Showing papers on "Chemical binding published in 1986"

Particle separation method

Abstract: A method is disclosed for separating a substance from a liquid medium. The method comprises combining the liquid medium containing the substance with magnetic particles under conditions for non-specific chemical binding of the magnetic particles. Thereafter, the medium is subjected to a magnetic field gradient to separate the particles from the medium. The preferred non-specific binding is achieved as the result of charge interactions between the particles usually by means of a polyionic reagent. The method of the invention has particular application to the separation of cells and microorganisms from aqueous suspensions and also to the determination of an analyte in a sample suspected of containing the analyte. The analyte is a member of a specific binding pair (sbp). The sample is combined in an assay medium with magnetic particles and a sbp member complementary to the analyte. Magnetic or non-magnetic particles capable of specific binding to the analyte or its complementary sbp member must be included in the assay medium. The combination is made under conditions for non-specifically aggregating the magnetic particles or coaggregating the magnetic and non-magnetic particles when non-magnetic particles are present. The assay medium is subjected to a magnetic field gradient to separate the aggregated particles from the medium. Then, the medium or the particles are examined for the presence or amount of the analyte or an sbp member, the binding of which is affected by the presence of the analyte.

Reflection of Heavy Ions

Abstract: The backscattering of heavy ions from surfaces is investigated by computer simulation (TRIM.SP). The particle and energy reflection coefficients are shown to scale with the ratio of target mass to ion mass as well as with the reduced energy e for e>0.02 and for normal incidence. At lower energies not only the scaling breaks down but also the effect of a chemical binding influences the reflection coefficient. The calculated data include also the dependence of the reflection coefficients on the angle of incidence as well as angular and energy distributions. Simulated results are in reasonable agreement with those from analytical theory and experiment.

Apocytochrome c binding to negatively charged lipid dispersions studied by spin-label electron spin resonance.

Abstract: The interaction of apocytochrome c with aqueous dispersions of phosphatidylserine from bovine spinal cord and with other negatively charged phospholipids has been studied as a function of pH and salt concentration by using spin-label electron spin resonance (ESR) spectroscopy and chemical binding assays. The ESR spectra of phospholipids spin-labeled at different positions on the sn-2 chain indicate a generalized decrease in mobility of the lipids, while the characteristic flexibility gradient toward the terminal methyl end of the chain is maintained, on binding of apocytochrome c to phosphatidylserine dispersions. This perturbation of the bulk lipid mobility or ordering is considerably greater than that observed on binding of cytochrome c. In addition, a second, more motionally restricted, lipid component is observed with lipids labeled close to the terminal methyl ends of the chains. This second component is not observed on binding of cytochrome c and can be taken as direct evidence for penetration of apocytochrome c into the lipid bilayer. It is less strongly motionally restricted than similar spectral components observed with integral membrane proteins and displays a steep flexibility gradient. The proportion of this second component increases with increasing protein-to-lipid ratio, but the stoichiometry per protein bound decreases from 4.5 lipids per 12 000-dalton protein at low protein contents to 2 lipids per protein at saturating amounts of protein. Apocytochrome c binding to phosphatidylserine dispersions decreases with increasing salt concentration from a saturation value corresponding to approximately 5 lipids per protein in the absence of salt to practically zero at 0.4 M NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoassay system and procedure based on precipitin-like interaction between immune complex and Clq or other non-immunospecific factor

Abstract: A test system and procedure for quantitatively assaying biological material for a target immunological substance by means of immunochemical binding of immune complexes, comprising the target substance and its immunospecific conjugate, to insolubilized non-immunospecific factor, such as Clq. A sample of biological material suspected of containing the target substance is introduced into the test system including pre-determined amounts of the target substance and its immunospecific conjugate forming immune complexes having a known degree of chemical binding to the non-immunospecific factor. The amount of target substance present in the test sample is determined according to the deviation from the known degree of immunochemical binding caused by the addition of the sample to the test system, by reference to a standard curve.

