Fraction Of Cs Research Articles

A Study on the Hydration of Bombyx mori Silk Fibroin by Nuclear Magnetic Resonance Spectroscopy.

We have recorded several kinds of 13C NMR to characterize the structure of the noncrystalline domain in Bombyx mori silk fibroin and the influence of hydration on the structure of silk fibroin. First, the structural analysis of the soluble fraction (noncrystalline domain) after chymotrypsin hydrolysis of the silk fibroin has been performed by 13C solution NMR spectroscopy. In the noncrystalline fraction. Cs fraction, the C-terminal amino acid residues are identified as---Gly-Tyr from the pH titration of the spectra. Similarly, the N-terminal residues are identified as Gly-Ser---. Second, the 13C CP/MAS NMR spectra for the precipitated fraction (Cp fraction; crystalline domain) and Cs fraction have been observed as a function of moisture regain in order to know what parts, residue or groups, interact with the adsorbed water. In the Cp fraction, the significant spectral changes were not observed with increasing water content. However, in the Cs fraction, the significant changes were observed at the carbonyl carbon peak of the N-terminal Gly residue and the aromatic Cγ carbon peak of the C-terminal Tyr residue by hydration. Third, the 1H NMR spin-lattice relaxation times, T1 of water in Cp and Cs fractions were observed. The T1 values were analyzed as two components for the Cp fraction and three components for the Cs fraction. The water molecules with the restricted motion increase considerably in the Cs fraction and such a restricted motion is roughly divided into two cases. This seems to be corresponding to the strongly hydration at the terminal groups observed in the 13C CP/MAS NMR spectrum of the Cs fraction.

Mobilization and fractionation of137Cs in calcareous soils

Mobility of137Cs was investigated in columns of calcareous loam and clay soils leached under river water, NH4OAc, KCl, CaCl2, and EDTA. Fractionation of Cs into ten sequential fractions was accomplished in the leached soils as well as in soil samples received carrier-free137Cs and incubated for 60 d. At the end of 90 d of leaching with river water and CaCl2, the bulk of Cs applied (>97%) was found to remain in the upper 1 cm of soil columns. On the other hand, the reduction in Cs concentration was approximately 30% with NH4OAc, 18% with KCl, and 10 to 25% with EDTA. The major soil constituents appeared to be responsible for retaining Cs were clay, silt, and Fe oxides. The leaching consistently increased the magnitude of fractions bound to clay minerals and in most cases decreased the fractions of water soluble, exchangeable, carbonate, and organic matter.

The effect of the outer membrane fraction of Bacteroides gingivalis W50 on glycosaminoglycan metabolism by human gingival fibroblasts in culture

The synthesis of extracellular [ 35S]-SO 4- and [ 3H]-glucosamine-labelled glycosaminoglycan (GAG) was studied in confluent human gingival fibroblast cultures in vitro. The differential synthesis of the total chondroitin sulphate/dermatan sulphate ( CS DS ) and heparan-sulphate (HS) fraction was measured following chondroitinase-ABC digestion, nitrous-acid treatment and column chromatography on Sephadex G50. Control cultures synthesized a CS DS fraction that represented 78 per cent of the total [ 35S]-SO 4-GAG; the residual 22 per cent was heparan sulphate. Similar cultures were labelled with [ 3H]-glucosamine and the proportions of a high molecular-weight hyaluronic acid (HA) and proteoglycan fractions measured by gel-filtration HPLC after papain and hyaluronidase digestions. The HA fraction represented 66 per cent of the total isotope incorporated in control cultures. GAG chains released on treatment with papain (24 per cent of the total label incorporated) were of apparent molecular weight 17–20 kDa. All cultures exposed to Bacteroides gingivalis W50 outer membrane at concentrations between 2 and 50 μml −1displayed a decrease in the CS DS fraction and a reciprocal increase in the HS. However, the proportion of HA synthesized was slightly enhanced with a reciprocal decrease in the proteoglycan (papain-digestible) fraction. There was no alteration in the molecular weight of the papain-digestion products or the size distribution of the hyaluronic-acid fraction.

The interaction of trace levels of cesium with montmorillonitic and illitic clays

The interaction of Cs + with a montmorillonitic and an illitic clay suspended in solutions of synthetic groundwaters, sodium perchlorate, or sodium acetate was examined over the range of initial Cs + concentrations of 10 −8 to 10 −5 mol/l and at 25° and 80°C. The clays are being considered as possible components of barrier materials in a nuclear fuel waste disposal vault in Canada. Both clays sorb more Cs + at 25° than at 80°C, suggesting an exothermic reaction. Less Cs + is sorbed at pH=5 than at pH⋍8.5 . The lower the K + concentration in the suspending media, the more Cs + is sorbed by the clays. The illitic clay has a greater sorption capacity and affinity for Cs + than does the montmorillonitic clay, even though the montmorillonite has a significantly greater cation exchange capacity and specific surface area. It is likely that a large fraction of Cs + is selectively sorbed and fixed on specific sites in the edge-interlayer region of clays like illite. The montmorillonitic clay, which contains ∼10% illite, fixes some Cs + but less than the illitic clay. The results indicate that, for the disposal of nuclear fuel waste containing 135Cs, the illitic clay would be a more effective component of the barrier material than the montmorillonitic clay for slowing the migration of 135Cs.

