Uncovering Mysteries of Waxphaltenes: Meticulous Experimental Studies of Field and Lab Deposits Unveil Nature of Wax-Asphaltene Intermolecular Interactions

2021 ◽  
Author(s):  
Janaina I. S. Aguiar ◽  
Hamidreza Samouei ◽  
Amir Mahmoudkhani
Keyword(s):  
Intermolecular Interactions ◽  
Experimental Studies ◽  
Compositional Analysis ◽  
Proton Nuclear Magnetic Resonance ◽  
Medium Size ◽  
Scanning Calorimetry ◽  
Wax Content ◽  
Access To The Field ◽  
Paraffin Waxes ◽  
Made In

Abstract In recent years, the utilization of modern sampling tools provided access to the field deposits from several offshore and onshore wells producing asphaltenic crudes. Compositional analysis of field deposits revealed the presence of asphaltenes and wax as major fractions, while system conditions traditionally implied precipitation and deposition of asphaltenes only. Most of the previous studies on organic deposition have been conducted with the key assumption that aggregation and precipitation of wax and asphaltene occur independently. A few researchers investigated the solubility parameter's alteration, but they did not incorporate waxes found in the oilfield deposits. This study aims to investigate the nature of "waxphaltenes"; from intermolecular interactions between asphaltenes and wax in samples collected from fields and made in the laboratory. Asphaltenes samples were extracted and fully characterized by proton nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). Paraffin waxes were identified using gas chromatography (GC), differential scanning calorimetry (DSC), NMR, and FTIR. Precipitation tests of asphaltenes with n-heptane at high temperature were performed both in the presence and absence of wax; GC, NMR and FTIR techniques evaluated the precipitates and the material dispersed in solution. It was found that asphaltenes co-precipitated with waxes even at higher temperatures than the normal wax appearance temperature (WAT) of the crude oil or the model solutions and that long and medium size paraffin waxes had higher tendencies to coprecipitate with asphaltenes than either short chain or very long chain paraffin hydrocarbons. The results also indicated that the amount of wax that co-precipitates with asphaltenes was more related to asphaltene structure but is independent of the asphaltenes or wax content. Heteroatoms played an important role in the interactions between wax and asphaltenes during precipitation and separation.

ZnCdO/ZnMgO and ZnO/AlGaN Heterostructures for UV and Visible Light Emitters

2005 ◽  
Vol 892 ◽  
Author(s):  
Andrei Osinsky ◽  
Jianwei Dong ◽  
J. Q. Xie ◽  
B. Hertog ◽  
A. M. Dabiran ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Compositional Analysis ◽  
Optical Emission ◽  
Rf Plasma ◽  
Light Emitters ◽  
Time Resolved ◽  
Light Emitting ◽  
Spatially Resolved ◽  
Time Resolved Photoluminescence ◽  
Made In

AbstractThis paper reviews of some of the progress made in the development of ZnO-based light emitting diodes (LEDs). n-ZnO/p-AlGaN-based heterostructures have been successfully for the fabrication of UV emitting LEDs that have operated at temperatures up to 650K, suggesting an excitonic origin for the optical transitions. RF-plasma-assisted molecular beam epitaxy has been used to grow epitaxial CdxZn1-xO films on GaN/sapphire structure. These films have a single-crystal wurtzite structure as demonstrated by structural and compositional analysis. High quality CdxZn1-xO films were grown with up to x=0.78 mole fraction as determined by RBS and SIMS techniques. Optical emission ranging from purple (Cd0.05Zn0.95O) to yellow (Cd0.29Zn0.71O) was observed. Compositional fluctuations in a Cd0.16Zn0.84O films were not detected by spatially resolved CL measurements, although intensity fluctuation with features of ∼0.5 μm diameter were seen on the intensity maps. Time resolved photoluminescence shows multi-exponential decay with 21 psec. and 49±3 psec. lifetimes, suggesting that composition micro-fluctuations may be present in Cd0.16Zn0.84O film.

