Illite-smectites and the influence of burial diagenesis on the geochemical cycling of nitrogen

Clay Minerals ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 539-546 ◽  
Author(s):  
P. A. Schroeder ◽  
A. A. McLain
Keyword(s):  
Reaction Mechanisms ◽  
Ostwald Ripening ◽  
Precipitation Reaction ◽  
Oil Well ◽  
Burial Diagenesis ◽  
Fixed Nitrogen ◽  
Geochemical Cycling ◽  
Oil Generation ◽  
Fraction Increase ◽  
Changing Rate

AbstractFixed nitrogen in illite-smectites (I-S) has been measured for Miocene shales from a Gulf of Mexico oil well. Fixed N values for the <0.2 µm fraction increase with depth from 150 ppm (1000 m) to a maximum of 360 ppm (3841 m). This increase is coincident with illitization from 41% I in I-S to 75% I in I-S. Below 3841 m, fixed N values decrease to 190 ppm (4116 m) while I-S is maintained with a slight increase from 77 to 82%. The changes in fixed N with increasing illitization are consistent with the notion that illitization proceeds via both transformation and dissolution/ precipitation reaction mechanisms. The trend of decreasing fixed N in illitic I-S is compatible with surface-controlled crystal growth and Ostwald ripening mechanisms for illitization. The trend may also be linked to the timing of maximum NH] release from kerogen maturation during oil generation. The changing rate of NH+4 liberation from organic matter and multiple illitization reaction mechanisms can result in complex N geochemical cycling pathways throughout early diagenesis to metamorphism.

Usability of Geopolymers for Oil Well Cementing Applications: Reaction Mechanisms, Pumpability, and Properties

2016 ◽  
Author(s):  
Mahmoud Khalifeh ◽  
Helge Hodne ◽  
Arild Saasen ◽  
Obara Integrity ◽  
Ekom I. Eduok
Keyword(s):  
Reaction Mechanisms ◽  
Oil Well

Effect of Precipitation Method on Stoichiometry and Morphology of Hydroxyapatite Nanoparticles

2007 ◽  
Vol 330-332 ◽  
pp. 271-274 ◽  
Author(s):  
He Bin Shi ◽  
Hong Zhong ◽  
Yu Liu ◽  
Jin Yan Gu ◽  
Chang Sheng Yang
Keyword(s):  
Aqueous Solution ◽  
Crystal Size ◽  
Ostwald Ripening ◽  
Precursor Solution ◽  
Reaction Vessel ◽  
Reaction Process ◽  
Precipitation Method ◽  
Precipitation Reaction ◽  
Hydroxyapatite Nanoparticles ◽  
Coprecipitation Process

This paper reports synthesis of hydroxyapatite nanoparticles by three precipitation methods. Homogeneous aqueous solution of Ca(NO3)2 and H3PO4 was used as precursor solution, and NH3•H2O was precipitator. Calcium deficient hydroxyapatite nanorods were obtained by adding the precipitator into precursor solution, near stoichiometric hydroxyapatite nanoparticles were derived from adding precursor solution into the precipitator, and smaller hydroxyapatite nanoparticles were prepared by adding precipitator and precursor solution simultaneously into a reaction vessel. The stoichiometry of hydroxyapatite was mainly affected by pH at precipitation reaction process. The crystal size and shape of hydroxyapatite particles was related to Ostwald ripening. The stoichiometry and morphology of hydroxyapatite nanoparticles can be controllable by selecting suitable coprecipitation process.

Real-time atomistic simulation of the Ostwald ripening of TiO2 supported Au nanoparticles

Nanoscale ◽  
2020 ◽  
Vol 12 (37) ◽  
pp. 19142-19148 ◽  
Author(s):  
Beien Zhu ◽  
Rui Qi ◽  
Lina Yuan ◽  
Yi Gao
Keyword(s):  
Real Time ◽  
Atomistic Simulation ◽  
Au Nanoparticles ◽  
Ostwald Ripening ◽  
Atomic Simulation ◽  
Rate Determining Step ◽  
Changing Rate ◽  
Oswald Ripening

Atomic simulation shows a stagewise Oswald Ripening with changing rate-determining step. In the ripening, the particles exchange dimers among each other instead of monomers.

