scholarly journals Molecular-scale origins of wettability at petroleum–brine–carbonate interfaces

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Paul Fenter ◽  
Tianzhu Qin ◽  
Sang Soo Lee ◽  
Mohammed B. AlOtaibi ◽  
Subhash Ayirala ◽  
...  
Keyword(s):  
Interfacial Layer ◽  
Structural Changes ◽  
Interface Structure ◽  
Chemical Processes ◽  
Wetting Layer ◽  
Central Concept ◽  
Molecular Scale ◽  
Scale Behavior ◽  
Petroleum Oil ◽  
Parallel Measurements

AbstractWettability control of carbonates is a central concept for enhanced petroleum recovery, but a mechanistic understanding of the associated molecular-scale chemical processes remains unclear. We directly probe the interface of calcium carbonate (calcite) with natural petroleum oil, synthetic petroleum analogues, and aqueous brines to understand the molecular scale behavior at this interface. The calcite–petroleum interface structure is similar whether or not calcite was previously exposed to an aqueous brine, and is characterized by an adsorbed interfacial layer, significant structural changes within the calcite surface, and increased surface roughness. No evidence for an often-assumed thin-brine wetting layer at the calcite–petroleum interface is observed. These features differ from those observed at the calcite–brine interface, and for parallel measurements using model synthetic petroleum mixtures (consisting of representative components, including dodecane, toluene, and asphaltene). Changes to the interface after petroleum displacement by aqueous brines are also discussed.

scholarly journals Inhibitory effect of okadaic acid derivatives on protein phosphatases. A study on structure-affinity relationship

1992 ◽  
Vol 284 (2) ◽  
pp. 539-544 ◽  
Author(s):  
A Takai ◽  
M Murata ◽  
K Torigoe ◽  
M Isobe ◽  
G Mieskes ◽  
...  
Keyword(s):  
Okadaic Acid ◽  
Structural Changes ◽  
Protein Phosphatases ◽  
Inhibitory Effect ◽  
Chemical Processes ◽  
Hydroxyl Group ◽  
Confidence Limits ◽  
X Ray ◽  
Structural Modifications

The effect of structural modifications of okadaic acid (OA), a polyether C38 fatty acid, was studied on its inhibitory activity toward type 1 and type 2A protein phosphatases (PP1 and PP2A) by using OA derivatives obtained either by isolation from natural sources or by chemical processes. The dissociation constant (Ki) for the interaction of OA with PP2A was estimated to be 30 (26-33) nM [median (95% confidence limits)]. The OA derivatives used and their affinity for PP2A, expressed as Ki (in brackets) were as follows: 35-methyl-OA (DTX1) [19 (12-25) pM], OA-9,10-episulphide (acanthifolicin) [47 (25-60) pM], 7-deoxy-OA [69 (31-138) pM], 14,15-dihydro-OA [315 (275-360) pM], 2-deoxy-OA [899 (763-1044) pM], 7-O-palmitoyl-OA [greater than 100 nM], 7-O-palmitoyl-DTX1 [greater than 100 nM], methyl okadate [much greater than 100 nM], 2-oxo-decarboxy-OA [much greater than 100 nM] and the C-15-C-38 fragment of OA [much greater than 100 nM]. The sequence of the affinity of these derivatives for PP1 was essentially the same as that observed with PP2A, although the absolute values of Ki were very different for the enzymes. The inhibitory effect of OA on PP2A was reversed by applying a murine monoclonal antibody against OA, which recognizes modifications of the 7-hydroxyl group of the OA molecule. It has been shown by n.m.r. spectroscopy and X-ray analysis that one end (C-1-C-24) of the OA molecule assumes a circular conformation. The present results suggest the importance of the conformation for the inhibitory action of OA on the protein phosphatases. The ratios of the Ki values for PP1 to that for PP2A, which were within the range 10(3)-10(4), tended to be smaller for the derivatives with lower affinity, indicating that the structural changes in OA impaired the affinity for PP2A more strongly than that for PP1.

