scholarly journals The Asphaltene Fraction – Demystified

2019 ◽  
Vol 2 (4) ◽  
Keyword(s):  
Molecular Weight ◽  
Melting Point ◽  
Crude Oil ◽  
Chemical Constituents ◽  
Structural Type ◽  
Structural Features ◽  
Behavioral Characteristics ◽  
Molecular Models ◽  
Asphaltene Fraction ◽  
Average Structures

The asphaltene constituents of crude oil are the highest molecular weight heaviest and most polar constituents in the oil and the fraction is isolated a dark brown to black friable solids that have no definite melting point and usually foam and swell on heating to leave a carbonaceous residue. The fraction is obtained from crude oil by the addition of a hydrocarbon liquid (such as n-pentane or n-heptane). Any molecular models derived for asphaltene constituents must be in keeping with behavioral characteristics. Efforts have been (and continue to be) made without justification to describe the asphaltene fraction in terms of a single, representative asphaltene molecule or molecules incorporating, in the correct proportions, all of the chemical constituents known to be present in a given asphaltenic matrix. Obviously, the chemistry and structural features of the constituents of crude oil asphaltene fractions will be dictated by the distribution of functional and structural type that occur in the fraction. This makes the representation of the structure and functionality of the constituents by so-called average structures very difficult (if not, impossible) to conceive.

scholarly journals Effect of the dispersion of the chromophore on the optical performances of polarizers from polyethylene and 5”-thio- (3-butyl)nonyl-2,2’:5’,2”-terthiophene

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Andrea Pucci ◽  
Letizia Moretto ◽  
Giacomo Ruggeri ◽  
Francesco Ciardelli
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Melting Point ◽  
Drawing Ratio ◽  
Scanning Calorimetry ◽  
Affine Deformation ◽  
Ultra High Molecular Weight ◽  
Scanning Electron

AbstractA new polyethylene-compatible terthiophene chromophore, 5”-thio-(3- butyl)nonyl-2,2’:5’,2”-terthiophene, with melting point lower than 0°C was prepared and used for linear polarizers based on ultra-high-molecular-weight polyethylene (UHMWPE). Differential scanning calorimetry and scanning electron microscopy indicate that the new chromophore is dispersed uniformly in films of UHMWPE obtained by casting from solution. The films show excellent dichroic properties (dichroic ratio 30) at rather low drawing ratio (≈ 20) . Moreover, qualitative agreement is observed with the Ward pseudo-affine deformation scheme.

Computational Study for Molecular Properties of Some of the Isolated Chemicals from Leaves Extract of Guiera Senegalensis as Aluminium Corrosion Inhibitor

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
A. M. Ayuba ◽  
◽  
M. Abubakar ◽  
Keyword(s):  
Molecular Dynamics ◽  
Quantum Chemical ◽  
Energy Gap ◽  
Computational Study ◽  
Physical Adsorption ◽  
Chemical Constituents ◽  
Molecular Size ◽  
Structural Features ◽  
Inhibitor Molecule ◽  
Fukui Indices

The present work describes the computational methods for the corrosion inhibition of aluminium using three selected chemical constituents (5-methyldihydroflavasperone, 5-methylflavasperone and methoxylated naphthyl butanone) reportedly obtained from the leaves extract of Guirea senegalensis. Quantum chemical calculations including EHOMO, ELUMO, energy gap (ΔE), electronegativity (χ), global hardness (η) and fraction of electrons transfer from the inhibitor molecule to the aluminium surface (ΔN) were calculated. The local reactive sites through Fukui indices which explain the effect of structural features of these components in relation to electrophilic and nucleophilic point of attack were evaluated. The similarities in quantum chemical parameters for the compounds obtained revealed that the adsorption strengths of the molecules will be mostly determined by molecular size rather than electronic structure parameters. Fukui indices showed that the point of interaction of inhibitor molecule with the Al(l10) surface were through aromatic carbon atom rich in pi-electrons and oxygen atom of the alkanone functional group in the inhibitor molecules. Molecular dynamics simulations describing the adsorption behavior of the inhibitor molecule on Al(110) surface through Forcite quench molecular dynamics were carried out. The compounds were found to all obey the mechanism of physical adsorption because of their relatively low adsorption energies.

