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At least 19 recordsLinked to original sources
PubMed1993

Studies on a new cross-axis coil planet centrifuge for performing counter-current chromatography. II. Path and acceleration of coils and comparison with type J coil planet centrifuge.

A comprehensive approach is introduced using parametric equations to describe the motion induced by type J and cross-axis type coil planet centrifuges. The plots of a line parallel to the coil axis are given. The centrifugal forces are then analyzed in two ways. Three-dimensional graphs show their geometry and the relative intensity of the lateral component is compared to that of the perpendicular component. This allowed a better understanding of the differences in paths and acceleration fields induced by the two types of counter-current chromatography devices.

Acceleration↗
PubMed1996

Planet Within a Planet: Rotation of the Inner Core of Earth

The time dependence of the orientation of Earth's inner core relative to the mantle was determined using a recently discovered 10-degree tilt in the axis of symmetry of the inner core's seismic-velocity anisotropy. Two methods of analyzing travel-time variations for rays traversing the inner core, on the basis of 29 years of data from the International Seismological Centre (1964-1992), reveal that the inner core appears to rotate about 3 degrees per year faster than the mantle. An anomalous variation in inner-core orientation from 1969 to 1973 coincides in time with a sudden change ("jerk") in the geomagnetic field.

Journal Article↗
PubMedDate not supplied

Gravitational scattering as a possible origin for giant planets at small stellar distances.

The recent discoveries of massive planetary companions orbiting several solar-type stars pose a conundrum. Conventional models for the formation of giant planets (such as Jupiter and Saturn) place such objects at distances of several astronomical units from the parent star, whereas all but one of the new objects are on orbits well inside 1 AU; these planets must therefore have originated at larger distances and subsequently migrated inwards. One suggested migration mechanism invokes tidal interactions between the planet and the evolving circumstellar disk. Such a mechanism results in planets with small, essentially circular orbits, which appears to be the case for many of the new planets. But two of the objects have substantial orbital eccentricities, which are difficult to reconcile with a tidal-linkage model. Here we describe an alternative model for planetary migration that can account for these large orbital eccentricities. If a system of three or more giant planets form about a star, their orbits may become unstable as they gain mass by accreting gas from the circumstellar disk; subsequent gravitational encounters among these planets can eject one from the system while placing the others into highly eccentric orbits both closer and farther from the star.

Evolution, Planetary↗
PubMed1995

Inhibition of giant-planet formation by rapid gas depletion around young stars.

Although stars form from clouds of gas and dust, there are insignificant amounts of gas around ordinary (Sun-like) stars. This suggests that hydrogen and helium, the primary constituents of planets such as Jupiter and Saturn, are not easily retained in orbit as a star matures. The gas-giant planets in the Solar System must therefore have formed rapidly. Models of their formation generally suggest that a solid core formed in < or = 10(6) yr, followed by the accretion of the massive gaseous envelope in approximately 10(7) yr (refs 1-5). But how and when the gas of the solar nebula dissipated, and how this compares with the predicted timescale of gas-giant formation, remains unclear, in part because direct observations of circumstellar gas have been made only for stars either younger or older than the critical range of 10(6)-10(7) yr (refs 8-15). Here we report observations of the molecular gas surrounding 20 stars whose ages are likely to be in this range. The gas dissipates rapidly; after a few million years the mass remaining is typically much less than the mass of Jupiter. Thus, if gas-giant planets are common in the Galaxy, they must form even more quickly than present models suggest.

Extraterrestrial Environment↗
PubMed1997

Habitable moons around extrasolar giant planets.

Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere.

Exobiology↗
PubMed1975

High pH ammonia toxicity, and the search for life on the Jovian planets.