Synthesis and properties of a benzoxazine monomer containing maleimide and biphenyl groups

2021 ◽  
pp. 095400832199674
Author(s):  
Tao Guo ◽  
Yang Fan ◽  
Chang Bo ◽  
Zhang Qi ◽  
Han Tao ◽  
...  
Keyword(s):  
Weight Loss ◽  
Loss Rate ◽  
Proton Nuclear Magnetic Resonance ◽  
Significant Weight Loss ◽  
Scanning Calorimetry ◽  
Weight Loss Rate ◽  
Reaction Heat ◽  
H Nmr ◽  
Curing Reaction ◽  
Dsc Curves

Benzoxazine resin exhibits excellent properties and is widely used in many fields. Herein, the synthesis of a novel compound, the bis(2,4-dihydro-2 H-3-(4- N-maleimido)phenyl-1,3-benzoxazinyl)biphenyl (BMIPBB), has been reported, which was synthesized by reacting N-(4-aminophenyl)maleimide (APMI), formaldehyde, and 4,4’-dihydroxybiphenyl. 1,3,5-three(4-(maleimido)phenyl)-1,3,5-triazine (TMIPT) was formed as an intermediate during the reaction. The proton nuclear magnetic resonance (1H-NMR) and Fourier transform-infrared (FTIR) spectroscopy experiments were conducted to determine the structure of BMIPBB. BMIPBB was obtained as a reddish-brown solid in 40.1% yield. The thermal properties of BMIPBB were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Analysis of the DSC curves revealed that the broad peak representing the release of curing reaction heat appeared in the temperature range of 140–330°C. The peak temperature was 242.59°C and the heat of the reaction was 393.82 J/g, indicating that the rate of the curing reaction was low and the heat of the reaction was high. Analysis of the TGA results revealed that the weight loss rate was 5% at 110°C. The monomer exhibited a significant weight loss in the range of 320–500°C. The compound lost 50% of its weight at a temperature of 427°C.

scholarly journals β-Cyclodextrin/Triclosan Complex-Grafted Methacrylated Glycol Chitosan Hydorgel by Photocrosslinking via Visible Light Irradiation for a Tissue Bio-Adhesive

2021 ◽  
Vol 22 (2) ◽  
pp. 700
Author(s):  
Young Jae Moon ◽  
Sun-Jung Yoon ◽  
Jeung-Hyun Koo ◽  
Yihyun Yoon ◽  
Hye Jun Byun ◽  
...  
Keyword(s):  
Wound Healing ◽  
Bacterial Infection ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Light Irradiation ◽  
Tissue Adhesive ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Glycol Chitosan

Accelerating wound healing with minimized bacterial infection has become a topic of interest in the development of the new generation of tissue bio-adhesives. In this study, we fabricated a hydrogel system (MGC-g-CD-ic-TCS) consisting of triclosan (TCS)-complexed beta-cyclodextrin (β-CD)-conjugated methacrylated glycol chitosan (MGC) as an antibacterial tissue adhesive. Proton nuclear magnetic resonance (1H NMR) and differential scanning calorimetry (DSC) results showed the inclusion complex formation between MGC-g-CD and TCS. The increase of storage modulus (G’) of MGC-g-CD-ic-TCS after visible light irradiation for 200 s indicated its hydrogelation. The swollen hydrogel in aqueous solution resulted in two release behaviors of an initial burst and sustained release. Importantly, in vitro and in vivo results indicated that MGC-g-CD-ic-TCS inhibited bacterial infection and improved wound healing, suggesting its high potential application as an antibacterial tissue bio-adhesive.

scholarly journals Thermodynamics and Intermolecular Interactions of Nicotinamide in Neat and Binary Solutions: Experimental Measurements and COSMO-RS Concentration Dependent Reactions Investigations

