Analysis of the separation of gadolinium isotopes by the ICR method

The problem of separating gadolinium isotopes is discussed. The parameters of isotope separation in a plasma by the ICR method are estimated for a device with given operating parameters. The mean transverse energy 〈E_⊥〉 of the heated ions of the ¹⁵⁷Gd isotope and the heating efficiency η are calculated as functions of the frequency of the RF electric field in the plasma. The dependence of the heating efficiency η on the longitudinal temperature of the plasma flow is investigated. The issue of how the concentration of the target isotope ions at the collector plate depends on the longitudinal coordinate measured from the front edge of the plate is analyzed for different values of the frequency detuning parameter. The extraction coefficient Г for the target isotope is calculated as a function of the distance b between the collector plates for different frequency detunings.     

Calculation of the ion distribution function over transverse velocities under ICR heating conditions and separation parameters of a collector of heated ions

The ion distribution function over transverse velocities and the ion heating efficiency (which is defined as the fraction η of ions heated above a certain energy W_min) are calculated in the context of a plasma method for isotope separation on the basis of ion cyclotron resonance heating. The ion distribution function over longitudinal velocities is assumed to be linear in the range of low velocities. It is shown that, when the ions are heated to high energies, the averaged ion distribution function over transverse velocities becomes highly nonequilibrium and has two peaks. Results are presented from calculations of the ion heating efficiency η for W_min=40 eV and for different values of the parameter p that characterizes the ratio of the wavelength λ of the antenna electric field to the length L of the heating region. The relative roles of the time-of-flight and the Doppler broadening are analyzed, and the separation parameters of a collector of heated ions are estimated.     

TSE clearance during plasma products separation process by Gradiflow(TM).

BACKGROUND AND OBJECTIVES: Recent experimental evidence from rodent models suggests a potential risk for transmissible spongiform encephalopathy (TSE) transmission by blood. The emergence of a new variant Creutzfeldt-Jakob disease (vCJD) has raised increased concerns about the safety of blood components and plasma products derived from vCJD-infected donors. Recent risk-minimisation strategies have included a ban on the use of UK-sourced plasma for the preparation of licensed blood products and leukodepletion of blood donations for fear of possible transmission of the human TSE via blood or blood components. The aim of this study was to investigate the capability and efficacy of a preparative electrophoresis system (Gradiflow) in the removal of TSE contaminants during the separation of plasma products. MATERIALS AND METHODS: Using hamster adapted scrapie 263 K as a model for TSE agent, albumin and IgG separation from human plasma by Gradiflow were performed separately by spiking a 263 K scrapie microsomal fraction to the feed material at each process step. Samples from pre- and post-Gradiflow separation process were titrated to the end-point for the detection of the disease-associated, proteinase K resistant form of the pathogenic prion protein (PrP(Sc)) by Western blot. RESULTS: Under all conditions tested, a greater than 3 log(10) reduction was achieved with no PrP(Sc) detected in any of the pooled products for either of the IgG or albumin separations. These data show that Gradiflow processing has clear advantages for concurrent purification of plasma products and in-process TSE removal. CONCLUSIONS: Our findings suggest that Gradiflow process is a viable alternative to remove causative TSE agents during plasma products separation, potentially eliminating the risk of TSE agents transmission.     

Controlling plasma composition during carbon film deposition in microwave discharges by means of optical-emission spectroscopy

Optical emission spectra from the microwave discharge plasma that is used to activate gas-phase deposition of carbon films are systematically investigated under various deposition conditions. The line emission intensities from CH and C₂ radicals, which are responsible for the growth of the diamond and graphite phases, respectively, are studied as functions of the main macroparameters of the process. To find the relation between the features of the emission spectra and the composition of the films obtained, the films were examined using Raman spectroscopy and electron microscopy. It is shown that monitoring the relative intensities of the spectral lines can be used to obtain the desired type of film, in which case the state of the substrate surface and the presence of a catalyst on it also play an important role. Experiments on the deposition of carbon films in the pulsed regime of plasma excitation show the possibility of changing the phase composition of the film by varying both the pulse repetition rate and the off-duty factor. At the same average microwave power, the rate of film deposition in the pulsed regime of plasma excitation is lower than that in a continuous discharge; however, the growth rate of the graphite phase decreases insignificantly.     

Theory of the ICR heating of a plasma column: Methodological note

A set of wave equations is derived that describes electromagnetic waves at frequencies on the order of the ion gyrofrequency in a plasma column with an arbitrary electron temperature. This set takes into account, in particular, the resonant interaction of electrons with waves in the transit-time magnetic pumping regime. The effect of the amplification of the electromagnetic fields of current-carrying antennas by the plasma is analyzed. The evolution of the fields with an increase of plasma density from a zero value (vacuum) is considered. The main parameters are determined for minority ion cyclotron resonance heating in the planned EPSILON system.     

Alterations in lipid composition of plasma lipoproteins during deposition of egg yolk

The profiles of total lipids and of the molecular species of individual lipid classes were compared among corresponding lipoproteins of plasma and yolk of the laying hen. A close qualitative correspondence was found in the makeup of the molecular species of glycerophospholipids and triglycerides of the very low density lipoproteins and the high density lipoproteins of plasma and yolk. There was a lower proportion of the trienoic triglycerides and of the dienoic glycerophospholipids in the egg yolk than in the plasma lipoproteins, and the greatest differences (20-30%) were noted between the high density lipoproteins. It was also observed that the plasma high density lipoproteins lost their cholesteryl esters upon entering the yolk. On the basis of these and comparable analyses of the plasma lipoproteins of the nonlaying hen, it is concluded that the laying hen synthesizes specific lipoproteins for deposition in the yolk, and these are carried in plasma and selectively transferred to the developing ovum without significant equilibration with the other plasma lipoproteins.     

