reduced bodies in the Solar System. Vapor or fluid phase interactions are likely important in the formation of volatile‐rich phases in reduced systems. While most Na and K on the mercurian surface is expected to be hosted in feldspar, djerfisherite is likely a minor, but critical, reservoir for K, Na, and Cl. Djerfisherite present on reduced bodies, such as Mercury, may represent sulfides formed via late‐stage, primary metasomatism.

Application of machine learning to predict the time evolution of condensate to gas ratio for planning and management of gas-condensate fields

One of the most important parameters for the evaluation, forecast, and management of gas-condensate fields is the evolution of the condensate to gas ratio (CGR) over time. This parameter tends to decrease as reservoir pressure declines. In the conventional approach, gas and condensate samples are collected at the beginning of production and periodically later to conduct laboratory experiments on composition, CGR, and fluid properties. However, sample collection, transportation, and analysis require a lot of time and effort and could be very expensive. Likewise, dynamic models are also frequently used to predict CGR over time. However, these models could include many uncertainties due to ambiguous input data, including reservoir structures, fluid phase interaction, and reservoir property distribution. Therefore, the application of machine learning to predict the time evolution of CGR in this research could be a new and effective approach to supplement conventional methods.

Numerical analysis of particle injection effect on gas-liquid two-phase flow in horizontal pipelines using coupled MPPIC-VOF method

Pipeline transport of three-phase (gas, liquid, and solid particles) flows has become increasingly prevalent in various industrial applications. Due to complicated fluid phase interactions, experimental and numerical investigation of this type of flow can be very demanding. In this study, the coupled Eulerian–Lagrangian approach MPPIC-VOF is adopted, which is capable of capturing solid particle motion as well as fluid phase development simultaneously. Prior to three-phase flow simulation, two-phase air–water flow in a specific range of gas and liquid superficial velocities with slug and plug flow patterns is simulated. Then, polypropylene particles are injected as the solid phase into the air–water flow and the effects of particles on pressure drop, void fraction, and flow patterns are studied. The pressure drop and void fraction results are validated for both two-phase and three-phase flows by different correlations and experimental results. As a result of particle injection at the low concentration of 0.5%, void fraction increases by 13.7% and pressure drop changes on average by 18%, respectively. However, there was no significant change in the flow patterns.

Bilayer Interactions among Unsaturated Phospholipids, Sterols, and Ceramide

Using differential scanning calorimetry and lifetime analysis of trans-parinaric acid fluorescence, we have examined how cholesterol and cholesteryl phosphocholine (CholPC) affect gel-phase properties of palmitoyl ceramide (PCer) in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dioleyol-sn-glycero-3-phosphocholine (DOPC) bilayers. By 2H NMR, we also measured fluid-phase interactions among these lipids using deuterated analogs of POPC, PCer, and cholesterol. The PCer-rich gel phase in POPC bilayers (9:1 molar ratio of POPC to PCer) was partially and similarly dissolved (and thermostability decreased) by both cholesterol and CholPC (sterol was present equimolar to PCer, or in fourfold excess). In DOPC bilayers (4:1 DOPC/PCer molar ratio), CholPC was much more efficient in dissolving the PCer-rich gel phase when compared to cholesterol. This can be interpreted as indicating that PCer interaction with POPC was stronger than PCer interaction with DOPC. PCer-CholPC interactions were also more favored in DOPC bilayers compared to POPC bilayers. In the fluid POPC-rich phase, cholesterol increased the order of the acyl chain of d2-PCer much more than did CholPC. In DOPC-rich fluid bilayers, both cholesterol and CholPC increased d2-PCer acyl chain order, and the ordering induced by CholPC was more efficient in DOPC than in POPC bilayers. In fluid POPC bilayers, the ordering of 3-d1-cholesterol by PCer was weak. In summary, we found that in the gel phase, sterol effects on the PCer-rich gel phase were markedly influenced by the acyl chain composition of the fluid PC. The same was true for fluid-phase interactions involving the sterols. Our results further suggest that PCer did not display high affinity toward either of the sterols used. We conclude that the nature of unsaturated phospholipids (POPC versus DOPC) in bilayers has major effects on the properties of ceramide gel phases and on sterol-ceramide-phospholipid interactions in such complex bilayers.