2021 ◽  
Vol 22 (14) ◽  
pp. 7365
Author(s):  
Piotr Cysewski ◽  
Maciej Przybyłek ◽  
Anna Kowalska ◽  
Natalia Tymorek
Keyword(s):  
Intermolecular Interactions ◽  
Vibrational Energy ◽  
Perfect Match ◽  
Zero Point ◽  
Heat Capacity Change ◽  
Free Energies ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Capacity Change ◽  
Self Association

In this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential scanning calorimetry was used to characterize the fusion thermodynamics of nicotinamide. In particular, the heat capacity change upon melting was measured. The experimental data were interpreted by means of COSMO-RS-DARE (conductor-like screening model for realistic solvation–dimerization, aggregation, and reaction extension) for concentration dependent reactions. The solute–solute and solute–solvent intermolecular interactions were found to be significant in all of the studied systems, which was proven by the computed mutual affinity of the components at the saturated conditions. The values of the Gibbs free energies of pair formation were derived at an advanced level of theory (MP2), including corrections for electron correlation and zero point vibrational energy (ZPE). In all of the studied systems the self-association of nicotinamide was found to be a predominant intermolecular complex, irrespective of the temperature and composition of the binary system. The application of the COSMO-RS-DARE approach led to a perfect match between the computed and measured solubility data, by optimizing the parameter of intermolecular interactions.

FURTHER STUDIES ON NATURAL SELECTION AMONG HYBRIDS OF CARDUUS ACANTHOIDES AND CARDUUS NUTANS

1964 ◽  
Vol 42 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
R. J. Moore ◽  
G. A. Mulligan
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Parental Species ◽  
Experimental Studies ◽  
Great Decrease ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Experimental Plots ◽  
Better Than ◽  
Made In

A third 5-year survey made in 1962 of Carduus acanthoides, C. nutans, and their hybrids in Grey Co., Ontario, revealed that a great decrease in these populations had occurred. C. acanthoides and hybrids similar to this species had survived better than C. nutans but very little spread of either species seemed to have occurred in 1957–1962. In experimental plots the hybrid has been made and backcrossed to the parental species. The species differ in chromosome number (C. acanthoides, 2n = 22; C. nutans, 2n = 16) and hybrids have intermediate numbers. Evidence was found from field and experimental studies that the progeny of the F1 hybrid included a greater proportion of seedlings with the higher chromosome numbers than with the lower and intermediate numbers. It is suggested that this selection may operate through the rejection of the longer chromosomes received from C. nutans, which, in certain zygotic combinations may constitute an excess of chromatin lethal to the zygote.

Using Ultrathin-Film, Modulated Composites to Control the Reaction Mechanism of Ternary Compound Formation

1991 ◽  
Vol 238 ◽  
Author(s):  
Loreli Fister ◽  
David C. Johnson
Keyword(s):  
Ternary Compound ◽  
Reaction Pathway ◽  
Experimental Parameter ◽  
Ultrathin Film ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Compound Formation ◽  
One Dimensional ◽  
X Ray ◽  
Made In

ABSTRACTA predictable, controllable approach to the synthesis of ternary compounds through known intermediates is presented. Thin and ultrathin film superlattices were made in the Mo-Se, Cu-Se and Mo-Cu systems. Differential scanning calorimetry, low- and high-angle x-ray diffraction were used to assess the interdiffusion and nucleation reactions between elemental layers in these one-dimensional crystals. The experimental parameter modulation distance was used to influence the interfacial reactions. The results from each binary system were then used to predict the reaction pathway in the synthesis of a ternary compound, Cu2Mo6Se8. Superlattices with two different lengthscales were investigated. In the first, only one intermediate, MoSe2 which typically crystallizes at ∼200'C, is observed prior to the crystallization of Cu2Mo6Se8. In the second, no crystalline intermediates are observed below 6000 C.