Jovian plants have enviroments apparently suitable for the evolution of life, but nevertheless, present severe challenges to organisms. One such challenge arises from the presence of ammonia. Ammonia is an efficient biocide, its effect being dependent on pH as well as on concentration. The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural enviornments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, survival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is, nevertheless, two to three orders of magnitude longer than for E. coli. Our data support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

Ammonia↗
PubMed1989

Hemolysis by aliphatic alcohols and saponin measured by the coil planet centrifugation method.

Using the coil planet centrifugation method, the mechanism of hemolysis by alcohols and saponin was investigated. With this technique, erythrocytes are introduced into a gradient of hemolytic agents in saline, which is prepared in a long coiled polyethylene tube. The tube is centrifuged so that the cells move from a low to a high concentration of hemolytic agent. When the cells lyse, they release hemoglobin which remains stationary, and therefore hemolytic potency can be determined spectrophotometrically by the distance the cells move before lysing. We found that alcohols caused hemolysis at a particular concentration, whereas saponin-induced hemolysis was dependent on the amount of saponin accumulated in the environment of the cell. In addition, alcohols with longer carbon chains were more potent hemolytic agents than those with shorter chains, but each additional carbon group produced less of an increase in hemolysis per mole of alcohol. This chain-length dependency is consistent with a previous study on in vivo alcohol-induced hemolysis. The coil planet centrifugation method is also adaptable to comparative studies on the mechanism of other types of hemolysis, such as immune or drug-induced lysis, and to toxicological studies.

Alcohols↗
PubMed1984

Continuous extraction of urinary anthracycline antitumor antibiotics with the horizontal flow-through coil planet centrifuge.

Extraction of doxorubicin (adriamycin) and daunorubicin and their metabolites from human urine was attempted utilizing the horizontal flow-through coil planet centrifuge. Partition coefficients of the drugs for various combinations of non-aqueous phases and aqueous salt solutions were determined. Optimal coefficients for adriamycin and daunorubicin were achieved with n-butanol-0.3 M disodium hydrogen phosphate. Extraction efficiencies of the drugs from human urine comparable to those obtained by standard resin column techniques could be realized by employing the n-butanol-urine (containing 0.3 M disodium hydrogen phosphate) system in the coil planet centrifuge, at flow-rates of 500-600 ml/h, and at 650 rpm revolutional speed. Small quantities of drugs and metabolites could be continuously concentrated into small volumes of the n-butanol phase from large volumes of salted urine. The versatility of the technique was demonstrated by its application to extraction of aclacinomycin A, a novel anthracycline antitumor agent, and its metabolites from human urine.

1-Butanol↗
PubMed1975

Coil planet centrifugation and its application to the observation of altered membrane properties of erythrocytes in hepatobiliary disorders.

A coil planet centrifuge (CPC) is an apparatus aiming to obtain a centrifugal force exerting on particles suspended in a fluid in a coiled polyethylene tube (coil) which makes self-rotation around its axis and revolution around the principal axis simultaneously. If a linear osmotic gradient is prepared in the coil and a small amount of blood is applied to it and subjected to centrifugation, one is able to observe the membrane properties of erythrocytes in terms of the shift of hemolysis band appearing in the coil with high accuracy and precision. Coil planet centrifugation was applied to the observation of altered membrane properties of erythrocytes in hepatobiliary diseases. Remarkable shifts of end-point of the hemolysis band going in parallel with the severity of damage were visualized. Study as to its cause revealed that increased free cholesterol content of erythrocyte membrane which was the result of plasma cholesterol Esterstürz due to inhibition of lecithin-cholesterol acyltransferase by stagnant bile acids was responsible for this phenomenon. Elevation of serum bile acid concentration and increased serum leucine-aminopeptidase were closely correlated to the shift of hemolysis end-point toward the low osmolal side. CPC may be useful for detection and chasing the clinical course of patients with hepatobiliary disorders.

Acute Disease↗
PubMed1980

Coil planet centrifuge - a new method for measurement of osmotic fragility of erythrocytes and its application in alcohol liver injuries.