Numerical investigation of the fluid-solid mixture flow using the FOCUS code

The fluid-solid mixture flow is the key phenomenon in the reactor core when severe accident happens, there are both fluid phase and solid phase in the migration of the molten corium. In this study, the discrete element method (DEM) is applied to model the interaction between solid bodies, the MPS method is adopted to simulate the fluid flows, and these two methods are coupled by the model of the solid and fluid phase interaction. The passively moving solid (PMS) model is adopted to modify the movement of moving particles so that several particles can form one solid body. The time step in the DEM model is different from that in the MPS method, thus a multiple time-step using inner iteration is carried out to solve this problem. The FOCUS (Fluid flOw CoUpling with Solid's movement) code is developed by the models and methods above using C++ language. The simulations and experiments about collapse of solid cylinder layers and he breaking of a water dam involving solid cylinder layers in two-dimension are carried out to validate FOCUS, and a simple three-dimensional case is also tested before the future work about severe accidents in reactor cores. The comparisons between calculation results and experimental data are in good agreements with the average relative error less than 8.4%, meaning the FOCUS is capable of simulating the fluid-solid mixture flow. It provides the foundation for the further work on simulations of the severe accidents in nuclear reactor cores.

Lagrangian coupling two-phase flow model to simulate current-induced scour beneath marine pipelines

This paper presents a Lagrangian coupling two-phase flow model for simulating scour processes beneath a marine pipeline with respect to the sediment and fluid phase interactions. Smoothed Particle Hydrodynamics (SPH) capability is employed to simulate sediment and fluid particles movement, respectively as the Newtonian and non-Newtonian fluids in the framework of two-phase flow modeling. The Sub-Particle Scale (SPS) model also is closured to the fluid phase solver to account for the turbulence effects. The soft contact approach is incorporated in the sediment phase to simulate the interparticle collisions during the local scouring. Following to the Lagrangian coupling model development, the current-induced scour beneath a pipe at tunnel erosion and early stages of lee-wake erosion were explored and then compared with the experiments. The obtained results illustrated the efficiency of the proposed two-phase flow model to reproduce the scour profiles evolution up to the early stages of lee-wake erosion. Within the presented model, the parameters such as pressure field and non-dimensional sediment transport rate beneath the pipe were also estimated.

Solid-phase classical complement activation by C-reactive protein (CRP) is inhibited by fluid-phase CRP–C1q interaction

C-reactive protein (CRP) interacts with phosphorylcholine (PC), Fcγ receptors, complement factor C1q and cell nuclear constituents, yet its biological roles are insufficiently understood. The aim was to characterize CRP-induced complement activation by ellipsometry. PC conjugated with keyhole limpet hemocyanin (PC-KLH) was immobilized to cross-linked fibrinogen. A low-CRP serum with different amounts of added CRP was exposed to the PC-surfaces. The total serum protein deposition was quantified and deposition of IgG, C1q, C3c, C4, factor H, and CRP detected with polyclonal antibodies. The binding of serum CRP to PC-KLH dose-dependently triggered activation of the classical pathway. Unexpectedly, the activation was efficiently down-regulated at CRP levels >150 mg/L. Using radial immunodiffusion, CRP–C1q interaction was observed in serum samples with high CRP concentrations. We propose that the underlying mechanism depends on fluid-phase interaction between C1q and CRP. This might constitute another level of complement regulation, which has implications for systemic lupus erythematosus where CRP is often low despite flare-ups.