EFFECT OF DRUG TO B-CYCLODEXTRIN RATIO AND METHOD OF COMPLEXATION IN THE DEVELOPMENT OF B-CYCLODEXTRIN INCLUSION COMPLEX OF OFLOXACIN

INDIAN DRUGS ◽  
2013 ◽  
Vol 50 (12) ◽  
pp. 34-40
Author(s):  
M Panchpuri ◽  
◽  
D Singh ◽  
A Semalty ◽  
M. Semalty
Keyword(s):  
Inclusion Complex ◽  
In Vitro Dissolution ◽  
Molar Ratio ◽  
Dissolution Profile ◽  
Scanning Calorimetry ◽  
Dissolution Study ◽  
Drug Content ◽  
Kneading Method ◽  
Made In

Ofloxacin, a second generation fluoroquinolone, shows poor aqueous solubility and dissolution profile. Thus, ofloxacin–β-cyclodextrin complexes were prepared to improve its dissolution by imparting an environment of improved hydrophilicity. Ofloxacin was complexed with β-cyclodextrin (in 1:1 and 1:2 molar ratio) by two different methods namely, solvent evaporation and kneading method. These inclusion complexes were evaluated for solubility, drug content, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X ray powder diffraction (XRPD) and in vitro dissolution study. The highest drug content (35.45%) was found in complex made by kneading method (OK1:1) in 1:1 molar ratio. All the complexes OSE1:1, OSE1:2, OK1:1, OK1:2 were found to be showing rough and porous surface morphology in SEM. Solubility as well as the dissolution of the complexes was found to be improved. Complex prepared by kneading method in 1:1 molar ratio (OK1:1) showed a marked improvement in percent drug release (88.94%) than that of pure drug (54.22%) at the end of 1 hour in dissolution study. FTIR, DSC and XRPD data confirmed the formation of inclusion complex. It was concluded that the complex made in 1:1 molar ratio (irrespective of the method) showed better solubility and dissolution profile as compared to complex made in 1:2 molar ratio.

POSSIBILITIES OF STUDYING THE LUNAR SOIL AND COMPARING THE COMPOSITIONS OF LUNAR AND TERRESTRIAL CLINOPYROXENES

2021 ◽  
Vol 27 (7) ◽  
pp. 6-17
Author(s):  
Z. Golitsyna ◽  
◽  
A. Kirdyashkin ◽  
Keyword(s):  
Lunar Surface ◽  
Experimental Studies ◽  
Compositional Analysis ◽  
Lunar Soil ◽  
The Moon ◽  
Initial Composition ◽  
Basic Model ◽  
Lunar Rocks ◽  
Celestial Bodies ◽  
Temperature And Pressure

The problem of compositional analysis of extraterrestrial crystalline rocks in the study of celestial bodies is considered. Since most of the bodies, terrestrial planets and their surrounding objects may contain clinopyroxenes, it is possible to study the temperature and pressure of rock formation in certain areas according to the state of these minerals, and the studies can be carried out identically to the geothermobarometry of Earth rocks. The paper presents the results of experimental studies of clinopyroxene compositions of the basic model system CaO-MgO-Al2O3-SiO2 in the pressure range of 12...30 kbar and temperatures of 1325...1650 °C, which can be assumed as conditions for the formation of lunar rocks. The development of the necessary experimental data obtained in terrestrial conditions will help in the future to conduct remote studies of the Moon and other celestial bodies without the need to deliver soil to Earth. The revealed clinopyroxenes can be analyzed with existing geothermometers and geobarometers obtained for different ranges of P-T conditions. The possibility of creating a new geothermobarometer based on the distribution of minals or cations in clinopyroxene specifically for lunar rocks is not excluded. The main features and possible instrumentation of the apparatus intended for the study of the lunar surface are described. The study of different areas of the lunar surface will determine where the country rocks are located most closely to the surface. Analysis of silicate components of the lunar rocks will make it possible to get closer to the solution to the problem of initial composition of the lunar mantle

Synthesis of a phosphorus–nitrogen-containing flame retardant and its application in epoxy resin

