Initial Extraction Stage Research Articles

Supercritical CO2 Conditions Affecting Extraction of Lipid and Cholesterol from Ground Beef

ABSTRACTGround beef was extracted by supercritical CO2 (SC‐CO2) with pressure ranging from 103‐310 bar at 30‐50°C. Higher pressure was needed to increase yield of extracted lipid. The profile of cholesterol content for the fractionated lipid extracted at 172 bar or 310 bar was generally lower in the initial stage of extraction and increased with CO2 used. DSC thermograms indicated that, depending upon extraction conditions, the distribution of lipid components of fractionated samples either shifted toward higher melting temperatures or concentrated those lipids melting between 5‐25°C.

Extraction of ginger rhizome: kinetic studies with supercritical carbon dioxide

SummaryThe rates of extraction of [6]‐gingerol from ground dried Jamaican ginger rhizomes were determined in supercritical carbon dioxide over the pressure range 128–197 bar (1850–2850 psi) and the temperature range 50–65°C. The CO2 densities varied from 0.415 to 0.775 g cm−3. First‐order plots showed two approximately linear sections with an initial intercept. The first linear section corresponded to a relatively fast initial extraction stage while the last 20% or so of the gingerol was extracted in the much slower subsequent stage. Reducing the ginger particle size by a factor of 3 increased the rate constant of the fast stage nine‐fold. Despite the low viscosity of the supercritical fluid, the rate constants of the fast stage were much smaller than in extractions with organic solvents. Only when the CO2 density was increased to 0.775 g cm−3 did the rate constant of the fast stage rise to a value comparable with, but still smaller than, those in organic solvents of similar density. The rate constants of the later slow extraction stage were also somewhat smaller than the corresponding values in organic solvents at 30°C.

Preliminary Studies on the Recovery of Bitumen from Nigerian Tar Sands: I. Beneficiation and Solvent Extraction

Abstract Solvent extraction of bitumen from Nigerian tar sands using toluene has been investigated. Pulverization of the tar sands followed by agglomeration in a mechanical shaker resulted in spherical agglomerates having higher bitumen contents than the mined tar sand. The extent of beneficiation was 4% and 19% for the high grade and low grade sands, respectively Temperature, agitation, and tar sand/solvent (S/L) ratios were found to be significant variables affecting the dissolution of bitumen from the sand. S/L ratio has the greatest effect on extraction efficiency. The rate of bitumen extraction, expressed as extractability η∗ showed great dependence on agitation. About 16- and 15-fold increases in extractability were obtained for SIL ratios of 1/20 and 1/5 respectively for a 2.8 fold increase in agitation At the initial stages of extraction, asphaltene content of the bitumen extracted at 50°C was less than that in the bitumen extracted at 25°C. This finding could have significant implications for the...

The measurement of insulin-like growth factor I: clinical applications and significance.

Of the somatomedins so far measured, the selective quantitation of insulin-like growth factor I (IGF-I) appears to have the greatest potential in clinical diagnosis. There have been two approaches to the development of immunoassay systems. One type uses antibodies raised against synthetic fragments of IGF-I which exhibit cross-reactivity with the whole hormone. Such assay systems may be adequate for measuring normal adult plasma IGF-I levels, but the potential for the higher sensitivity required for detecting sub-normal plasma levels in young children is apparent only in methods using antibodies raised against the complete hormone. IGF-I in plasma exists as part of a high molecular weight complex in which it is bound to carrier proteins. The binding proteins may interfere with plasma IGF-I measurements by radioligand assays. Direct analysis of untreated plasma samples is claimed to be possible using disequilibrium assay conditions but in order to maximise assay sensitivity it is necessary to employ an initial extraction stage in order to eliminate binding protein interference. Whether the measurement of plasma IGF-I can or should be used in addition to, or as a replacement for, plasma growth hormone (GH) measurement in the clinical assessment of growth disorders remains a controversial issue. Available evidence indicates that a single, random plasma IGF-I level provides an accurate reflection of GH secretion. Adequate discrimination between the elevated levels in acromegaly and normal reference values has been demonstrated. However, in the investigation of growth-retarded children available radioimmunoassay (RIA) methods have proved only partially successful because of the age-related nature of normal plasma IGF-I concentrations. Existing assays appear capable of identifying sub-normal plasma levels after the age of approximately 4 years. In younger subjects an improvement in assay sensitivity is required in order to establish with greater accuracy the relevant normal ranges. Improvements in the identification of the particular lesion responsible for retarded growth in a child can be achieved by measurement of both plasma GH and IGF-I concentrations. The predictive value of the acute plasma IGF-I response to single-dose GH therapy may identify patients who will respond to long-term GH therapy. Better, more informed decisions on subsequent treatment may therefore be made. Apart from GH control, several other factors influence circulating IGF-I levels. Nutritional status can be assessed through reference to IGF-I analysis, overall catabolic or anabolic processes being associated with decreasing or increasing plasma IGF-I levels respectively.