Simulation of Copper Precipitation in Fe-Cu Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 2579-2584 ◽  
Author(s):  
Ivan Holzer ◽  
Ernst Kozeschnik
Keyword(s):  
Ostwald Ripening ◽  
Early Stage ◽  
Peak Hardness ◽  
Precipitation Reaction ◽  
Precipitation Kinetics ◽  
Copper Precipitation ◽  
Cu Alloys ◽  
Fe Content ◽  
Composition Variation ◽  
Dense Distribution

During ageing of Fe-Cu alloys, for standard ageing conditions, peak hardness and strength is often observed after several hours. The significant strengthening is attributed to a dense distribution of very small bcc-Cu precipitates of 2-3 nm size. Using conventional numerical precipitation kinetics models for diffusion-controlled transformations, the kinetics of strengthening cannot be consistently described. One of the issues in this aspect is the fact that, after reaching peak hardness, a strong decrease in number density is observed experimentally, which cannot be explained by classical Ostwald ripening theory. In the present study, a new methodology for simulation of the copper precipitation kinetics in the early stage is suggested. The basic idea of this approach is to take into account the composition variation of the Cu-precipitates with respect to the Fe content during the precipitation reaction. The simulation results are compared to experimental data reported in literature. Consistent agreement between experiment and simulation can be achieved with the new methodology.

scholarly journals Precipitation Reaction Mechanisms of Mineral Deposits Simulated with a Fluid Mixing Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yan Zhang ◽  
Runsheng Han ◽  
Xing Ding ◽  
Yurong Wang ◽  
Pingtang Wei
Keyword(s):  
Reaction Mechanisms ◽  
Genetic Model ◽  
Metal Sulfide ◽  
Mixing Model ◽  
Fluid Mixing ◽  
Precipitation Reaction ◽  
Chloride Complexes ◽  
Ph Changes ◽  
Area Of Interest ◽  
Sulfide Precipitation

Nonmagmatic, carbonate-hosted epigenetic hydrothermal Pb–Zn deposits similar to those at the Huize Pb–Zn Mine are widespread across the Sichuan–Yunnan–Guizhou (SYG) polymetallic province. The precipitation mechanisms of these geologically intriguing deposits are an area of interest for many researchers. To simulate the underlying precipitation reaction mechanisms and dynamics of each aspect, a fluid mixing model for metal sulfide precipitation was used in a series of experiments, where solutions that contain Pb/Zn chloride complexes and sulfide were subjected to pH changes, water-rock reactions, and dilutions. Based on the results of these experiments, thermodynamic phase diagrams, and other experimental findings, a fluid mixing genetic model was developed for SYG Pb–Zn deposits, and this model was used to analyze the mechanisms of metal sulfide precipitation. The results indicate that acidic fluids in the form of chloride complexes transported Pb and Zn, whereas sulfide exists in the form of H2S within these fluids. The precipitation of metal sulfides occurs when these fluids undergo changes in pH, water-rock reactions, or isothermal dilution. The pH changes were found to be the most effective method for the induction of sulfide precipitation, followed by dilution and then water-rock reactions. The formation of sulfide precipitates due to pH changes, water-rock reactions, and dilution can be attributed to a single mechanism, i.e., changes in the pH of the fluid. Therefore, changes in pH are the primary mechanism of sulfide precipitation.