Characterization of carbon disulfide binding in blood and to other biological substances

Free and bound forms of CS 2 are present in subjects exposed to CS 2. In rats exposed to 2 mg/liter (∼640 ppm) of CS 2 for 4 hr, concentrations of acid-labile CS 2 (AL CS 2, a form of bound CS 2 that can be recovered from biological samples by acid treatment) in plasma and red blood cells (RBCs) increased linearly with exposure time. The majority (90%) of the blood AL CS 2 was present in the RBCs. About 95% of the AL CS 2 in plasma and in RBCs of exposed rats was found in the precipitates after treatment with ammonium sulfate. Incubation of fractionated human RBC lysates with CS 2 showed that CS 2 binding in these fractions was proportional to the hemoglobin concentration. These observations show that in blood, CS 2 binds (in the form of AL CS 2) mainly to hemoglobin and to a small extent to other blood proteins. Binding of CS 2 to small molecules, including amino acids, accounted for only a small fraction of blood AL CS 2. In in vitro studies, CS 2 also bound to human albumin, γ-globulin, and horse heart myoglobin. It was also found that CS 2 binds to amino and sulfhydryl compounds at physiological pH. Plasma incubated with CS 2 was found to chelate copper. Chelation of copper-containing enzyme by the reaction products of CS 2 and biological amines has been observed and has been proposed as one of the mechanisms by which CS 2 induces neurotoxicity ( M. J. McKenna and V. Distefano, 1977b, J. Pharmacol. Exp. Ther. 202, 253–266). Radioisotope studies showed that a substantial portion of the radioactivity could not be released from 14CS 2-treated plasma and serum upon acid treatment at elevated temperature. These studies suggest the existence of non-acid-labile bound CS 2, besides AL CS 2, in plasma and serum treated with CS 2.

Characterization of cleavage stage chromosomal proteins from zygotes of the sea urchin, Tetrapygus niger

1. 1. Cleavage stage chromosomal proteins were isolated from very early embryos of the sea urchin Tetrapygus niger. 2. 2. Seven major proteins, specified CS A, CS B, CS C, CS D, CS E, CS F and CS G, were purified by electroelution from urea/acetic acid gels. 3. 3. These proteins exhibited an electrophoretic behaviour similar to histones except H 2A, but their amino acid analysis reveal that, with the exception of CS E, the CS proteins do not show the general compositional characteristics of histones. 4. 4. These results indicate that the CS fractions are unique chromosomal proteins, related to histones in their function but not in their primary structure.

Activated macrophages secrete a soluble factor that inhibits mitochondrial respiration of tumor cells.

Conditioned supernatants (CS) obtained from activated murine peritoneal macrophages inhibit tumor cell mitochondrial respiration. EMT-6 cells exposed to CS were markedly inhibited in their ability to oxidize succinate (11.8 ng-atoms 02/min/10(6) cells base line; 3.2 CS treated), malate (15.4 base line, 3.6 CS treated), and tetramethylphenylenediamine (27.6 base line, 10.6 CS treated). The CS was also found to inhibit DNA synthesis in EMT-6 cells (98.9% inhibition of [3H]thymidine incorporation), but did not cause cell lysis. Mitochondrial respiration inhibition activity was not detected in CS until 4 hr; it reached a maximum at 18 hr and declined rapidly by 24 hr. EMT-6 cells recovered from inhibition if the CS was removed from culture, but no recovery was observed if the target cells were in continuous exposure to CS for 72 hr. Fractionation of CS by using a molecular exclusion column of Sephacryl S-200 resulted in the recovery of two peaks that showed respiration inhibitory activity. These peaks, eluting at 55,000 and 80,000 daltons, mediated the inhibition of malate and succinate oxidation and were cytostatic for EMT-6 cells.