2018 ◽  
Vol 31 (2) ◽  
pp. 186-196 ◽  
Author(s):  
Shuang Yang ◽  
Yefa Hu ◽  
Qiaoxin Zhang
Keyword(s):  
Heat Release ◽  
Flame Retardant ◽  
Epoxy Resin ◽  
Heat Release Rate ◽  
Flame Retardancy ◽  
Release Rate ◽  
Epoxy Resins ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Cone Calorimeter Test

In this article, a phosphorus–nitrogen-containing flame retardant (DOPO-T) was successfully synthesized by nucleophilic substitution reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and cyanuric chloride. The chemical structure of DOPO-T was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance (NMR) and phosphorous-31 NMR, and elemental analysis. DOPO-T was then blended with diglycidyl ether of bisphenol-A to prepare flame-retardant epoxy resins. Thermal properties, flame retardancy, and combustion behavior of the cured epoxy resins were evaluated by differential scanning calorimetry, thermogravimetric analysis, limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The results indicated that the glass transition temperature ( Tg) and temperature at 5% weight loss of epoxy resin (EP)/DOPO-T thermosets were gradually decreased with the increasing content of DOPO-T. DOPO-T catalyzed the decomposition of EP matrix in advance. The flame-retardant performance of EP thermosets was significantly enhanced with the addition of DOPO-T. EP/DOPO-T-0.9 sample had an LOI value of 36.2% and achieved UL94 V-1 rating. In addition, the average of heat release rate, peak of heat release rate, average of effective heat of combustion, and total heat release (THR) of EP/DOPO-T-0.9 sample were decreased by 32%, 48%, 23%, and 31%, respectively, compared with the neat EP sample. Impressively, EP/DOPO-T thermosets acquired excellent flame retardancy under low loading of flame retardant.

Azomethine ether-based potential curing agent for epoxy resin (diglycidyl ether of bisphenol A): Synthesis and characterization

2020 ◽  
pp. 009524432092857
Author(s):  
Fozia Noreen ◽  
Ahtaram Bibi ◽  
Naila Khalid ◽  
Imran Ullah Khan
Keyword(s):  
Spectral Analysis ◽  
Bisphenol A ◽  
Light Emission ◽  
Condensation Reaction ◽  
Stokes Shift ◽  
Green Light ◽  
Diglycidyl Ether ◽  
Proton Nuclear Magnetic Resonance ◽  
Curing Agent ◽  
Scanning Calorimetry

Novel azomethine ether-based compounds (A: N-((4-(9-(4-(phenylimino)methyl)phenoxy)nonyloxy)benzylidene)bezenamine and B: N-((4-(9-(4-(p-hydroxyphenylimino)methyl)phenoxy)nonyloxy)benzylidene)-4-hydroxybenzenamine) were synthesized by condensation reaction of dialdehyde, 4,4-(1,9-nonandiyle)bis(oxy)dibenzaldehyde with aromatic amines. Structures of synthesized compounds were successfully characterized by Fourier transform infrared (FTIR), ultraviolet–visible, proton nuclear magnetic resonance imaging and photoluminescence (PL) spectroscopy. The PL spectral analysis revealed that emission maxima of compounds A and B are at 475 and 500 nm, respectively, indicate blue and green light emission with large Stokes shift range (Δ λ ST, 109–138 nm). Two series of polymers: one azomethine-based polymers (C1–C5) and other without azomethine (H1–H4) were prepared by curing diglycidyl ether of bisphenol A with a synthesized curing agent (B) and commercial curing agent, respectively, in various proportions. The structural characterization of the resulting polymers was carried out by FTIR spectral analysis. Thermal properties revealed that azomethine-based polymers (C1–C5) were thermally stable up to 400°C as compared to H1–H4. The glass transition temperature of the polymers, determined by differential scanning calorimetry, was in the range 121–123°C.

Sign in / Sign up

Export Citation Format

Share Document