Fractionation of sulfur isotopes during thiosulfate reduction by Desulfovibrio desulfuricans

Sulfur isotope fractionation during reduction of thiosulfate was investigated with growing batch cultures of Desulfovibrio desulfuricans CSN (DSM 9104) at 30 °C. The sulfide produced was depleted in ³⁴S by 10‰ as compared to total thiosulfate sulfur. The depletion was equal to that during sulfate reduction under similar conditions. The two sulfur atoms of the thiosulfate molecule were affected differently by fractionation. Sulfide produced from sulfonate sulfur was depleted by 15.4‰, sulfide produced from sulfane sulfur by 5.0‰. Received: 29 October 1997 / Accepted: 18 December 1997     

Protein hydrogen exchange studied by the fragment separation method

The potential of hydrogen-exchange studies for providing detailed information on protein structure and structural dynamics has not yet been realized, largely because of the continuing inability to correlate measured exchange behavior with the parts of a protein that generate that behavior. J. Rosa and F. M. Richards (1979, J. Mol. Biol. 133, 399-416) pioneered a promising approach to this problem in which tritium label at exchangeable proton sites can be located by fragmenting the protein, separating the fragments, and measuring the label carried by each fragment. However, severe losses of tritium label during the fragment separation steps have so far rendered the results ambiguous. This paper describes methods that minimize losses of tritium label during the fragment separation steps and correct for losses that do occur so that the label can be unambiguously located and even quantified. Steps that promote adequate fragment isolation are also described.     

Assessment of renal function by the stable oxygen and hydrogen isotopes in human blood plasma

Water (H(2)O) is the most abundant and important molecule of life. Natural water contains small amount of heavy isotopes. Previously, few animal model studies have shown that the isotopic composition of body water could play important roles in physiology and pathophysiology. Here we study the stable isotopic ratios of hydrogen (δ(2)H) and oxygen (δ(18)O) in human blood plasma. The stable isotopic ratio is defined and determined by δ(sample) = [(R(sample)/R(STD))-1] * 1000, where R is the molar ratio of rare to abundant, for example, (18)O/(16)O. We observe that the δ(2)H and the δ(18)O in human blood plasma are associated with the human renal functions. The water isotope ratios of the δ(2)H and δ(18)O in human blood plasma of the control subjects are comparable to those of the diabetes subjects (with healthy kidney), but are statistically higher than those of the end stage renal disease subjects (p<0.001 for both ANOVA and Student's t-test). In addition, our data indicate the existence of the biological homeostasis of water isotopes in all subjects, except the end stage renal disease subjects under the haemodialysis treatment. Furthermore, the unexpected water contents (δ(2)H and δ(18)O) in blood plasma of body water may shed light on a novel assessment of renal functions.     

An effective method for plasma lipoprotein separation: studies of various animal species

1. Plasma lipoprotein separation by density gradient ultracentrifugation largely depends on visual examination based on the natural yellow pigments of lipoproteins. 2. In non-human species and in humans with dyslipoproteinemia, some lipoproteins are not well visualized due to the lack of pigments. 3. Using a fluorescent probe in minute quantity (1,6 diphenyl-1,3,5-hexatriene) we were able to demonstrate an effective plasma lipoprotein separation using a discontinuous density gradient ultracentrifugation technique. 4. Plasma lipoproteins of human, chicken, rat and carp were compared showing the unique character of carp HDL.     

Characterization of equine plasma lipoproteins after separation by density gradient

1. Plasma lipoproteins from six thoroughbred horses were separated by density gradient ultracentrifugation. For each sample, lipoprotein bands were visualized by means of a prestained plasma control and characterized by electrophoretic, chemical and morphological analysis. 2. Very low density lipoproteins (VLDL) were isolated at d less than 1.018 g/ml. 3. Two clearly resolved bands were detected in the low density lipoprotein fraction (LDL). The density limits were evaluated as follows: LDL1(1.028 less than d less than 1.045 g/ml) and LDL2(1.045 less than d less than 1.070 g/ml). Marked differences were observed in the chemical composition and particle size of LDL1 and LDL2 fractions. 4. High density lipoprotein fraction (HDL) was usually isolated as a single band, distributed over the range 1.075 less than d less than 1.180 g/ml. However, chemical composition and particle size revealed heterogeneity in HDL subfractions. 5. The density limit of LDL and HDL bands varied in each animal, indicating differences in equine lipoprotein distribution.     

The selection of a surfactant for freshwater microalgae harvesting and separation by the foam separation method

Bioprocess and Biosystems Engineering - Collecting microalgae from water with less energy and cost is significant to gain economic profit from microalgae harvesting and processing. Foam separation...     

Isotopic differences in the lithium transport rate in human erythrocytes during simultaneous incubations with the stable isotopes 6Li and 7Li.

The membrane transport of the two stable lithium isotopes, 6Li and 7Li, by erythrocytes has been studied using a dual channel atomic absorption spectroscopic technique. 6Li appears to be taken up preferentially to 7Li, in the ratio of 10 to 40%, depending on the concentration of total lithium and on the lithium isotopic ratio in the external medium.     

An improved method for the separation of proteins by zonal electrophoresis on density gradients

An apparatus for zonal electrophoresis of proteins is described. By starting with very thin sample layers, a mixture of three proteins could be completely resolved in its components. The apparatus can separate gram amounts of material in one single experiment. The potentialities of this approach for the separation of other particles (e.g., cells) are discussed.