Composition, structure, and luminescence of montmorillonites saturated with different aggregates of methylene blue.

The distribution of various aggregates (dimers, trimers, and tetramers) of methylene blue (MB) formed in aqueous solution at various concentrations of dye has been calculated using the equilibrium aggregation constants betaq. Two montmorillonite samples with different cation exchange capacities, surface areas, and interlayer distances d001, Na-SWy, and Ca-Cheto, were saturated with methylene blue (MB) solutions with various ratios between monomers and higher aggregates of dye. The total amount of MB in the intercalated montmorillonite samples (MB-SWy and MB-Cheto) increases with increasing concentration of dye in water solutions, i.e., with increasing aggregates/monomers ratio of MB in water solution. In all intercalated montmorillonite samples with methylene blue except guest qth aggregate cations [MBqq+] low contents of Na+ (in MB-SWy) and Ca2+ (in MB-Cheto) cations were also determined. A very good positive correlation between the basal spacing d001 and the MB/montmorillonite molar ratio was revealed for saturated MB-montmorillonite samples. Structural analysis using a combination of diffraction data with molecular modeling revealed the differences in the interlayer arrangement of MB guests in MB-SWy and MB-Cheto intercalates. Also, fluorescence measurements showed the strong effect of the silicate layer charge on the spectroscopic behavior of MB guests intercalated in montmorillonite. Methylene blue exhibits a certain luminescence in MB-SWy samples with cation exchange capacity 0.80 meq g-1 and almost no luminescence in MB-Cheto samples with higher cation exchange capacity 1.50 meq g-1.

Structure of montmorillonite cointercalated with stearic acid and octadecylamine: modeling, diffraction, IR spectroscopy.

Structural analysis of Na-montmorillonite co-intercalated with octadecylamine and stearic acid was carried out using combination of experiment: X-ray powder diffraction and IR spectroscopy with molecular modeling (force field calculations) in Cerius(2) modeling environment. Results of structure analysis revealed the chemical reaction of guest compounds leading to the formation of octadecylammonium stearate. This reaction may occur even before the intercalation out of the interlayer space of montmorillonite. The presence of octadecylammonium stearate in the samples was clearly confirmed by IR spectroscopy and X-ray diffraction. Present results also showed that: (1) Stearic acid itself does not intercalate into Na-montmorillonite; (2) cointercalation with octadecylamine led to the formation of octadecylammonium stearate, which was successfully intercalated into the interlayer space of montmorillonite, and (3) Na-montmorillonite intercalated with octadecylammonium stearate does not create a stable structure. Intercalated samples in ambient conditions undergo gradual decomposition, accompanied by the release of octadecylammonium stearate from the interlayer space and rearrangement of the interlayer structure. Co-intercalation of STA and ODA to lower the octadecylamine content and consequently to suppress the unfavorable effect of amine groups on the polymer matrix in nanocomposite, was investigated.

Structure analysis of intercalated layer silicates: combination of molecular simulations and experiment.

Na(+)-montmorillonite type Wyoming, cloisite Na(+) from Southern Clay Products, Inc., was intercalated (i) with octadecylammonium cations and subsequently intercalated with octadecylamine molecules, (ii) with dodecylamine molecules, and (iii) with octylamine molecules to determine the applicability of these intercalates for nanocomposite materials on the base of polymer/clay. The structures were determined on the basis of a combination of results from X-ray diffraction and molecular simulations. The calculated values of basal spacings are in good agreement with experimental basal spacings when experimental samples were prepared. The interlayer space of intercalated montmorillonite shows a monolayer or bilayer arrangement of alkyl chains in dependence on the concentration of the intercalation solution. The values of the total sublimation energy, interaction energy, and exfoliation energy were calculated for all investigated samples. Low values of exfoliation energies lead to better exfoliation of intercalated silicate layers and this material appears suitable for use as a precursor for polymer/clay nanocomposites. The values of exfoliation energy for the investigated samples show that montmorillonite intercalated with dodecylamine or octadecylamine molecules is suitable for exfoliation of silicate layers.

Antigen-specific transfer factor from mice immunized with an attenuated flavivirus: augmentation of inducing activity in semipurified splenocytic dialyzates.

Three large batches were prepared of lyzed splenocytic leukocyte dialyzate from SPF outbred mice, immunized with a live attenuated virus from the tick-borne encephalitis (TBE) complex. Total mass of freeze-dried dialyzates was 1.73 g. One mg of respective batches contained 2 X 10(5), 2 X 10(4) and 2 X 10(3) units of the transfer factor, specific for the flavivirus group-antigen, as estimated according to the capacity to induce specifically cytotoxic T-cells in the recipient C3H mice. The amount of protein and orcinol-reactive material (purine-bound ribose), the presumed components of the inducer's substrate, ranged in individual dialyzates from 9.9-12.4 and 0.72-0.80% of their dry mass. Materials from each batch obtained after double precipitation by ethanol were subjected to permeation chromatography on Sephadex G-25 columns and subsequent lyophilization of the peak with specific inducing activity. The final product represented on average 3.7 per cent of dry mass of the starting material. In comparison to the crude material, in one mg of the final product the protein and the orcinol-reactive material were reduced by 80 and 37 per cent, respectively, but an increment in the antigen-specific inducing capacity comprising 2-3 log10 units was observed. These findings add to the concept that a) macromolecules carrying the inducing activity can be separated from other constituents of the crude dialyzate and b) an increase in antigen-specific inducing activity titre was, besides partial concentration, mainly due to removal of suppressor or inhibitory factor(s) present in the crude dialysates and probably acting in vivo.

Concentration of murine antigen-specific transfer factor of defined potency.

Dialysates containing transfer factor (TF) activity were prepared from lyzed splenic cells of SPF mice immunized with live, peripherally avirulent Langat virus (TP21 E5 "14" clone) from the tick-borne encephalitis (TBE) complex. The amount of TF was estimated by its capacity to generate in recipient inbred C3H mice cytotoxic T lymphocytes inducing lysis of TBE virus-infected target cells as demonstrated by 51Cr--release assay. A 100 to 1000-fold concentration of TF activity was achieved by combination of the two-step ethanol precipitation of crude dialysates with subsequent fractionation on Sephadex G-25 by exclusion chromatography. Materials from individual concentration steps showed reduced amounts of admixtures, as revealed by absorbance profiles of their chromatograms. In the final product the protein content was most decreased.

Dialysable specific transfer factor in mice immunized with attenuated Langat virus from the tick-borne encephalitis complex: generation, action and quantitative assay.

Cytolytic T lymphocyte assay was developed in order to measure the response of inbred C3H mice to dialysable specific transfer factor (STF), induced in subadult outbred mice by one shot immunization with the attenuated Langat virus. The first STF activity in mice splenic leukocytes was detected between 48-72 hr after virus administration. The conversion of splenic T-cell cytotoxic response in C3H mice in vivo occurred between 15-21 hr after STF administration. The killing activity of T-cells, induced by STF, showed cross-reactive traits within the genus Flavivirus. STF, given prior to the live virus, augmented the specific cytolytic T-cell response. In the live virus-primed mice the booster effect was markedly enhanced when administration of STF preceded the second immunization dose. In the serum of STF recipients, interferon was irregularly detected attaining low levels for short time periods. Temperature of 56 degrees C for 60 min abolished the activity of least 10(4) murine STF units, temperature of 37 degrees C lowered after 24 hr this activity by 3 log10units. Chromatography of the dialyzed leukocyte lysate on Sephadex G-25 column yielded usually five peaks. The second peak showed an increased content of ribose-bound and protein materials and, as a rule, a relatively concentrated STF activity.