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At least 19 recordsLinked to original sources
PubMed1976

Controlled flocculation of coarse suspensions by colloidally dispersed solids I: Interaction of bismuth subnitrate with bentonite.

Deflocculated suspensions of coarse powders tend to cake as the individual particles settle out and form compact, cohesive sediments. Limited flocculation results in looser sediments because the settled-out flocs incorporate large amounts of the liquid suspending medium. Controlled flocculation of bismuth subnitrate suspensions was achieved by the addition of small amounts of bentonite. The interaction of the coarse, positively charge bismuth subnitrate particles in aqueous suspension with negatively charged, colloidally dispersed bentonite was investigated by measuring electrophoretic mobility, sedimentation volume, and viscosity. Gradual addition of bentonite dispersion to bismuth subnitrate suspensions first reduced the zeta-potential of the bismuth subnitrate particles from +28 mv to zero, then inverted it, and finally caused it to level off at -20 mv for bismuth subnitrate-bentonite weight ratios below 200. Owing to the much greater specific surface area of bentonite, the surface of the bismuth subnitrate lath-shaped crystals was completely covered by 0.5% of its weight in clay platelets. Adhesion was promoted by electrovalences between surface bismuthyl ions and cation-exchange sites of the clay and by secondary valences. The charge neutralization of bismuth subnitrate by bentonite was a heterocoagulation process: the addition of small amounts of the clay flocculated the bismuth subnitrate suspensions and eliminated caking. While the zeta-potential of the bismuth subnitrate particles leveled off when their surface was saturated with bentonite platelets, sedimentation volume and viscosity continued to increase when the clay concentration was increased further while maintaining the bismuth subnitrate concentration constant. The excess, nonadsorbed bentonite formed the characteristic house-of-cards structure, incorporating the bentonite-coated bismuth subnitrate particles as cornerstones.

Bentonite↗
PubMed1992

Effects of bentonite on wool growth and nitrogen metabolism in fauna-free and faunated sheep.

Two experiments were carried out with sheep that originated from a fauna-free flock and were fed a soybean meal-corn silage diet with or without a bentonite supplement. One-half of the sheep fed each diet in each experiment were faunated with a mixed population of ruminal protozoa, whereas the other half of the sheep remained fauna-free until the end of both experiments. Wool growth and daily gain were measured in Exp. 1. (eight rams per treatment), which lasted 110 d, and the metabolic effects in the rumen and intestinal tract of protozoa and dietary bentonite supplement were tested with cannulated wethers (four wethers per treatment) in Exp. 2. The results of Exp. 1 showed decreased wool growth (P less than .05) due to the presence of protozoa in the rumen. Dietary supplementation with bentonite partly offset the decreased wool growth in sheep with protozoa, but there were no effects of dietary bentonite and no protozoa x bentonite interaction (P greater than .05). Daily gain was decreased by the dietary bentonite (P less than .05) supplement but was not affected (P greater than .05) by the ruminal presence of protozoa. In Exp. 2, protozoa increased (P less than .01) the ruminal concentrations of ammonia and decreased (P less than .05) the acetic:propionic acid molar ratio. Fractionation of N in the duodenal digesta flowing from the stomach to the small intestine showed that protozoa decreased (P less than .05) the flow of nonammonia N and bacterial N, and there was a protozoa x bentonite interaction for these effects (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Effects of bentonite and monensin on selected elements in the stomach and liver of fauna-free and faunated sheep.

Forty-eight rams, originating from a fauna-free flock, were divided into three groups of 16 and fed a corn silage-based diet that was unsupplemented (control) or included bentonite or monensin supplements. Eight rams in each group were inoculated with a mixed population of ruminal protozoa; the other rams remained free of protozoa throughout the 110-d experiment. The rams had free access to drinking water and assigned diet. All rams were killed at the end of the experiment, and ruminal and abomasal contents and livers were removed and sampled. Protozoal numbers in ruminal fluid of faunated rams were lower for groups fed bentonite or monensin supplements than for the control group. Bentonite decreased and monensin increased ruminal pH. The ruminal solubilities of Cu, Zn, and Mg were decreased by the presence of ruminal protozoa, but those of Fe, Mn, and Ca were not affected. Bentonite supplement decreased, and monensin supplement increased, the ruminal solubilities of Cu, Zn, and Mg. Protozoa increased the abomasal solubilities of Fe, but the other elements were not affected. Liver concentrations of Cu were decreased by bentonite and increased by monensin, but protozoa decreased the liver concentrations of both Cu and Mg. Liver concentration of Zn was affected by a monensin x protozoa interaction and that of Mg by a bentonite x protozoa interaction. It was concluded that chronic Cu poisoning could be accelerated by dietary supplements of monensin in sheep without ruminal microfauna, and the dietary Cu bioavailability could be decreased by dietary supplements of bentonite in sheep with a normal population of protozoa in the rumen.

Abomasum↗
PubMed1978

Studies on the effect of quartz, bentonite and coal dust mixtures on macrophages in vitro.