Polymorphic and Morphological Transformation during the Transition from a Propagating Band to Static Bands in the Nickel Hydroxide/Ammonia Liesegang System

2011 ◽  
Vol 312-315 ◽  
pp. 800-805 ◽  
Author(s):  
Mazen Al-Ghoul ◽  
Manal Ammar
Keyword(s):  
Experimental Study ◽  
Nickel Hydroxide ◽  
Pulse Propagation ◽  
Ostwald Ripening ◽  
Reaction Diffusion ◽  
Polymorphic Transition ◽  
The Other ◽  
Precipitation Reaction ◽  
Morphological Transformation ◽  
Ostwald Ripening Mechanism

We present an experimental study of the Ni+2/Ni(OH)2/NH3 reaction-diffusion system in a gel (agar). The system, which consists of a gel containing an inner electrolyte Ni+2 and a diffusing outer electrolyte (NH3/OH-), exhibits pulse propagation due to the concomitant precipitation reaction between Ni+2 and hydroxide ions and re-dissolution due to ammonia. During the propagation of the pulse, a transition to Liesegang banding is shown to take place. The bands are characterized by IR and XRD and are shown to consist of the polymorph -Ni(OH)2 whereas the pulse contains the other polymorph -Ni(OH)2. SEM measurements also reveal a morphological change accompanying the polymorphic transition between the pulse and the bands and uncovering an Ostwald ripening mechanism.

Precipitation in silicon: Microanalysis

1988 ◽  
Vol 46 ◽  
pp. 474-475
Author(s):  
R.W. Carpenter
Keyword(s):  
Transition Metals ◽  
Spatial Resolution ◽  
Thin Foil ◽  
Precipitation Reaction ◽  
High Current ◽  
Reaction Products ◽  
Carbon And Nitrogen ◽  
Dielectric Layers ◽  
Precipitation Processes ◽  
Areas Of Interest

Interest in precipitation processes in silicon appears to be centered on transition metals (for intrinsic and extrinsic gettering), and oxygen and carbon in thermally aged materials, and on oxygen, carbon, and nitrogen in ion implanted materials to form buried dielectric layers. A steadily increasing number of applications of microanalysis to these problems are appearing. but still far less than the number of imaging/diffraction investigations. Microanalysis applications appear to be paced by instrumentation development. The precipitation reaction products are small and the presence of carbon is often an important consideration. Small high current probes are important and cryogenic specimen holders are required for consistent suppression of contamination buildup on specimen areas of interest. Focussed probes useful for microanalysis should be in the range of 0.1 to 1nA, and estimates of spatial resolution to be expected for thin foil specimens can be made from the curves shown in Fig. 1.

A TEM investigation of a hyper-eutectic lead-tin alloy

1988 ◽  
Vol 46 ◽  
pp. 562-563
Author(s):  
John A. Sutliff
Keyword(s):  
Volume Diffusion ◽  
Eutectic Mixture ◽  
Precipitation Reaction ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Discontinuous Precipitation Reaction ◽  
Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

Analyzing reactions of single mechanoenzyme molecules by light microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 426-427
Author(s):  
Jeff Gelles
Keyword(s):  
Image Processing ◽  
Reaction Mechanisms ◽  
Transient State ◽  
Nanometer Scale ◽  
Reaction Intermediates ◽  
Enzyme Molecule ◽  
Directed Movement ◽  
Enzyme Molecules ◽  
Individual Enzyme ◽  
Single Reaction

Mechanoenzymes are enzymes which use a chemical reaction to power directed movement along biological polymer. Such enzymes include the cytoskeletal motors (e.g., myosins, dyneins, and kinesins) as well as nucleic acid polymerases and helicases. A single catalytic turnover of a mechanoenzyme moves the enzyme molecule along the polymer a distance on the order of 10−9 m We have developed light microscope and digital image processing methods to detect and measure nanometer-scale motions driven by single mechanoenzyme molecules. These techniques enable one to monitor the occurrence of single reaction steps and to measure the lifetimes of reaction intermediates in individual enzyme molecules. This information can be used to elucidate reaction mechanisms and determine microscopic rate constants. Such an approach circumvents difficulties encountered in the use of traditional transient-state kinetics techniques to examine mechanoenzyme reaction mechanisms.

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