Some Infrared Studies on the Vulcanization of Rubber

1946 ◽  
Vol 19 (1) ◽  
pp. 66-85 ◽  
Author(s):  
N. Sheppard ◽  
G. B. B. M. Sutherland
Keyword(s):  
Carbon Black ◽  
Structural Changes ◽  
Physical And Mechanical Properties ◽  
Physical Methods ◽  
Structural Problems ◽  
Rubber Compounds ◽  
Molecular Scale ◽  
Infrared Studies ◽  
Preliminary Account ◽  
Relationship Of

Abstract The two most effective ways of altering the physical and mechanical properties of natural rubber are vulcanization and the addition of carbon black. There is, however, little understanding of the structural changes brought about by these processes, in spite of extensive research by chemical and physical methods. For instance, in vulcanization it is not yet decided how the sulfur atoms are incorporated in the rubber polymer, what proportion are in bridges formed between the isoprene chains, whether such bridges are formed by —C—S—S—C— or —C—S—C— links, whether one double bond is broken for each sulfur atom incorporated, and so on. An ancillary problem is the effect of certain “accelerators” on the speed of vulcanization, about which even less is known. Again in the case of reinforcement of rubber by materials such as carbon black, there is controversy on the structural relationship of the carbon black and the rubber. Until such structural problems have been solved on the molecular scale there is little hope of controlling the macroscopic properties of rubber compounds in a truly scientific manner. This paper gives a preliminary account of the application of infrared spectroscopy to some of these problems.

Upgrading a Large Municipal Sewage Treatment Plant by a Combination of Biological and Chemical Processes

1990 ◽  
Vol 22 (7-8) ◽  
pp. 105-112 ◽  
Author(s):  
H. H. Hahn ◽  
E. Hoffmann ◽  
A. Kleinschmidt ◽  
R. Klute
Keyword(s):  
Biological Treatment ◽  
Structural Changes ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Chemical Processes ◽  
Plant Performance ◽  
Municipal Sewage ◽  
The Past

The Standards controlling sewage treatment are continuously in development. Thus, upgrading existing plants is a frequently encountered problem. In the past this meant structural changes, mostly in terms of enlargement of existing facilities or addition of new units. More recently the possibilities of improving plant performance through chemicals addition (inducing precipitation and coagulation) with or without intensified biological treatment have been explored. Chemicals addition has become necessary in many instances due to the tightening of standards for phosphorous concentrations in the plant effluent. The present discussion is based on a case study where possibilities and limits of chemical and/or biological upgrading have been investigated. The analysis showed that neither chemical stages nor secondary biological stages alone can guarantee the effluent standards formulated by the water authorities.

COMPUTER SIMULATION OF STRUCTURAL CHANGES IN PHOSPHOLIPID BILAYERS

2000 ◽  
Vol 11 (01) ◽  
pp. 153-158 ◽  
Author(s):  
ARAM A. SHAHINIAN ◽  
ARMEN H. POGHOSYAN ◽  
HAMLET G. BADALYAN
Keyword(s):  
Aqueous Solution ◽  
Computer Simulation ◽  
Structural Changes ◽  
Relative Concentration ◽  
Molecular Fragment ◽  
Phospholipid Bilayers ◽  
Phospholipid Bilayer ◽  
Bilayer Thickness ◽  
Hydrocarbon Chains ◽  
Molecular Scale

Using molecular-scale computer simulation, we show that structural changes may take place in phospholipid bilayers in an aqueous solution as we vary the relative concentration of water to phospholipids, the bilayer thickness, the inclination angle of the choline, dipole molecular fragment with respect to the bilayer surface, and the conformation of hydrocarbon chains of phospholipid in the hydrophobic volume of the bilayer. It is shown that in the hydrophobic volume of the bilayer, an interpenetration of the hydrocarbon chains located on opposite sides of the phospholipid bilayer takes place.

Interfacial bonding of chromium-doped copper/diamond composites fabricated by powder metallurgy method

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040050 ◽  
Author(s):  
Shanquan Jia ◽  
Yu Su ◽  
Leandro Bolzoni ◽  
Fei Yang
Keyword(s):  
Interfacial Layer ◽  
Electronic Devices ◽  
Hot Forging ◽  
Copper Matrix ◽  
Interface Layer ◽  
Interface Structure ◽  
Diamond Surface ◽  
Powder Metallurgy Method ◽  
Power Electronic ◽  
Diamond Particles

Copper/diamond composites can be used as heat-sink materials for high-power electronic devices due to their potential high thermal conductivity. However, it is challenging to obtain well-bonded interface between the copper matrix and the diamond particles. In this paper, we fabricated copper/diamond composites with [Formula: see text] wt.% of chromium additive ([Formula: see text], 3 and 7.4, and the corresponding composite was referred to as 1Cr-Cu/Dia, 3Cr-Cu/Dia and 7Cr-Cu/Dia, respectively) by hot forging of powder preforms. Results showed that only Cr3C2 interfacial layer formed between the copper matrix and the diamond particles for the 1Cr-Cu/Dia and 3Cr-Cu/Dia composites with a thickness of about 100 and 500 nm, respectively. A Cr/Cr3C2 dual layer interface formed in the 7Cr-Cu/Dia composite and its thickness was [Formula: see text]m. The coverage of diamond surface by the interface layer increased with increasing the adding amount of chromium in the composites. The 3Cr-Cu/Dia composite achieved the highest relative density and bonding strength, comparing to 1Cr-Cu/Dia and 7Cr-Cu/Dia composites, attributed to the formation of an optimal interface structure.