Diffusional resistance in extraction rate of copper with hydroxyoxime extractant.

The extraction of copper from sulphate media with a hydroxyoxime chelating extractant was carried out using a stirred transfer cell. Simple physical extraction studies of iodine or acetic acid were also carried out. From a comparison of the results, the extraction mechanism for copper was found to be expressed simply by a series of diffusional processes into the interface for the reactive species and the succeeding interfacial reaction, at least at the initial stages of extraction.

A Study on the Tilting of Teeth in Man

There is a fair amount of published literature on the positional changes of the residual teeth after substantial loss of the abjacent ones. But the majority of these studies are concerned with macroscopic observations of positional changes on the part of the residual teeth after several years of extraction by use of plaster models. They reflect difficulties in grasping accurately the positional changes of the residual teeth after extraction.Therefore, the author and his associates earlier reported on our measurement. method and measurement apparatus. In the present study, the author was concerned with the positional changes is a selected sample of 10 Japanese dental students by an application of the above measurement method and apparatus. With these subjects, efforts were made to establish chronologically the changes of the residual teeth after extraction of the mandibular first molar on the right side.As a result, the author arrived at the following findings: 1. Throughout the measurement period, all the subjects were found to have suffered from some kind of positional changes in the second premolar and second molar on the extracted side.With the exception of 1 subject, the remaining 9 subjects suffered from the positional change in the first premolar.2. With the residual teeth from the mandibular right canine to left second molar, there were found no positional changes in all the subjects.3. With the right first, second premolars and second molar in which the positional changes were found, the amount of change was the largest in the second molar in common with all the subjects.4. In terms of dental regions where the positional changes were found, there was a statistical difference between the time passage after extraction and the amount of changes except for the first premolar in 1 subject.5. There were observed two different patterns in the positional change of the second molar on the extracted side. One pattern was that the amount of change was noticeably large in the initial stage of extraction, the change becoming smaller in proportion to the passage of time.The other pattern, on the other hand, showed an opposite tendency.6. In terms of the time passage after extraction and the amount of positional change in all the subjects, there was observed a fairly high correlation between the first, second premolars and the second molar in these items.7. Based on the amount of positional changes obtained from all the subjects, the degree of positional change of the second molar was approximately 10 times as large as that of the first premolar, and approximately 7.5 times that of the second premolar.8. Concerning the time-point when positional changes of the adjacent teeth would occur after dental extraction, the change took place comparatively soon in the second molar and anywhere from 15 days to one month in the second premolar. As regards the first premolar, on the other hand, the positional change occurred after that of the second premolar took place.

A Study on the Tilting of Teeth in Man

There is a fair amount of published literature on the positional changes of the residual teeth after substantial loss of the abjacent ones. But the majority of these studies are concerned with macroscopic observations of positional changes on the part of the residual teeth after several years of extraction by use of plaster models. They reflect difficulties in grasping accurately the positional changes of the residual teeth after extraction.Therefore, the author and his associates earlier reported on our measurement. method and measurement apparatus. In the present study, the author was concerned with the positional changes is a selected sample of 10 Japanese dental students by an application of the above measurement method and apparatus. With these subjects, efforts were made to establish chronologically the changes of the residual teeth after extraction of the mandibular first molar on the right side.As a result, the author arrived at the following findings: 1. Throughout the measurement period, all the subjects were found to have suffered from some kind of positional changes in the second premolar and second molar on the extracted side.With the exception of 1 subject, the remaining 9 subjects suffered from the positional change in the first premolar.2. With the residual teeth from the mandibular right canine to left second molar, there were found no positional changes in all the subjects.3. With the right first, second premolars and second molar in which the positional changes were found, the amount of change was the largest in the second molar in common with all the subjects.4. In terms of dental regions where the positional changes were found, there was a statistical difference between the time passage after extraction and the amount of changes except for the first premolar in 1 subject.5. There were observed two different patterns in the positional change of the second molar on the extracted side. One pattern was that the amount of change was noticeably large in the initial stage of extraction, the change becoming smaller in proportion to the passage of time.The other pattern, on the other hand, showed an opposite tendency.6. In terms of the time passage after extraction and the amount of positional change in all the subjects, there was observed a fairly high correlation between the first, second premolars and the second molar in these items.7. Based on the amount of positional changes obtained from all the subjects, the degree of positional change of the second molar was approximately 10 times as large as that of the first premolar, and approximately 7.5 times that of the second premolar.8. Concerning the time-point when positional changes of the adjacent teeth would occur after dental extraction, the change took place comparatively soon in the second molar and anywhere from 15 days to one month in the second premolar. As regards the first premolar, on the other hand, the positional change occurred after that of the second premolar took place.