Cellular Adhesion Mediated by Factor J, a Complement Inhibitor: EVIDENCE FOR NUCLEOLIN INVOLVEMENT

Factor J (FJ) is a complement inhibitor that acts on the classical and the alternative pathways. We demonstrated FJ-cell interactions in fluid phase by flow cytometry experiments using the cell lines Jurkat, K562, JY, and peripheral blood lymphocytes. FJ bound to plastic plates was able to induce in vitro adhesion of these cells with potency equivalent to fibronectin. As evidence for the specificity of this reaction, the adhesion was blocked by MAJ2, an anti-FJ monoclonal antibody, and by soluble FJ. Attachment of the cells required active metabolism and cytoskeletal integrity. The glycosaminoglycans heparin, heparan sulfate, or chondroitin sulfates A, B, and C inhibited to varying degrees the binding of FJ to cells, as did treatment with chondroitinase ABC. In the search for a putative receptor, a protein of 110 kDa was isolated by affinity chromatography, and microsequence analysis identified this protein as nucleolin. Confocal microscopy evidenced the presence of nucleolin in cell membrane by immunofluorescence with monoclonal (D3) and polyclonal anti-nucleolin antibodies in Jurkat cells. The interaction FJ-nucleolin was evidenced by Western blot and enzyme-linked immunosorbent assay. Furthermore, purified nucleolin and D3 inhibited adhesion of Jurkat cells to immobilized FJ, suggesting that the interaction was specific and that nucleolin mediated the binding.

Microencapsulation of Naproxen Using Rapid Expansion of Supercritical Solutions

The rapid expansion of supercritical solutions (RESS) process was used to produce polymeric microparticles or microspheres loaded with pharmaceuticals for drug delivery applications. Poly(L-lactic acid) (L-PLA), naproxen, and a mixture of naproxen/L-PLA were dissolved in supercritical CO 2 and precipitated by the RESS process. Composite particles appear as a naproxen core encapsulated in a polymer coating. The solubility of L-PLA and naproxen/L-PLA has been measured at 333.15 K and pressures ranging from 90 to 200 bar by using a dynamic flow apparatus. The lattice fluid theory of Sanchez and Lacombe was tested for its correlative and predictive capability of modeling these supercritical fluid mixtures. The solubility data are combined with morphology studies to investigate the effects of fluid phase interactions on particle formation using RESS.

Modelling Boom Clay Formation Porewater Chemistry: Ion Exchange Versus Dissolution Precipitation Mechanisms

The main objectives of the ANDRA/CCE study presented here is understanding how water in contact with a clay formation acquires its chemistry. The knowledge of the different processes involved should help determine the major parameters that are needed to achieve geochemical modelling. Several organisations (BGS, BRGM, CEA, CEN/SCK, CNRS, ERM and GRAM) are taking part in this project which is funded jointly by ANDRA and CEC. BRGM is more particularly in charge of modelling claywater equilibria from the study of the mechanisms of solidand fluid-phase interactions. The first results of this study are presented here.

Fibronectin dependent macrophage fibrin binding

Plasma fibronectin has been shown to increase the binding of fibrin monomer to macrophages in vitro. In the present study we began characterization of the mechanism underlying this fibronectin activity. Fragments of fibronectin containing the amino terminus enhanced macrophage fibrin binding to the same extent as intact fibronectin on an equimolar basis. However, fibronectin fragments containing the gelatin-binding domain or the cell-binding domain, but lacking the amino terminus, had no effect on fibrin binding. Fibronectin enhanced fibrin binding was not affected by the addition of synthetic peptides containing the RGD adhesion sequence. The ability of fibronectin to augment fibrin binding remained after paraformaldehyde fixation of macrophage monolayers. Fixation did not alter the basal levels of fibrin binding by macrophages. Preincubation of macrophages with exogenous fibronectin did not increase the binding of fibrin. Fibronectin enhanced fibrin binding remained unaltered after the removal of endogenous cell surface fibronectin by capping with F(ab')2 fragments of antibodies to fibronectin. These results suggest that the amino terminus of fibronectin supports the attachment of fibrin to macrophages by an initial fluid-phase interaction that precedes cellular binding and does not require a cellular response.