Characterization of two Salmonella newport bacteriophages

1979 ◽  
Vol 25 (9) ◽  
pp. 1063-1072 ◽  
Author(s):  
N. Moazamie ◽  
H.-W. Ackermann ◽  
M. R. V. Murthy
Keyword(s):  
Molecular Weight ◽  
Melting Point ◽  
Acid Hydrolysis ◽  
Phage Particle ◽  
Size Classes ◽  
Salmonella Newport ◽  
Double Stranded Dna

Salmonella newport phages 16–19 and 7–11 have very long heads and are members of two rare and so far little-known phage groups. Both produce various morphological aberrations. Preparations of phage 7–11 contain numerous polyheads and about 0.4% short heads belonging to nine size classes. In addition, one giant phage particle was observed. The head of phage 7–11 seems to be an icosahedron which became elongated by adding successive rows of subunits. Phages 16–19 and 7–11 have buoyant densities in CsCl of 1.43 and 1.48 g/mL and particle weights of 103 and 204 × 106 respectively. Both viruses contain double-stranded DNA, internal proteins, and sugars. Phage 16–19 contains 46.5% DNA of 35 × 106 molecular weight, and glucose. Phage 7–11 contains 47.5% DNA of 108 × 106 molecular weight, and mannose. Base compositions of phage and S. newport DNAs were determined from buoyant densities, melting point, and acid hydrolysis. Phage 16–19 contains 5.4% 5-methylcytosine.

scholarly journals Evaporation of Heavy Crude Oil in Soil

2021 ◽  
pp. 59-62
Author(s):  
Etini Etefia ◽  
L. O. Odokuma
Keyword(s):  
Molecular Weight ◽  
Crude Oil ◽  
Pour Point ◽  
Terrestrial Ecosystem ◽  
Heavy Crude Oil ◽  
Percentage Reduction ◽  
Oil Spillage ◽  
Heavy Crude ◽  
Rate Of Evaporation ◽  
Oil Density

Heavy crude oil spillage on soil threatens productivity and affects the natural biota of the ecosystem. Evaporation is an important parameter increases crude oil density, viscosity and fraction of lower molecular weight substances which reduce its infiltration into the soil and groundwater. The evaporation of heavy crude oil showed API of 21.5, viscosity of 15mm2/s, density 0.8952 g/cm3, pour point of 11.37. The crude oil was exposed to solar radiation for 35 days. The percentage reduction in mass of the crude oil and temperature on five day interval showed 8.22(38OC) on day 0, on day 5 was 8.13(34oC), on day 10 was 5.92(39oC), on day 15 was 5.38(39oC), on day 20 was 3.16(37oC), on day 25 was 2.94(31oC), on day 20 was 2.56 (41oC) and on day 35 was 1.79(38oC). The lighter molecules evaporated first leaving the heavier molecules behind causing a reduction in the rate of evaporation with time. This analysis will be provide insight to modelling oil spill in terrestrial ecosystem.

Isolation and characterization of some novel genes of the apolipoprotein A-I family in Japanese eel, Anguilla japonica

2011 ◽  
Vol 6 (4) ◽  
pp. 545-557 ◽  
Author(s):  
Malay Choudhury ◽  
Takahiro Oku ◽  
Shoji Yamada ◽  
Masaharu Komatsu ◽  
Keita Kudoh ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Consensus Sequence ◽  
Structural Features ◽  
Lipid Binding ◽  
Japanese Eel ◽  
Amino Acid Sequences ◽  
Novel Genes ◽  
Isolation And Characterization

AbstractApolipoproteins such as apolipoprotein (apo) A-I, apoA-IV, and apoE are lipid binding proteins synthesized mainly in the liver and the intestine and play an important role in the transfer of exogenous or endogenous lipids through the circulatory system. To investigate the mechanism of lipid transport in fish, we have isolated some novel genes of the apoA-I family, apoIA-I (apoA-I isoform) 1–11, from Japanese eel by PCR amplification. Some of the isolated genes of apoIA-I corresponded to 28kDa-1 cDNAs which had already been deposited into the database and encoded an apolipoprotein with molecular weight of 28 kDa in the LDL, whereas others seemed to be novel genes. The structural organization of all apoIA-Is consisted of four exons separated by three introns. ApoIA-I10 had a total length of 3232 bp, whereas other genes except for apoIA-I9 ranged from 1280 to 1441 bp. The sequences of apoIA-Is at the exon-intron junctions were mostly consistent with the consensus sequence (GT/AG) at exon-intron boundaries, whereas the sequences of 3′ splice acceptor in intron 1 of apoIA-I1-7 were (AC) but not (AG). The deduced amino acid sequences of all apoIA-Is contained a putative signal peptide and a propeptide of 17 and 5 amino acid residues, respectively. The mature proteins of apoIA-I1-3, 7, and 8 consisted of 237 amino acids, whereas those of apoIA-I4-6 consisted of 239 amino acids. The mature apoIA-I10 sequence showed 65% identity to amino acid sequence of apoIA-I11 which was associated with an apolipoprotein with molecular weight of 23 kDa in the VLDL. All these mature apoIA-I sequences satisfied the common structural features depicted for the exchangeable apolipoproteins such as apoA-I, apoA-IV, and apoE but apoIA-I11 lacked internal repeats 7, 8, and 9 when compared with other members of apoA-I family. Phylogenetic analysis showed that these novel apoIA-Is isolated from Japanese eel were much closer to apoA-I than apoA-IV and apoE, suggesting new members of the apoA-I family.