Zeolites for fixation of cesium and strontium from radwastes by thermal and hydrothermal treatments

Several zeolites, minerals commonly used in radioactive waste decontamination, were heated in air up to 1000 °C for 4 h or heated hydrothermally at 300 °C for 4 weeks under a confining pressure of 300 bar after loading with Cs or Sr to determine the extent and nature of Cs and Sr fixation. Cs-loaded zeolites leached with 0.1 v KC I solution indicated that clinoptilolite, chabazite, erionite, and mordenite fixed only 7% to 26% of their Cs after heat treatment up to 800 °C. However, analcite and phillipsite fixed 84% and 81% of their Cs by heat treatments to only 200 and 500 °C, respectively. The fixation in analcite may be attributed to its dehydration, while in phillipsite the fixation is attributed to its transformation to Cs-feldspar-type phase at 500 to 800 °C. At 1000 °C, all the zeolites seem to be very effective in Cs fixation by forming cesium aluminosilicate minerals. Partially Cs-loaded phillipsites also fixed substantial fractions of their Cs by heat treatment in air as a result of the formation of the feldspar phase. Hydrothermal treatment of Cs-loaded zeolites resulted in the formation of pollucite with phillipsite, erionite, and chabazite and thus fixed Cs. All the Sr-loaded zeolites when leached with KCl were found to fix Sr by thermal treatment at 350 °C and fixed substantial fractions by treatment at 600 °C. For example, at 600 °C clinoptilolite, mordenite and erionite fixed 91%, 93%, and 73%, respectively, of the original Sr present in the samples. Analcite and phillipsite were also very effective in Sr fixation just as they were in Cs fixation. Analcite and phillipsite fixed 86% and 91% of their Sr by heat treatment to 420 and 600 °C, respectively. The fixation of Sr by phillipsite was probably due to its transformation to celsian. Hydrothermal treatment of Sr-loaded phillipsite, clinoptilolite, and mordenite also resulted in substantial Sr fixation. These results show that analcite and phillipsite fix the greatest fractions of Cs and Sr at the lowest temperature of treatment. Between analcite and phillipsite, the latter has the greatest capacity and selectivity for Cs and Sr when used in decontaminating radioactive waste solutions and, therefore, phillipsite may be ideally suited for radioactive waste decontamination followed by thermal or hydrothermal treatment to fix the sorbed Cs and Sr.

Sorption of Cesium by Soils and Its Displacement by Salt Solutions

AbstractCesium was sorbed by montmorillonite, illite, and kaolinite in quantities corresponding to exchange saturation and was displaced readily on leaching with 1N KCl or CaCl2. Vermiculite and heated (600°C., 12 hours.) K‐montmorillonite bound Cs tightly against displacement by CaCl2 and AlCl3, but not by KCl or NH4Cl. Prolonged leaching with 1N KCl removed 97.5% of the Cs sorbed by heated K‐montmorillonite, while 1N CaCl2 eventually displaced 88%.Potassium and Rb sorbed on vermiculite were displaced more rapidly by Ca or Mg than by monovalent ions, but this was not the case with heated K‐montmorillonite.The exchange‐displacement behavior of Cs on vermiculite and heated K‐montmorillonite suggests that this ion is unique in that its sorption in interlayer spaces leads to interplanar distances which admit K and NH4 ions but greatly restrict the entry of Ca. Cesium, then, is not expected to follow the “fixation‐release” rules that have been developed for K and NH4.Heated montmorillonite samples leached with mixtures of CsCl and other salts sorbed more Cs when the complementary ion was Ca or Al than when it was K or NH4. Differences were especially pronounced at low equivalent fractions of Cs in the leaching solution, showing a larger preference by exchange sites for Cs over divalent than over monovalent ions. Apparent “specific sorption” of Cs against exchange with CaCl2 occurred at quite large Cs saturations.

The uniformity of concentration of lithophile elements in chondrites—with particular reference to Cs

The paper is in two parts. In the first, the dispersion of concentration of the lithophile elements Li, Na, K, Rb, Mg, Ca, Sr, Ba, Al, Sc, Eu, Si, Ti, Zr, Th and U is examined in chondrites. Where twenty or more analyses have been made, relative deviations have been calculated; these range from 5 to 29 per cent. Some of the variation is clearly due to analytical error and it is concluded that the relative deviations of most, perhaps all, lithophile elements is near the lower limit (5 per cent) of the above range. Such small dispersion of concentration for a wide variety of elements, including Li, K and Mg which are sensitive to fractionation, indicates that chondrites have come from a source with an exceptionally uniform composition. It is concluded further that variation of concentration of a lithophile element in the silicate phase, as distinct from the meteorite as a whole, may be even smaller and that the ratio of one lithophile element to the other lithophile elements may turn out to be extremely small indeed. Analytical data of a very high order of excellence (relative deviation of 1–2 per cent) for all elements are evidently required to estimate such small variations precisely. The second part of the paper is concerned specifically with caesium. This element has been estimated spectrochemically in K—Rb—Cs fractions obtained by ion exchange techniques from six chondrites and seven specimens of basic rock. In the chondrites, the Cs content (ave. 0.12 p.p.m.) and the K/Cs ratio (ave. 7000) remains constant to within the precision of the method of analysis. The magnitude of the average agrees with that (0.09 p.p.m.) of Webster, Morgan and Smales but the small variation of the Cs concentration and of the K/Cs ratio contrasts with their observations as they report large variations (× 30 or more). The K/Cs ratio in the seven basic rocks is fairly uniform (in contrast with granites) and similar in general magnitude to that in the chondrites.