Two-stage pyrolysis of heavy oils. 3. Pyrolysis of tar-sand bitumens. Relation between ethylene yield and structural characteristics of heavy oils

Thermal cracking of tar-sand bitumens has been carried out using a two-stage pyrolysis reactor with temperature zones of 440°C and 750–800°C, respectively. Feedstocks were pyrolysed in the first stage into cracked oils, which were carried to the second stage for subsequent pyrolysis. Only 12–14 wt% of ethylene was obtained from tar-sand bitumens at the residence time of 1.2 s in the second stage, although 27 and 16 wt% were obtained from Taching and Iranian heavy vacuum residues, respectively. The tar-sand bitumens contain shorter paraffinic straight-chains and have more branched molecules than the vacuum residues of petroleum. A straight-chain paraffin index is proposed, with which a good correlation was obtained between ethylene yield and the fraction of straight-chain paraffin carbons in the heavy oil.     

Sterol composition of 19 vegetable oils

The unsaponifiables from 19 vegetable oils were divided into a sterol and three other fractions by thin-layer chromatography. All except olive and palm kernel oils gave the sterol fraction in a large quantity. Compositions of the sterol fractions were determined by gas liquid chromatography. Identification of each sterol was carried out by gas liquid chromatography and combined gas chromatograph-mass spectrometry. Campesterol, stigmasterol and β-sitosterol were present in all oils, and a minor amount of cholesterol in majority of the oils. Brassicasterol occurrence was widespread but its content was extremely small in oils other than rapeseed oil. Other sterols, presumably δ⁷-stigmastenol and δ⁵- and δ⁷-avenasterol were detected in most of the oils.     

Reduction of fatty acid hydroperoxides by human parotid saliva

Arachidonic acid hydroperoxide (15-hydroperoxyeicosatetraenoic acid; 15-HPETE) was introduced into human parotid saliva and incubated at 37°C. Straight phase high-performance liquid chromatography analysis of the reaction mixture showed that 15-HPETE was detoxified to its reduced form, 15-hydroxyeicosatetraenoic acid, in the presence of glutathione. Therefore, it is concluded that human parotid saliva possesses fatty acid hydroperoxide-reducing ability. However, its effectiveness was found to be lower than that of blood plasma.     

Investigation of Ozone Loss Rate Influenced by the Surface Material of a Discharge Chamber

Decay characteristics of ozone concentration in oxygen in a chamber with three types of wall material (stainless steel, copper, and aluminum) are measured using the 254 nm photoabsorption method. Effective lifetimes of ozone are estimated from decay curves of ozone concentration. These values depend on the wall material: They are largest for stainless steel and smallest for aluminum. The relationship between effective lifetime and gas pressure is investigated precisely to determine three values. The equivalent diffusion coefficient of ozone in oxygen and the reflection coefficient of ozone at the wall correspond to the loss rate of ozone at the wall. The collisional loss (quenching) rate coefficient of ozone in oxygen is also determined.     

Triterpene alcohols and sterols of Spanish olive oil

Nine Spanish olive oils, including three each of virgin (pressed oil), refined virgin, and B-residue (solvent-extracted pomace oil) oils from different commercial sources, have been analyzed for their unsaponifiable matter (USM). Four sterolic fractions separated from the oils have been analyzed by preparative thin-layer chromatography (TLC); these fractions are triterpene alcohols, 4-methylsterols, sterols and triterpene dialcohols. The compositions of the four sterolic fractions were determined as their acetates by gas-liquid chromatography (GLC) on an OV-17 glass capillary column. Identification of each component was carried out by argentation TLC, GLC and combined gas chromatography-mass spectrometry (GC-MS); 44 components were identified, of which four: 24-methylene-31-nor-9(11)-lanostenol, 24-methyl-31-nor-E-23-dehydrocycloartanol, 24-ethyl-E-23-dehydrolophenol and 5,E-23-stigmastadienol, were considered to be new sterols from natural sources. Several characteristics, including the content of triteterpene dialcohols in the USM and that of C-24(28) unsaturated sterols in each of the four sterolic fractions, which can be used to distinguish between virgin and B-residue olive oils, were observed.     

Hydrophobic effects on protein/nucleic acid interaction: enhancement of substrate binding by mutating tyrosine 45 to tryptophan in ribonuclease Tl

Hydrophobic effects on binding of ribonuclease Tl to guaninebases of several ribonucleotides have been proved by mutatinga hydrophobic residue at the recognition site and by measuringthe effect on binding. Mutation of a hydrophobic surface residueto a more hydrophobic residue (Tyr45 – Trp) enhances thebinding to ribonucleotides, including mononucleotide inhibitorand product, and a synthetic substrate-analog trinudeotide aswell as the binding to dinucleotide substrates and RNA. Enhancementson binding to non-substrate ribonucleotides by the mutationhave been observed with free energy changes ranging from –2.2 to – 3 .9 kJ/mol. These changes are in good agreementwith that of substrate binding, –2.3 kJ/mol, which iscalculated from Michaelis constants obtained from kinetic studies.It is shown, by comparing the observed and calculated changesin binding free energy with differences in the observed transferfree energy changes of the amino acid side chains from organicsolvents to water, that the enhancement observed on guaninebinding comes from the difference in the hydrophobic effectsof the side chains of tyrosine and tryptophan. Furthermore,a linear relationship between nucleolytic activities and hydrophobicityof the residues (Ala, Phe, Tyr, Trp) at position 45 is observed.The mutation could not change substantially the base specificityof RNase Tl, which exhibits a prime requirement for guaninebases of substrates.     