The present study was designed to examine the osmotic resistance of erythrocytes measured by a new method-Coil Planet Centrifuge under the glutaraldehyde incubation, and to determine free cholesterol and adenine nucleotide contents of glutaraldehyde-treated erythrocytes compared with that of control erythrocytes. Glutaraldehyde increased the osmotic resistance of erythrocytes. Hemolysis end point of glutaraldehyde-treated erythrocytes shifted to hypo-osmolar side after 2.5 h hours incubation (p less than 0.001). Free cholesterol content of erythrocytes was not changed by the addition of glutaraldehyde, however, ATP content significantly increased when compared with controls (p less than 0.001). Moreover, the osmotic resistance of erythrocytes in 55 patients with alcoholic liver injuries and the relation between the disease were examined by Coil Planet Centrifuge. Hemolysis end point shifted to hypo-osmolar side in the patients, and our results suggest that the increase in osmotic resistance is partly responsible for the increase in the rigidity of erythrocytes. This new method was also helpful in evaluation in the clinical course of alcoholic liver injuries.

Adenosine Triphosphate↗
PubMed1996

The transfer of viable microorganisms between planets.

There is increasing acceptance that catastrophic cosmic impacts have played an important role in shaping the history of terrestrial life. Large asteroid and cometary impacts are also capable of displacing substantial quantities of planetary surface material into space. The discovery of Martian rocks on Earth suggests that viable microorganisms within such ejecta could be exchanged between planets. If this conjecture is correct, it will have profound implications for the origin and evolution of life in the solar system.

Archaea↗
PubMed1995

Condensation of methane, ammonia, and water and the inhibition of convection in giant planets.

The condensation of chemical species of high molecular mass such as methane, ammonia, and water can inhibit convection in the hydrogen-helium atmospheres of the giant planets. Convection is inhibited in Uranus and Neptune when methane reaches an abundance of about 15 times the solar value and in Jupiter and Saturn if the abundance of water is more than about five times the solar value. The temperature gradient consequently becomes superadiabatic, which is observed in temperature profiles inferred from radio-occultation measurements. The planetary heat flux is then likely to be transported by another mechanism, possibly radiation in Uranus, or diffusive convection.

Ammonia↗
PubMed1981

Studies on osmotic fragility of red blood cells determined with a coil planet centrifuge for workers occupationally exposed to lead.

In order to clarify the relationship between lead exposure level and osmotic fragility of red blood cells determined by the coil planet centrifuge method, several clinical laboratory examinations were performed on 27 male workers employed in a scrap lead refining factory using as controls 40 male workers employed in railway construction. The examinations included measurement of red blood cell and reticulocyte counts, hematocrit, MCV, blood and urine lead concentrations, urine coproporphyrin, and urine delta-aminolevulinic acid. The results were: 1. Osmotic fragility of red blood cells was lower in lead workers at all three hemolytic points compared with the controls. Significant difference was observed in hemolysis of the maximum point (P less than 0.05). 2. The red blood cell and reticulocyte counts, hematocrit value and MCV of the lead workers were not significantly different from those of the controls. Values for blood and urine lead, coproporphyrin, and delta-aminolevulinic acid of the lead workers were much higher than those of the controls (P less than 0.01). 3. In lead workers, close relationships between the osmotic fragility and these laboratory findings were observed: blood lead, r = -0.572, P less than 0.01; coproporphyrin, r = -0.608, P less than 0.01; delta-aminolevulinic acid, r = -0.559, P less than 0.01; urine lead, r = -0.453, P less than 0.05.

Adult↗
PubMed1978

Hemolytic pattern of erythrocytes in the newborn measured by the coil planet centrifuge system and its relationship to neonatal jaundice.