A COMPARISON OF TOPICAL AND SUBCUTANEOUS METHODS OF ADMINISTRATION OF SIXTEEN OESTROGENS

1963 ◽  
Vol 26 (3) ◽  
pp. 317-329 ◽  
Author(s):  
C. F. MORGAN
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Melting Point ◽  
Uterine Weight ◽  
Rank Orders ◽  
Target Organs ◽  
Structure And Activity ◽  
Response Variables

SUMMARY This study showed that the application of hormones directly on the surface of the skin will result in uterine and vaginal weight stimulation, at times equal to and sometimes more effective than effects obtained by s.c. injection of the same hormones in the same concentration and over the same length of time. This effect was apparent, using sixteen different oestrogens. It was also shown that the uterine weight response is more sensitive and discriminatory in detecting differences between the potencies of oestrogens than is the vaginal weight response. The rank orders by both response variables, whether by topical or s.c. administration, were similar. It was shown statistically that the differences in potency of the sixteen oestrogens tested in this study are related more to certain molecular structure than to difference in solubility, molecular weight, or melting point. It was postulated that the potency of the oestrogens was related to their molecular structure and activity within the target organs.

scholarly journals Terpenoids and Sterols from Some Japanese Mushrooms

2014 ◽  
Vol 9 (3) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Yasunori Yaoita ◽  
Masao Kikuchi ◽  
Koichi Machida
Keyword(s):  
Lentinula Edodes ◽  
Chemical Constituents ◽  
Structural Features ◽  
Tricholoma Matsutake ◽  
Pholiota Nameko ◽  
The Past ◽  
Polyporus Umbellatus ◽  
Hericium Erinaceum ◽  
New Compounds ◽  
Hypsizigus Marmoreus

Over the past twenty years, our research group has been studying the chemical constituents of mushrooms. From nineteen species, namely, Amanita virgineoides Bas (Amanitaceae), Daedaleopsis tricolor (Bull.: Fr.) Bond. et Sing. (Polyporaceae), Grifola frondosa (Fr.) S. F. Gray (Polyporaceae), Hericium erinaceum (Bull.: Fr.) Pers. (Hericiaceae), Hypsizigus marmoreus (Peck) Bigelow (Tricholomataceae), Lactarius piperatus (Scop.: Fr.) S. F. Gray (Russulaceae), Lentinula edodes (Berk.) Sing. (Pleurotaceae), Lyophyllyum connatum (Schum.: Fr.) Sing. (Tricholomataceae), Naematoloma sublateritium (Fr.) Karst. (Strophariaceae), Ompharia lapidescens Schroeter (Polyporaceae), Panellus serotinus (Pers.: Fr.) Kuhn. (Tricholomataceae), Pholiota nameko (T. Ito) S. Ito et Imai in Imai (Strophariaceae), Pleurotus eringii (DC.: Fr.) Quel. (Pleurotaceae), Polyporus umbellatus Fries (Polyporaceae), Russula delica Fr. (Russulaceae), Russula sanguinea (Bull.) Fr. (Russulaceae), Sarcodon aspratus (Berk.) S. Ito (Thelephoraceae), Tricholoma matsutake (S. Ito et Imai) Sing. (Tricholomataceae), and Tricholoma portentosum (Fr.) Quel. (Tricholomataceae), we isolated eight new sesquiterpenoids, six new meroterpenoids, three new triterpenoids, and twenty eight new sterols. In this review, structural features of these new compounds are discussed.

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