Mechanisms of aerosol deposition in a nasal model

Total and regional aerosol deposition were investigated in a model of a normal human nasal airway. Contributions of fluid turbulence and particle inertia were evaluated using monodisperse aerosols. At fixed turbulent flow conditions, deposition percentage increased with particle size greater than 1 μm, suggesting that turbulent inertial deposition is a primary mechanism.

With same size aerosol, deposition increased with increasing fluid turbulence but its contribution was less with larger size aerosol. Turbulent diffusion was the dominant transport mechanism for particles less than 1 μm, where deposition decreased with particle size. Two major deposition sites were visualized with radio-aerosol in the anterior region of the nasal airway. One is close to the ostium internum where turbulent eddies are well developed, and the other is the anterior region of the middle turbinate where direction of airflow changes from upward to horizontal.     

Carbon-13 NMR spectroscopic analysis of 24-methyl-Δ5,22-sterols in rape and mustard seed oils

24-Methylcholesta-5,E-22-dien-3β-ol (C₂₈ Δ^5,22-sterol) was separated from the unsaponifiable matters of the following eight seed oils of Brassica species:Brassica campestris (candle I and II and torch),B. napus (tower and midas),B. juncea (brown and oriental mustards), andB. alba (yellow mustard). The configuration at C-24 methyl group of the respective sterols was evaluated by¹³C NMR spectroscopy. All the C₂₈ Δ^5,22-sterols in the Brassica seed oils were found to contain the C-24 epimer of brassicasterol,trans-22-dehydrocampesterol, in the range of ca. 10–30%.     

Sterols,methylsterols, and triterpene alcohols in threeTheaceae and some other vegetable oils

The unsaponifiables from threeTheaceae (Camellia japonica L.,Camellia Sasanqua Thunb., andThea sinensis L.) oils and alfalfa, garden balsam, and spinach seed oils and shea fat were separated into four fractions: sterols, 4-methylsterols, triterpene alcohols, and less polar compounds by thin layer chromatography. While the sterol fraction was the major one for the unsaponifiables from alfalfa and spinach seed oils, the triterpene alcohol fraction was predominant for the unsaponifiables from all other oils. The sterol, 4-methylsterol, and triterpene alcohol fractions were analyzed by gas chromatography. All the sterol fractions were alike in their compositions, consisting exclusively of Δ⁷-sterols, such as α-spinasterol and Δ⁷-stigmastenol as predominant components together with Δ⁷-avenasterol and 24-methylcholest-7-enol. Obtusifoliol, gramisterol (occasionally accompanied with cycloeucalenol), and citrostadienol, together with several other unidentified components, were found in the 4-methylsterol fractions from all of the oils except shea fat. The 4-methylsterol fraction from shea fat showed a characteristic composition containing a large proportion of unidentified components which had relative retention time greater than that of citrostadienol, while no citrostadienol was detected. β-Amyrin, lupeol, and butyospermol were major components of the triterpene alcohol fractions from most of the oils, but the fraction from spinach seed oil contained cycloartenol and 24-methylene-cycloartanol as predominant components. There is a close similarity in the compositions of unsaponifiables (sterols, 4-methylsterols, and triterpene alcohols) of the threeTheaceae oils. Two sterols, α-spinasterol and Δ⁷-stigmastenol, and five triterpene alcohols were isolated from tea seed oil. Moreover, five unidentified components beside parkeol, butyrospermol, α-amyrin, and lupeol were isolated from the triterpene alcohol fraction of shea fat.     

Thermodynamic investigations of liquid Bi-Na and Sn-Na alloys by coulometric titration using β″-alumina

The following double galvanic cell was assembled and the thermodynamic properties of liquid Bi-Na and Sn-Na alloys, and the ion selectivity of -alumina during coulometric titration, were investigated. Mo, Na(I)¦-alumina¦M-Na(I), Mo [I] M-Na(I)¦-alumina¦Au + Au₂Na, Mo [II] (M = Bi or Sn) where M-Na(1) and Au + Au₂Na were used as the common electrode and reference electrode, respectively. Sodium was coulometrically titrated through the -alumina electrolyte of cell I both ways, and the EMFs were measured. It was found that no ion-exchange reaction occurs between the liquid alloys and the -alumina, and only Na was transferred in the -alumina during coulometric titrations. The thermodynamic properties of liquid Sn-Na and Bi-Na alloys were found to be in agreement with the literature.