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At least 649 records · Page 36Linked to original sources
PubMed2002

Oxidative pyrolysis of organic ion exchange resins in the presence of metal oxide catalysts.

Pretreatment of the organic ion exchange resins by oxidative pyrolysis is effective for volume reduction before vitrification. In this work, pyrolysis of two nuclear-grade resins, Purolite NRW100 (cationic) and NRW400 (anionic), was examined using a laboratory-scale theromgravimetric analyzer (TGA) in air. It was shown that the cationic resin was harder to degrade and was less volatile compared to anionic resin. Off-gas data revealed the presence of SO2, CO2, CO, and H2O during oxidative pyrolysis of cationic resin from 30 to 800 degrees C. Trimethylamine, CO2, CO, and ethyl formate were found in the case of anionic resin. In addition, oxidative pyrolysis of the mixed resins (50/50 wt.%) showed the existence of the gases nearly at the temperatures where the gases would evolve if the results of two different resins were superimposed. Several metal salts including CuSO4*5H2O, CuO, and FeSO4*7H2O, as well as the ions Cu2+ pre-loaded on the resins had a catalytic effect on the oxidative pyrolysis of cationic resins, in which the decomposition of functional groups and polymer matrices was enhanced. Such catalytic effect was highlighted by a large decrease in activation energy calculated according to a degradation mechanism involving four consecutive reactions.

Catalysis↗
PubMed1999

Sodium/hydrogen ion exchange inhibitor ameliorates ischaemia-reperfusion injuries in the rat hind limb.

PURPOSE: This study was designed to investigate the effect of a newly synthesised sodium/hydrogen ion exchange inhibitor, SM-20550, on ischaemia-reperfusion induced injury in a rat hind limb model. METHODS: In order to induce ischaemia of the hind limbs, the abdominal aorta just distal to the renal arteries and the bilateral femoral arteries were clamped. Nineteen rats were divided into three groups. In the sham group (n=5), the vessels were only dissected and a vehicle solution was administered. In the control group (n=7), the vessels were clamped for five hours, and a vehicle solution was administered 10 minutes prior to clamping and continued for five hours after reperfusion. In the SM group (n=7), clamping was maintained for five hours with a bolus injection of SM-20550 and continuous infusion of the solution for five hours after reperfusion. Water content of the left gastrocnemius muscle was calculated. The right gastrocnemius was fixed in 10% formalin. A transverse thin section was stained with antimyoglobin antibody. Stained cells of the right gastrocnemius were counted and the myoglobin staining index was calculated. RESULTS: Water content was significantly (p<0.002) lower in the SM group than in the control group. The myoglobin staining index was significantly (p<0.01) higher in the SM group than in the control group. There was no significant difference between the control and the SM groups in creatinine phosphokinase (CPK) and lactate dehydrogenase (LDH). CONCLUSIONS: Our results indicate that the sodium/hydrogen ion exchange inhibitor, SM-20550, ameliorates oedema formation and ischaemia-reperfusion induced injury of the skeletal muscle.

Amidines↗
PubMed2004

Simple one-step purification of nisin Z from unclarified culture broth of Lactococcus lactis subsp. lactis A164 using expanded bed ion exchange chromatography.

A simple one-step purification method, using expanded bed, ion-exchange chromatography, for the fractionation of nisin Z produced by Lactococcus lactis subsp. lactis A164 was developed. The highest dynamic binding capacity (0.92) of the adsorbent was obtained at a superficial velocity of 367 cm h(-1), resulting in approx. 2.7-fold bed expansion. The range of pH for the maximum adsorption was 3-4. The isocratic elution with 0.15 M NaCl led to approx. >90% recovery. Single-step purification of nisin Z from unclarified A164 culture broth resulted in 31-fold purification with a 90% yield.

Bacterial Proteins↗
PubMed1993

Quantification of physiological amino acids by gradient ion-exchange high-performance liquid chromatography.

A single-column gradient lithium ion-exchange chromatographic method with post-column derivatization and fluorimetric detection for the quantification of physiological amino acids is described. The method runs automatically, requires a minimum of sample preparation, separates all amino acids in plasma and cerebrospinal fluid, and most compounds in brain extract, in addition to some amino acids used therapeutically and in pharmacological studies. About 40 compounds can be quantitated within a run time of 3 h. The within-assay and between-assay coefficients of variations for principal amino acids in plasma samples are satisfactory. The system has performed conveniently and with high stability in the daily routine work and is cost-saving based on laboratory-prepared buffers.

Amino Acids↗
PubMed2006

Analysis of creatinine in mouse and rat serum by ion exchange high performance liquid chromatography for in vivo studies of renal function.