Fibronectin Dependent Macrophage Fibrin Binding

AbstractPlasma fibronectin has been shown to increase the binding of fibrin monomer to macrophages in vitro. In the present study we began characterization of the mechanism underlying this fibronectin activity. Fragments of fibronectin containing the amino terminus enhanced macrophage fibrin binding to the same extent as intact fibronectin on an equimolar basis. However, fibronectin fragments containing the gelatin-binding domain or the cell-binding domain, but lacking the amino terminus, had no effect on fibrin binding. Fibronectin enhanced fibrin binding was not affected by the addition of synthetic peptides containing the RGD adhesion sequence. The ability of fibronectin to augment fibrin binding remained after paraformaldehyde fixation of macrophage monolayers. Fixation did not alter the basal levels of fibrin binding by macrophages. Preincubation of macrophages with exogenous fibronectin did not increase the binding of fibrin. Fibronectin enhanced fibrin binding remained unaltered after the removal of endogenous cell surface fibronectin by capping with F(ab′)2 fragments of antibodies to fibronectin. These results suggest that the amino terminus of fibronectin supports the attachment of fibrin to macrophages by an initial fluid-phase interaction that precedes cellular binding and does not require a cellular response.

Interaction of heparin with fibronectin and isolated fibronectin domains

Fluorescence polarization, gel exclusion chromatography and affinity chromatography were used to characterize the interaction of heparins of different size with human plasma fibronectin (Fn) and several of its isolated domains. The fluid-phase interaction of Fn with heparin was dominated by the 30 kDa and 40 kDa Hep-2 domains located near the C-terminal ends of the A and B chains respectively. The 30 kDa Hep-2A domain from the heavy chain was indistinguishable from the 40 kDa Hep-2B domain in this respect; the presence of an additional type III homology unit in the latter had no effect on the binding. Evidence was provided that each Hep-2 domain has two binding sites for heparin. The N-terminal Hep-1 domain reacted weakly in fluid phase even though it binds strongly to immobilized heparin. Fn and Hep-2 fragments were rather undiscriminating in their reaction with fluoresceinamine-labelled heparins of different sizes. However, oligosaccharides smaller than the tetradecasaccharide (14-mer) bound Fn with a 5-10-fold lower affinity. These results suggest that the Hep-2 domains of Fn are able to recognize a broad spectrum of oligosaccharides that presumably vary significantly with respect to the amount and spatial distribution of charge.

Analysis of seismic patterns observed at Nevado del Ruiz volcano, Colombia during August – September 1985

The seismic activity of the Nevado del Ruiz volcano was monitored during August–September 1985 using a three-component portable seismograph station placed on the upper part of the volcano. The objective was to investigate the frequency content of the seismic signals and the possible sources of the volcanic tremor. The seismicity showed a wide spectrum of signals, especially at the beginning of September. Some relevant patterns from the collected records, which have been analyzed by spectrum analysis, are presented. For the purpose of analysis, the records have been divided into several categories such as long-period events, tremor, cyclic tremor episodes, and strong seismic activity on September 8, 1985. The origin of the seismic signals must be considered in relation to the dynamical and acoustical properties of fluids and the shape and dimensions of the volcano's conduits. The main results of the present experiment and analysis show that the sources of the seismic signals are within the volcanic edifice. The signal characteristics indicate that the sources lie in fluid-phase interactions rather than in brittle fracturing of solid components.

Platelet-neutrophil-smooth muscle cell interactions: lipoxygenase-derived mono- and dihydroxy acids activate cholesteryl ester hydrolysis by the cyclic AMP dependent protein kinase cascade