Dynamic osmotic fragility of erythrocytes in cord blood and its changes during the neonatal period were studied by means of a coil planet centrifuge system. The starting-point for hemolysis in the newborn become similar to that of adult blood after approximately a week, while the shift of the end-point to the adult range required one month or more. The percentage of fragile cord blood cells with a hemolysis starting-point above 110 m osmol and the maximum bilirubin level during neonatal period were examined. A high percentage of fragile cells was associated with high bilirubin levels, and when fragile cells comprised more than 7.0% of the total cord blood erythrocytes, the bilirubin level tended to rise above 15 mg/dl.

Bilirubin↗
PubMed1979

A proposal concerning the origin of life on the planet earth.

The widely accepted Oparin thesis for the origin and early evolution of life seems sufficiently far from the true state of affairs as to be considered incorrect. It is proposed that life on earth actually arose in the planet's atmosphere, however an atmosphere very different from the present one. Because of an extremely warm surface, the early earth may have possessed no liquid surface water, its water being partitioned between a motten crust and a fairly dense atmosphere. Early preliving systems are taken to arise in the droplet phase in such an atmosphere. The early earth, which resembled Venus then and to some extent now, underwent a transition to its present condition largely as a result of the evolution of methanogenic metabolism.

Animals↗
PubMed1981

Erythrocyte osmotic fragility in various liver diseases--application of coil planet centrifuge system.

A change in erythrocyte osmotic fragility was observed on various liver diseases by means of the coil planet centrifuge (CPC) system, and the relationship between changes in it and in serum lipids was studied. According to the CPC classification of hemolytic patterns of L, M, T and R, the frequency of appearance of T and R increased in liver cirrhosis and primary hepatoma. Hemolytic start and end points both changed considerably in primary hepatoma, acute hepatitis and liver cirrhosis. Change of hemolytic end point which shifted to the hypotonic side is more prominent than that of hemolytic start point. The hemolytic end point showed an inverse correlation to serum alkaline phosphatase and LAP, and correlation to pseudocholinesterase and albumin. Among the relations of red cell fragility and lipids of the lipoprotein fractions, free cholesterol and the ratio of free cholesterol to phospholipid in high density lipoprotein were both in remarkable inverse correlation to the hemolytic end point. Free cholesterol in high density lipoprotein was concluded one of the most important determinants of erythrocyte osmotic fragility.

Acute Disease↗
PubMed1992

Counter-current chromatography of lipoproteins with a polymer phase system using the cross-axis synchronous coil planet centrifuge.

Lipoproteins were separated by counter-current chromatography using the type-XLL coil planet centrifuge. The separation was performed with a polymer phase system composed of 16% (w/w) polyethylene glycol 1000 and 12.5% (w/w) dibasic potassium phosphate by eluting the lower phase at a flow-rate of 0.5 ml/min. About 5 ml of the sample solution containing approximately 150 mg of a lipoprotein mixture were loaded. High- and low-density lipoproteins were resolved within 12 h. Each component was detected by gel electrophoresis with oil red staining.

Centrifugation↗
PubMed1993

Studies on a new cross-axis coil planet centrifuge for performing counter-current chromatography. I. Design of the apparatus, retention of the stationary phase, and efficiency in the separation of proteins with polymer phase systems.

An improved model of the cross-axis synchronous flow-through coil planet centrifuge has been designed in light of previous studies. The apparatus has a versatile feature in that both analytical and preparative columns can be accommodated in both off-center and central positions. Each has merit in separations. Retention of stationary phase was examined with various two-phase solvent systems used for the separation of biopolymers. Both analytical and preparative columns showed satisfactory retention of the stationary phase under optimum conditions. The apparatus was evaluated in separation of a set of protein samples using a polyethylene glycol-potassium phosphate biphasic system. In both types of columns all proteins were resolved with partition efficiencies of 260 to 670 theoretical plates. Further studies indicated that the relatively low partition efficiency of proteins is mainly attributed to their high molecular mass or molecular heterogeneity within each species rather than due to the high viscosity of the polymer phase system.

Centrifugation↗