An ion exchange high performance liquid chromatography method was developed for determining creatinine levels in both mouse and rat serum samples. Separation of creatinine from other serum components was achieved in 10 min using a 100 x 4.1-mm, 10 microm strong cation exchange column following acetonitrile precipitation of serum proteins. Incorporation of a guard cartridge placed in-line prior to the analytical column was employed to prevent interference from compounds used in renal disease animal trials. Creatinine levels in normal and diseased animals were accurately determined in the 0.01-10 mg/dL range, and average recovery of the method was approximately 85% for both mouse and rat serum. Addition of 0.5-1.0% acetic acid to the acetonitrile used for protein precipitation significantly improved creatinine recovery to above 97% in mouse serum. The method was used for routine preclinical diagnosis of rat and mouse model renal function, and for the evaluation of renal disease treatment efficacy.

Animals↗
PubMed2002

A throughfall collection method using mixed bed ion exchange resin columns.

Measurement of ionic deposition in throughfall is a widely used method for measuring deposition inputs to the forest floor. Many studies have been published, providing a large database of throughfall deposition inputs to forests. However, throughfall collection and analysis is labor intensive and expensive because of the large number of replicate collectors needed and because sample collection and chemical analyses are required on a stochastic precipitation event-based schedule. Therefore we developed and tested a throughfall collector system using a mixed bed ion exchange resin column. We anticipate that this method will typically require only one to three samplings per year. With this method, bulk deposition and bulk throughfall are collected by a funnel or snow tube and ions are retained as the solution percolates through the resin column. Ions retained by the resin are then extracted in the same column with 2 N KCl and analyzed for nitrate and ammonium. Deposition values in throughfall from conventional throughfall solution collectors and colocated ion exchange samplers were not significantly different during consecutive 3- and 4-month exposure periods at a high (Camp Paivika; >35 kg N ha(-1) year(-1)) and a low deposition (Barton Flats; 5-9 kg N ha(-1) year(-1)) site in the San Bernardino Mountains in southern California. N deposition in throughfall under mature pine trees at Camp Paivika after 7 months of exposure was extremely high (87 and 92 kg ha-1 based on the two collector types) compared to Barton Flats (11 and 13 kg ha(-1)). A large proportion of the N deposited in throughfall at Camp Paivika occurred as fog drip, demonstrating the importance of fog deposition as an input source of N at this site. By comparison, bulk deposition rates in open areas were 5.1 and 5.4 kg ha(-1) at Camp Paivika based on the two collector types, and 1.9 and 3.0 kg ha(-1) at Barton Flats.

Ammonia↗
PubMed2003

Apertureless scanning near-field optical microscopy for ion exchange channel waveguide characterization.

We report the characterization of an integrated Ag+/Na+ ion exchange waveguide realized in a silicate glass substrate using apertureless scanning near-field optical microscopy. Our experimental set-up is based on the combination of a commercial atomic force microscope with an optical confocal detection system. Thanks to this system, the topography and evanescent optical field at the waveguide top surface are mapped simultaneously. Also, the process of apertureless scanning near-field optical microscopy image formation is analysed. In particular, fringe patterns appearing in the image reveal the intrinsic interferometric nature of the collected signal, due to interference between the field scattered by the tip end and background fields related to guide losses. We give a quantitative interpretation of these fringes. Evanescent intensity mapping on the sample surface allowed us to extract physical waveguide parameters. In particular, it shows an unambiguous multimode beat along the waveguide propagation axis. Furthermore, we show that analysis of this intensity profile reveals back-reflection effects from the waveguide exit facet. The resulting standing waves pattern allows us to evaluate the eigenmode propagation constants.

Equipment Design↗
PubMedDate not supplied

[Study of the ion transfer in membrane vesicles by ion exchange gel chromatography and ultrafiltration].

A method involving fast ion-exchange gel chromatography and filtration through ultrafilters is suggested for studying ion transport in membrane vesicles from bovine brain gray matter. The method permits separating quantitatively the membrane vesicles from the external radioactive label and studying kinetics of ion transfer. The label transfer is characterized by the presence of fast and slow phases and cannot be described by one exponential curve.

Animals↗
PubMed1976

Biological ion exchanger resins. X. The cytotonus hypothesis: biological contractility and the total regulation of cellular physiology through quantitative control of cell water.