Energy loss of 4He ions in AI2O3 and SiO2

Abstract: From the 4He energy loss measurements in Al, Al2O3, Si and SiO2, we have extracted stopping cross sections for “solid” oxygen over the energy range 0.2 to 2 MeV and at 5.48 MeV. Assuming linear additivity of atomic stopping cross sections, values for oxygen are 5.3 to 15% higher in SiO2 than in Al2O3, indicating that discrepancies in the Bragg rule for these oxides are clearly not due to phase effects but to chemical binding effects.

Synthetic membrane active polyelectrolytes in design of artificial immunogens and vaccines

Abstract: Chemical binding or strong complexing of individual antigens (proteins, polysaccharides) or antigenic determinants with non-natural membrane active polyelectrolytes results in formation of effective immunogens with high protective properties. These artificial antigenic conjugates develop strong immunogenicity also in the absence of T-cells. The strength of the immune response is not controlled by Ir-genes. An antigenic moiety of a conjugate is responsible for its “focusing” on B-lymphocytes of the proper clone. Linear polyion moiety being adsorbed on the cell membrane surface aggregates membrane proteins and induces nonspecific transmembrane ionic permeability. K+-flux from the cell and Ca+2-flux into the cell disturb cell homeostasis and thus, pull trigger mechanism of K+, Na+-ATPase and Ca+2-ATPase activity. Then the cell synthesizing apparatus starts to operate. The covalent conjugates of Salmonella typhimurium and influenza A-virus individual antigens with synthetic polyelectrolytes seem to represent a new generation of vaccinating macromolecules.

Endotoxin inactivation in plasma from septic patients: An in vitro study

Abstract: Patients with suspected septicemia were screened for endotoxemia with a quantitative chromogenic assay. In some patients endotoxin concentrations were within the range of healthy controls. Eleven of these were patients on intensive care with severe, culture-verified, gram-negative infections in blood or other foci. One possible explanation for this paradoxical absence of endotoxin is increased plasma inactivation. In order to test this hypothesis, endotoxin was added to platelet-rich plasma from these patients to give a concentration of 100 ng/l, and serial quantitative determinations were made for 2 hours. Plasma from 11 healthy individuals served as controls. In the first sample, measured immediately after addition of endotoxin, a mean of 97.3 ng/l was recovered in plasma from healthy individuals and only 75.8 ng/l in the septic plasma (p<0.05). When kept on ice, these concentrations were maintained, while at +37‡C they decreased rapidly at rates that were equal in both septic and control plasmas. In a corresponding study in platelet-free plasma, it was found that the platelets could not account for this inactivation. The results demonstrate the possibility of immediate endotoxin inactivation in plasma from patients with sepsis, probably caused by chemical binding.

Characterization of Metal-Complex-Containing Organic Polymeric Films by Secondary Ion Mass Spectrometry

Abstract: The SIMS technique has been successfully applied as an analytical tool for the chemical and spatial analysis of metal-complex-doped polymeric films. The polymeric matrix was chlorosulfonated polystyrene (approx.1000 A thick) cast onto a smooth platinum substrate, and following subsequent incorporation of metal complexes containing Ru, Re, or Zn by chemical binding, the SIMS technique was found to be chemically selective and sensitive to the Ru, Re, and Zn sites in the polymeric films. Qualitative assays of the films using secondary ion mass spectra were carried out with relative ease, but determinations of the spatial distribution of metal sites throughout the films require highly controlled sample preparation. The results of a series of studies on polymeric films containing various levels of the Ru complex showed that signals for Ru/sup +/ are influenced by local variations in ion yield, i.e., ion yield transients near the polymeric surface and at the polymer/platinum interface. A normalization procedure based on comparisons of Ru/sup +/ to O/sup +/ secondary ion intensities reduces the influence of such artifacts in the analysis of the concentration depth profiles of the complexes within the polymeric films.