The effect of quartz, bentonite and coal dusts as well as the effect of the artificial mixture of these dusts on TTC reduction and extra-and intra-cellular lactate dehydrogenase activity in peritoneal rat macrophages was determined in vitro. The cell-membrane-damaging effect of quartz caused a significant extracellular release of lactate dehydrogenase. Bentonite caused no extracellular enzyme release, which leads us to believe that the biological effect of this dust is shown by decrease in intra-cellular lactate dehydrogenase activity. TTC reduction was inhibited equally by quartz and qentonite. In mixtures of quartz (60%)-bentonite (40%) dust the specific effect of quartz was inhibited by bentonite in vitro and also in vivo. We obtained the same results with coal-quartz-bentonite dust mixtures in vitro. Our experiments show that comparison of the biological effects of artificial dust mixtures and airborne dust samples is justified, and prove that performing various examinations simultaneously give fuller particulars on the probable biological effect of mineral dusts.

Animals↗
PubMed1990

Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite.

The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaptation of the digestors, very rapid degradation of oil was observed and more than 80% of the oil was degraded within a few hours after daily feeding. In batch experiments, glyceride trioleate was found to be inhibitory to thermophilic anaerobic digestion when the concentrations were higher than 2.0 g/l. However, addition of bentonite (a clay mineral) at concentrations of 0.15% and 0.45% was found to partly overcome this inhibition. Addition of calcium chloride in concentration of 3 mM (0.033% w/v) showed a similar positive effect on the utilization of oil, but the effect was lower than with bentonite.

Anaerobiosis↗
PubMed1975

Preparation and properties of a cephalosporin acetylesterase adsorbed onto bentonite.

A cephalosporin acetylesterase produced by Bacillus subtilis was immobilized by adsorption onto bentonite. The immobilized enzyme (E(I)) and the soluble enzyme (E(S)) exhibited Michaelis-Menton kinetics with 7-aminocephalosporanic acid (7-ACA): K(m) = 2.8 x 10(-3) M and K(m) = 3.2 x 10(-3) M, respectively. Similar kinetics were observed with 7-(thiophene-2-acetamido)cephalosporanic acid (cephalothin), but the K(m) value measured with E(I) (3.7 x 10(-3) M) was less than one-half that measured with this substrate and E(S). The reduction in K(m) value was correlated with the ability of bentonite to adsorb cephalothin. The reaction products, acetate and deacetyl-7-ACA, were weak competitive inhibitors of E(S) and E(I). The K(i) values for E(I) were 5.0 x 10(-2) M for acetate and 3.6 x 10(-2) M for deacetyl-7-ACA. Similar values were measured with E(S) and these substrates. E(I) retained about 80% of its initial activity after 3 weeks of storage in solution at 25 C. However, the enzyme dissociated from the bentonite particles during the deacetylation reaction. This dissociation was minimized by cross-linking E(I) with glutaraldehyde or bis-dimethyladipimidate, or by adding Al(OH)(3) to the suspension. With the latter addition, E(I) was stabilized so that it could be reused nine times before one-half of the initial activity was lost.

Acetylesterase↗
PubMedDate not supplied

[The mechanism of plaque production by enteroviruses under bentonite overlay. Relationship between plaque production and the dynamics of intracellular virus reproduction and membrane potential of the host cell].

The association of plaque production under bentonite overlay with the cycle of intracellular reproduction of enteroviruses and the dynamics of the membrane potential of infected cells was studied. It was shown that by the time of termination of the intracellular enterovirus reproduction cycle (4 1/2-5 hours postinfection) bentonite particles were torn away from the cell surface. At the same time the membrane potential of the host cell began to decline progressively. The data obtained explain the character of morphology of virus plaques under bentonite overlay.

Bentonite↗
PubMed1976

[Metabolic activity of Candida lipolytica adsorbed to bentonite with hydrophobic chains].

The respiration of Candida lipolytica on n-tetradecane is decreased in the presence of bentonite. This inhibition is less pronounced by the introduction of hydrophobic chains on the bentonite. Oxygen demand of resting cells varies with the length of hydrophobic chains. In fermentor, addition of adsorbant does not stimulate growth, but assimilation of n-tetradecane is enhanced with certain concentrations of the adsorbant. On glucose, addition of hydrophobic chains on the adsorbant does not change the effects of bentonite on exogenous respiration and substrate assimilation.

Adsorption↗
PubMed1975

Studies of immunoglobulins, bentonite flocculation and IgE, IgG and IgM antibodies in serum from patients with trichinosis.