Actin-like (A-L) fraction from normal E. coli was compared with the protein from a potassium-transport mutant strain, and the cell-swelling reaction of both strains was studied. Findings were: (a) The membrane fraction of the mutant by SDS electrophoresis is deficient in the A-L fragment relative to normal whereas the soluble supernatant contains an excess. (b) Important catalytic differences exist between the A-L fractions of the two strains. The parent strain accumulates potassium in low K+ and the A-L fraction polymerizes in low K+. But the A-L fraction from the mutant fails to polymerize in low K media in the K+ concentration region where the mutant fails at K+ uptake. (c) The parent cell swells during low K+ uptake whereas the mutant does not. It is constructed from this that the differences in the characterization of A-L fraction relative to normal are related to the loss of cell-swelling in the mutant and hence to the loss in alkali cation selectivity. Thus two physical mechanisms, one macroscopic and dependent on the Gregor relation for swelling equilibria in ion exchange resins, and one more microscopic based on the dielectric dependence of the coulomb force between ion pairs, could underly regulation of ion selectivity by cell swelling. A similar proposal is made for the regulation of electron transport and oxidative phosphorylation in mitochondria. These findings and interpretations justify a new hypothesis to the effect that cell hydration is regulated by contractile proteins. The hypothesis fits together important observations hitherto unexplained, to wit: (1) The "missing link" as to the role of intermediate metabolism in biological ion exchange. (2) The swelling of bacterial protoplasts and its relation to (Mg2 + Ca2+)ATPase activity. (3) The swelling-contraction cycles of mitochondria and their role in electron transport. (4) The role of ATPase's in transport. (5) The significance of actomyosin fibers in nerve endings. (6) The significance of altered actomyosin structures in the cancerous cell.

Actins↗
PubMed2004

Chromatofocusing of peptides and proteins using linear pH gradients formed on strong ion-exchange adsorbents.

Although it is commonly believed that a column packing used for chromatofocusing must have an "even" buffering capacity in order to produce a linear pH gradient, it is demonstrated here that linear pH gradients suitable for chromatofocusing can be produced on a column packing having a minimal buffering capacity. In particular, if either a strong-acid cation-exchange column packing or a strong-base anion-exchange column packing is presaturated with either a weak acid titrated with a strong base, or a weak base titrated with a strong acid, respectively, to the initial pH, then a linear or nearly linear pH gradient can be formed using a polyampholyte elution buffer by taking advantage of the presence of small quantities of weak-acid or weak-base functional groups that generally exist on these types of column packings. Experimental and theoretical studies are used to demonstrate that such systems have potential advantages over traditional chromatofocusing methods in terms of the speed of the separation, the resolution achieved, and the range of applications possible. Among other techniques described, a method for separating tryptic peptides using chromatofocusing and a strong-acid cation-exchange column packing is demonstrated to be a useful alternative to capillary isoelectric focusing and ion-exchange chromatography using a salt gradient for this purpose.

Adsorption↗
PubMed2006

The determination of nicotinic acid in plasma by mixed-mode liquid chromatography-tandem mass spectrometry following ion exchange solid phase extraction.

An assay for nicotinic acid in plasma samples has been developed using ion exchange solid phase extraction in 96-well format followed by mixed-mode ion exchange/reversed-phase liquid chromatography with positive ion tandem mass spectrometry detection. The assay avoids the need for time-consuming derivatisation procedures or involatile ion-pair chromatography reagents. The assay is linear over the wide range 0.05-20 microg/mL, based on a 100 microL sample (correlation coefficient>0.99). The assay is accurate and precise (bias and coefficient of variation<18%) over this calibration range.

Administration, Oral↗
PubMed2004

Purification of RanGDP, RanGTP, and RanGMPPNP by ion exchange chromatography.

Ran is a small GTPase that cycles between a guanosine diphosphate (GDP)-bound form (RanGDP) and a guanosine triphosphate (GTP)-bound form (RanGTP) and plays important roles in nuclear transport and mitosis. For studies of Ran function and its interactions with partner proteins, pure RanGDP and RanGTP complexes are critical. Ran complexed with the nonhydrolyzable GTP analog, GMPPNP (RanGMPPNP), is used instead of RanGTP when inhibition of hydrolysis is required. In this study, we demonstrate that the binding of Ran to a UNO Q ion exchange column is remarkably sensitive to small shifts in MgCl(2) concentration, and we use this property to purify recombinant RanGTP, RanGMPPNP, and RanGDP complexes. At 10 mM MgCl(2), Ran was found predominantly in the flow-through and, thus, was separated from the vast majority of bacterial proteins. After reducing the concentration of MgCl(2) to 5 mM, further purification of RanGTP, RanGMPPNP, and RanGDP was achieved by loading onto ion exchange columns and elution with an NaCl gradient. Purity of the resulting preparations was confirmed by releasing the bound nucleotide and checking it against a known nucleotide by high-performance liquid chromatography (HPLC). To further confirm the purity and function of the Ran preparations, appropriate protein-binding, enzymatic, and nuclear import assays were carried out. These methods should facilitate studies of cellular processes involving Ran by providing pure functional Ran-nucleotide complexes.

Chromatography, High Pressure Liquid↗