The Hydrophily of Some Lacquers for Electrical Use

2020 ◽  
Vol 57 (1) ◽  
pp. 122-132
Author(s):  
Adriana-Mariana Bors ◽  
Alina-Ruxandra Caramitu ◽  
Dorian Marin ◽  
Iosif Lingvay
Keyword(s):  
Thermal Analysis ◽  
Dielectric Loss ◽  
Water Uptake ◽  
Structural Changes ◽  
Volume Resistivity ◽  
Chemical Processes ◽  
Polar Groups ◽  
Mass Losses ◽  
Different Types ◽  
Maximum Water

Through gravimetric determinations, volume resistivity, dielectric spectroscopy, and comparative thermal analysis (TG, DTA and DTG), the interactions between the distilled water and three different types of alkyd-epoxy-melamine, epoxy and polyurethane lacquers were studied. From the experimental determinations it was found that after 700 h of immersion in water at 20 � 2�C the alkyd-epoxy-melamine based lacquer has a maximum water uptake, respectively 1.76%, followed by the epoxy lacquer 1.4% and polyurethane 0.93%. The thermal analysis sugests that because the water retained by the investigated polymers does not change the TG diagrams in the temperature range up to 150 �C, which suggests that the weight increase of the samples during the immersion could be due to some chemical processes between the water and polymer by which the chemistry structure of the polymer changes. Through electrical measurementes one can observe that after the immersion in water (over 700 hours), dielectric loss increases and the volume resistivity (measured in DC) of the investigated lakes decreases, which is explained by the increasing of polar groups (-OH) in the polymer structure. A comparative analysis of the experimental data reveals that in electrical applications the lacquer LS (polyurethane) is superior to the lacquers L-528 (alkyd-epoxy-melamine) and LG (epoxy), because it has no mass losses (structural changes) up to 280�C it has a volume resistivity of about 21 % higher than L-G, and about 300 % higher than L-528, and has water uptake and dielectric loss substantially lower comparing to L-528 and L-G.

Calcium isotope fractionation in groundwater: Molecular scale processes influencing field scale behavior

2013 ◽  
Vol 119 ◽  
pp. 93-116 ◽  
Author(s):  
Jennifer L. Druhan ◽  
Carl I. Steefel ◽  
Kenneth H. Williams ◽  
Donald J. DePaolo
Keyword(s):  
Isotope Fractionation ◽  
Calcium Isotope ◽  
Field Scale ◽  
Molecular Scale ◽  
Scale Behavior

Structural changes at hydrophobic/hydrophilic interfaces induced by thermal changes and isotopic composition of the water

1979 ◽  
Vol 57 (5) ◽  
pp. 478-482 ◽  
Author(s):  
Fred Y. Fujiwara ◽  
Leonard W. Reeves
Keyword(s):  
Isotopic Composition ◽  
Structural Changes ◽  
Interface Structure ◽  
X Ray Diffraction ◽  
Chloride System ◽  
Structure Transition ◽  
Thermally Induced ◽  
Nmr Parameters ◽  
Thermal Changes ◽  
Remote Participation

A lyomesophase prepared from decylammorium tetrafluoroborate, ammonium tetrafluoroborate, and water, which orients in a magnetic field perpendicular to the directors (type II), has been investigated with respect to the isotopic composition, H2O/D2O of the aqueous compartment at constant overall chemical composition. An effect of the isotopic composition of the water has been discovered, which influences the packing of the water and tetrafluoroborate ions at the interface. An interface structure transition occurs at ∼ 14 mol% D2O in H2O. The ammonium ions, which do not form part of the first bound layer at the interface, are affected to a much smaller degree and the sudden changes in the direction of variation of nmr parameters are not observed for this ion. The interface structure at > 14 mol% D2O evidently does include more remote participation of NH4+ ions.Recent low angle X-ray diffraction studies, available to us, indicate that the mesophases which orient in magnetic fields have two levels of structure, the packing of amphiphiles in discrete anisotropic micelles and the super-packing of the micelles themselves. These studies now enable us to reinterpret other similar thermally induced structural changes in the interface, from results previously encountered, in the decylammonium chloride system. It is possible to have changes in the packing of water, amphiphiles, and ions at the interface without changes in the superstructure. Such changes in interface packing might well go undetected in a measurement of bulk properties but are revealed by measurement of nmr parameters for the oriented mesophase of different species involved in the interface structure. The isotope effect on structural packing at the interface is absent in two other mesophases investigated.

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