Fluid-phase interactions between hematologic cells and those of the vessel wall were studied in order to define a role for lipoxygenase products as cell signals in the control of vascular cholesterol metabolism. A functional parameter for hydroxy acids in this system has not been previously demonstrated. We report herein for the first time a biochemical effect of lipoxygenase-derived eicosanoids in the modulation of cholesterol metabolism in smooth muscle cells. Products of platelet-neutrophil interactions served as cell signals in vitro to modulate cholesterol metabolism. We demonstrate that 12-HETE, 12,20-DiHETE, and 12-HETE-1,20-dioic acid activate both lysosomal and cytoplasmic cholesteryl ester (CE) hydrolytic activities, although no effect was observed on CE synthetic (ACAT) activity. The platelet lipoxygenase product, 12-HETE, was the most effective stimulator of CE hydrolysis in the smooth muscle cell, and its conversion to 12,20-DiHETE and the dioic acid derivative by the neutrophils was not necessary for the activation of CE hydrolase. A 2-fold enhancement on CE hydrolysis occurred and was independent of any "cross-activation" by hydroxy acids on production of cyclooxygenase or other lipoxygenase products. The activation of cytoplasmic CE hydrolysis had a lesser cofactor dependence on bile salts in the presence of 12-HETE. This suggested a reduced requirement for surface-active agents in an enzyme-substrate interaction where enzymes are hydrolyzing insoluble lipid substrates. Moreover, 12-HETE induced an additive effect with several lipolytic hormones in the activation of CE catabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of fibronectin and its gelatin-binding domains with fluorescent-labeled chains of type I collagen.

Fluorescent probes have been used to obtain dissociation constants for the fluid-phase interaction of human plasma fibronectin and several of its gelatin-binding fragments with purified alpha chains of type I rat tail collagen, as well as with a cyanogen bromide fragment (CB7) of the alpha 1 chain in 0.02 M Tris buffer containing 0.15 M NaCl at pH 7.4. Addition of fibronectin to fluorescein-labeled collagen chains caused a dose-dependent increase in the fluorescence anisotropy which continued over several logs of titrant concentration. Scatchard-type plots of the anisotropy response were biphasic indicating the presence of one or more weak sites (Kd greater than microM) along the collagen chain in addition to a strong site characterized by Kd = 1.3 X 10(-8) M at 25 degrees C. Gelatin-binding fragments with Mr = 42,000, 60,000, and 72,000 also produced a biphasic response with Kd values for the high affinity site being 10- to 20-fold greater than for intact fibronectin. Binding of fibronectin and its fragments to fluorescent-labeled CB7 was essentially the same as to the whole alpha 1 chain. In all cases, the anisotropy response could be reversed or prevented by addition of excess unlabeled gelatin or CB7, but not by synthetic peptides spanning the collagenase cleavage site of alpha 1 (I). Studies of the temperature dependence of Kd for binding of fibronectin to the high affinity site on alpha 1 produced a value of +16 kcal/mol for the enthalpy of dissociation below 30 degrees C. Above this temperature, fibronectin appeared to undergo a subtle conformational transition characterization by a reduced affinity for collagen. This transition occurred in whole fibronectin but not in the gelatin-binding fragments and may involve disruption of intramolecular interactions between different domains.

A thermodynamic study of the interaction between human complement components C3b or C3(H2O) and factor B in solution.

The fluid-phase interaction between factor B and an activated form of C3 (C3b or C3(H2O)) is fundamental to the formation of the alternative complement pathway C3 convertase. The present study reports on the thermodynamic parameters that govern these interactions. The extrinsic fluorescent probe 8-anilino-1-naphthalene sulfonate (ANS) and factor B were found to act as competitive ligands in binding to C3b. Thus, complex formation between C3b or C3(H2O) and factor B could be monitored by the quenching of C3b/C3(H2O)-dependent ANS fluorescence upon the addition of B. Under physiological conditions (0.5 mM Mg2+, 37 degrees C, mu = 0.15), the Ka governing the binding of C3b to B was 2.5 X 10(6) M-1, whereas the interaction of C3(H2O) with factor B was of 5-fold lower affinity. Both reactions were endothermic, with the van't Hoff enthalpy being approximately +16.0 kcal mol-1 in each case. Thus, a large positive entropy change provides the net driving force in these interactions. Although Ka increased at higher Mg2+ concentrations, this was not an enthalpy-mediated phenomenon. Taken together, these data are consistent with hydrophobic interactions being dominant in C3b.B or C3(H2O).B complex formation. The enhancement of complex formation by Mg2+ and concomitant increase in delta S suggests that the metal ion plays a role in increasing the number of hydrophobic contacts.