Process for reducing the content of noxious matter in dust-containing flue or process gases

Abstract: Process for reducing the content of noxious matter in dust-containing flue or process gases by means of an injection cooler as well as by the use of an adsorber in conjonction with a regenerator and of activated coke charges fed through these, whereby the gases with their dust-content prior to filtering are past through at least one injection cooler with the simultaneous addition of ammonia as an additive for the chemical binding of the large if not almost total content of the SO3 and halogen as well as for separating and precipitating the thus formed ammonia salts and heavy metals on the dust. The dust charged with the precipitated salts is withdrawn by filtering and prepared for recovery of the ammonia. After filtering of the solids contained therein the flue gases are fed through the activated coke charge(s) of the adsorber, so that essentially only SO2 is separated in the absorber, this being recovered from the activated coke by its treatment in the regenerator and being fed for further processing.

Lattice dynamics and chemical binding in semiconducting compounds II-IV-V 2

Abstract: A review is given of experimental studies of infrared absorption, reflection, and Raman scattering of light on single crystals of I!--IV--V2 compounds. A rigid ion model is discussed as applied to the calculation of phonon spectra of ternary compounds with the chalcopyritetype lattice. In the simplest version of the model, short-range forces in the nearestneighbor approximation are given with the help of three parameters; Coulomb forces in the model of unpolarized ions are determined by two parameters. The dependence of phonon spectra on the ratio of cation masses is analyzed: a similarity between phonon spectra of ternary compound with similar cation masses and analogous binary compounds, placed in the Brillouin zone of chalcopyrite, as well as significant qualitative differences between spectra of binary and ternary semiconductors for a significant difference in cation masses is indicated. The calculated frequency density function, taken with a double scale g(2~), describes qualitatively the full symmetry component of the Raman scattering spectrum of second order. From the analysis of calculated elastic constants is has been established that in a number of ternary compounds a tendency is observed for decrease of elastic constants as the average atomic number is increased. Anisotropy of propagation of elastic waves in ternary compounds is analyzed. From the comparison of theoretical and experimental temperature dependences of the specific heat it has been shown that the Debye model does not describe experiment as well as the model which takes into account the real structure of the phonon spectrum.

Crystallization and melting of polyethylene oxide in a system with a jointly cured densely crosslinked polymer

Abstract: The calorimetric method has been employed to study the patterns of crystallization and melting of polyethylene oxide in a system with a melamine formaldehyde polymer cured jointly with it The topology of the spatial densely crosslinked polymer network and chemical binding of the terminal groups of polyethylene oxide were found to have a strong influence on its behaviour on crystallization and melting

Changes in Important Biochemical Parameters Due to Extreme Haemodilution with Cross-linked Stromafree Haemoglobin Solution

Abstract: Transport of biological available oxygen in vertebrates is performed by two different principles: physical solution in plasma and chemical binding to the haemoglobin molecule. According to these principles the development of oxygen-carrying colloids proceeds along two different pathways. The fluorocarbons increase the amount of physically dissolved oxygen due to the extraordinary oxygen-solubility of these compounds [7]. Some research groups have favoured the development of stroma-free haemoglobin solutions (SFH). These compounds chemically bind oxygen similar to the natural intraerythrocytic haemoglobin [2, 6]. In particular, Bonhard and coworkers have been able to improve the oxygen-transporting property and the intravascular persistence of these SFH solutions [1, 3]. The former was achieved by pyridoxalation and the latter by intermolecular crosslinkage of haemoglobin molecules. This new type of SFH was called “nhpa”, where “n” means polymer, “h” means haemoglobin, “p” means pyridoxalation and “a” means albumin addition for correction of oncotic pressure. This 8.5% nhpa is a research product of Biotest-Pharma, Frankfurt. With this oxygen-carrying colloid we performed extreme isovolemic haemodilution in dogs and examined the changes in different biochemical parameters.