Serial serum samples were obtained from two patients from a family of four who ingested raw pork at a known time and in whom trichinosis developed. Single and occasionally two serum samples were obtained from other patients with proved trichinosis. Studies of these serum samples showed that elevations of serum immunoglobulin E (IgE) levels do occur but not in all serum samples and that even when these levels are elevated, they are not high enough to be of diagnostic value. This is also true for serum immunoglobulin M (IgM). Using a solid phase radioimmunoadsorbent test, IgE, IgG and IgM antibodies were detected in the serums. The IgE antibody activity appeared early but was not present in all samples. The IgM antibody activity appeared later than the IgE and IgG antibody activity, and there was a statistically significant correlation between IgM antibodies as determined by radioimmunoassay and the bentonite flocculation titers suggesting that the bentonite flocculation is due to IgM antibody. IgM antibodies detected by radioimmunoassay were positive in all serum samples from patients with trichinosis except for a sample obtained 3 days after the onset of symptoms. The early increase in IgG antibodies and the occurrence of these antibodies in all serum samples obtained more than 3 days after onset of symptoms suggest a potential diagnostic use if serial samples are available early in the course of the disease.

Bentonite↗
PubMed1977

[Adjustment of the ammonia level in the rumen by sorption on bentonite and dried beet pulp].

The effect was studied of bentonite and spent sugar beet pulp on the ammonia level in the rumen juice sheep fed hay, ground barley and a urea supplementation. In comparison with a control trial, the nitrogen supply to the rumen juice proved more continuous, this fact improving the conditions for the microbial protein synthesis at the time fo the strongest fermentation. The interaction of bentonite, beet pectin and ammonium ions is attributed to the ion exchange.

Adsorption↗
PubMed1975

Mechanism of the inhibitory effect of PAS granules on the absorption of rifampicin: adsorption of rifampicin by an excipient, bentonite.

The bioavailability (plasma concentrations, AUC and urinary excretion) of an oral solution of rifampicin was investigated in six healthy volunteers. Simultaneous administration of PAS granules produced a significant decrease in the absorption of RMP, whereas Na-PAS tablets had no effect. This indicated that the dosage form of the granules and not PAS itself was responsible for the interaction, and that the dissolution of RMP was not involved. The interaction could be reproduced by giving dummy granules that contained the same excipients but no PAS. The disintegration and dissolution of PAS granules in vitro correlated well with the disappearance of RMP from the solution. The major excipient of the granules, bentonite (a mineral closely related to kaolin), was found to adsorb rifampicin rapidly and strongly.

Adsorption↗
PubMed1975

Improved fibrin plate method for fibrinolytic activity measurements: use of bentonite precipitation and agar solidification.

A modification of the fibrin plate method to assure sterility and fibrin stability is described. Bovine fibrinogen is precipitated with bentonite to remove the plasminogen and agar is added to assure stability. Storage of the plates up to 7-10 days has resulted in no bacterial growth. This rapid, sensitive method is useful in the isolation of plasminogen or its activators by chromatographic separation.

Agar↗
PubMed1975

Effect of carrageenan on the development of hypersensitivity (Schistosoma mansoni egg) and foreign body (divinyl-benzene copolymer beads and bentonite) granulomas.

The effect of carrageenan on the development of hypersensitivity and foreign body granulomas was examined. Repeated intraperitoneal injections of the polysaccharide caused a strong suppression of the primary, hypersensitivity granulomas forming around the eggs of Schistosoma mansoni worms in the lungs of mice, but had no effect on the secondary, enhanced egg granulomas in the previously sensitized animals. Carrageenan treatment virtually abolished the granulomatous reactions forming around plastic beads or bentonite particles. It is concluded that carrageenan exerted its suppressive effect not through macrophage toxicity but rather by affecting plasma factors which regulate vascular permeability and cellular traffic during the process of inflammation.

Animals↗
PubMed1975

Anti-DNA Investigated the DNA bentonite flocculation technique.

The DNA bentonite flocculation test was used to investigate the presence of antibody to DNA. In most sera a prozone-like phenomenon was found, caused by a non-specific inhibition of serum. Anti-DNA was found with extreme frequency in patients with SLE, chronic liver disease, acute hepatitis, infectious mononucleosis, and blood donors over the age of 60, but was found rarely or not at all in patients with some other disease or blood donors under 60 years of age.

Adolescent↗
PubMed1978

[Use of an immunofluorescence method and a flocculation test with DNA-sensitized bentonite particles in the serodiagnosis of disseminated lupus erythematosus (SLE)].

The determination of antibodies against native DNA is of great importance in the solution of the diagnostic and therapeutic problems of dissiminated lupus erythematodes. The practical results are in a direct dependence on the laboratory methods for their determination. The diagnostic significance of two methods was studied with the present investigation: indirect immunofluorescent test and flocculation test with DNA-sensibilized bentonite particles. Under the conditions of the investigation, with the aid of the first method, antibodies against native DNA were found in 86.1 per cent of the sera of lupus nephropathy patients as well as in 13.3 per cent of the sera of patients with renal diseases not associated with LED. High serum titres including up to 1/128, were observed only in LED cases. The continuous persistence of antibodies against LED is also characteristic for the latter. The flocculation test was positive in 60.7 per cent of the sera investigated only with LED cases. The conclusion is that both methods could more wisely be used in LED immunodiagnostic because they combine high sensitivity with specificity of reaction, are easy to perform and no expensive material and apparatuses are required.

Adolescent↗