Arterial cell interactions: mechanistic studies related to eicosanoid and growth factor-induced alterations in cholesterol metabolism.

Intracellular cholesterol accumulation in the arterial wall and the proliferation of intimal smooth muscle cells are the hallmarks of atherogenesis. Humoral fluid-phase interactions between arterial endothelial and smooth muscle cells have been studied in vivo and in vitro in an attempt to delineate whether these cells communicate in the regulation of intimal hyperplasia and cholesterol and lipoprotein metabolism in arterial smooth muscle cells.KeywordsSmooth Muscle CellCholesteryl EsterCholesterol MetabolismArterial Smooth Muscle CellCholesteryl Ester HydrolaseThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Interactions of arterial cells. Studies on the mechanisms of endothelial cell modulation of cholesterol metabolism in co-cultured smooth muscle cells.

Fluid phase interactions between arterial endothelial cells (EC) and smooth muscle cells (SMC) have been studied in vitro to assess the regulation of lipid metabolism in SMC (Hajjar, D. P., Falcone, D. J., Amberson, J. B., and Hefton, J. M. (1985) J. Lipid Res. 26, 1212-1223; Davies, P. F., Truskey, G. A., Warren, H. B., O'Connor, S. E., and Eisenhaure, B. H. (1985) J. Cell Biol. 101, 871-879). To identify EC-derived agonists which may modulate cholesterol metabolism in co-cultured SMC, we assessed the role of EC-derived eicosanoids and platelet-derived growth factor (PDGF) in the regulation of cholesteryl ester (CE) hydrolysis in SMC. The major eicosanoids synthesized by EC include PGI2 and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) and, to a lesser extent, prostaglandin E2. Exogenously added PGI2 and 12-HETE stimulated CE hydrolytic activity in SMC by 49 and 35%, respectively, when co-cultured with aspirin-treated EC. Aspirin-treated EC when co-cultured with SMC did not stimulate CE hydrolytic activity in SMC, as was the case with non-aspirin-treated EC, suggesting a role of eicosanoids in the regulation of cholesterol metabolism. Other humoral agents derived from EC such as PDGFc stimulated CE hydrolytic activity almost 2-fold in SMC cultured alone or co-cultured with EC. Aspirin-treated EC, incubated with 10 ng/ml PDGF, did not stimulate CE hydrolytic activity in co-cultured SMC. These results suggest that growth factor-promoting activity may enhance CE hydrolysis via the PGI2-cyclic AMP-CE hydrolysis cascade. This hypothesis supports our observations that PDGF stimulates PGI2 production in SMC. Elevated PGI2, in turn, can stimulate CE hydrolysis in these cells. Our findings suggest that the regulation of cholesterol metabolism in SMC can involve, at least in part, growth factors and EC-derived eicosanoids. These may play a central role in the regulation of hemostasis and the inflammatory response.

Interaction of gelatin with a fluorescein-labeled 42-kDa chymotryptic fragment of fibronectin.

A 42-kDa gelatin binding fragment of human plasma fibronectin was labeled with fluorescein and its fluid-phase interaction with gelatin was investigated. At 25 degrees C in 0.1 M Tris, 0.15 M NaCl, pH 7.3, a dissociation constant, Kd = 0.6 microM, was obtained from the dependence of fluorescence polarization on gelatin concentration. An identical value was obtained for the unlabeled fragment by competition. Binding was unaffected by higher concentrations of NaCl up to 1.0 M, but increased as much as 20-fold at low ionic strength. The dependence of Kd on temperature revealed that dissociation of the complex is accompanied by an increase in entropy. Thus, the interaction is not dominated by either hydrophobic or electrostatic forces; an important role for hydrogen binding is proposed.