In Situ Hydration of Sulfoaluminate Cement Mixtures Monitored by Synchrotron X-Ray Diffraction

Mixtures of calcium sulfoaluminate and Portland clinkers with gypsum were hydrated with deionized water. The pastes were introduced in 0.7 mm borosilicate capillary tubes and kept at 40 oC while diffraction patterns were collected every 35 s for approximately 3 hours with a monochromatic radiation of 12 keV at the XRD1 beamline of the Laboratório Nacional de Luz Síncrotron (LNLS) in Campinas, SP - Brazil. The main crystalline phases (C2S, C3S, ettringite, ye’elemite and gypsum) involved in the hydration were quantified by Rietveld analysis. The most noticeable fact was the absence of portlandite as a crystalline precipitate, most likely due to the capture of calcium ions to form ettringite.

Purification of Aqueous Solutions from Salts and Radionuclides

The paper presents the technology of industrial waste purification based on the use of natural mineral bentonite sorbent with a large specific surface area, achieved by a cavitation crushing method, partially up to nanosize particles. The possibility for the purification of liquid radioactive waste (LRW) is shown by the example of floor drains with a significant content of salts, as well as organic mineral oils and surface-active substances. In addition to sorption of radionuclides, the used nanostructured sorbent has the ability to sorb heavy metals, salts, borates. The proposed technology contains several stages: ultrasonic treatment of ozonized LRW with the addition of sorbent; centrifugation or precipitation of the resulting mixture; obtaining a sorption-crystalline precipitate and condensate by evaporation. The final stage of processing — evaporation and vitrification in detail in this paper are not considered. The research presents the method of purification of actual LRW solutions for subsequent treatment with sorption-crystalline concentrate for vitrification. Coefficient of activity decrease equals to 103. The cost of technology is negligible, because it is based on the use of cheap bentonite. The proposed method can be used also for cleaning general industrial waste.

Screening of Bile Resistance and Bile Precipitation in Lactic Acid Bacteria and Bifidobacteria

A modification of the ecometric method was developed for a rapid screening of bile resistance in lactic acid bacteria and bifidobacteria. Validation of the MEM bile assay (modified ecometric method) was performed comparing the bile resistance index (RIbile) and the bile resistance ratio (R%). Most Bifidobacterium strains assayed were bile sensitive (83.3%), while only 62.1% of lactobacilli showed that behavior. Some bifidobacterial strains (55.6%) showed a crystalline precipitate when grown on solid medium supplemented with 0.5% ox bile. The crystalline structures produced by B. pseudolongum CIDCA 531 were isolated and analyzed by optical and scanning electron microscopy, thin-layer chromatography, melting point, and specific cholesterol reactions. Those studies confirmed the presence of cholesterol in these crystalline structures. On the other hand, none of the lactobacilli and streptococci studied had the ability to produce crystalline precipitates.

Synthese und Struktur von Cäsium-1,5-bis(p-tolyl)pentaazadienid, Cs+(tolN5tol)- / Synthesis and Structure of Cesium 1,5-Bis(p-tolyl)pentaazadienide, Cs+(tolN5tol)-

Cs+(tolN5tol)- (1) is formed as a yellow crystalline precipitate after addition of a concentrated aqueous solution of CsCl to a concentrated solution of 1,5-Bis(p-tolyl)pentaazadiene(1,4) in ammonia. 1 crystallizes in the orthorhombic space group Pccn with a = 3169(1), b = 434.3(2), c = 1109.4(7) pm, Z = 4. The structure contains (tolN5tol)- anions and Cs+ cations both occupying two-fold axes. The all-trans N5 zigzag chain is planar with localized double bonds N1 - N2 and N2′ - N1′ of 127.7 pm and shortened single bonds N2-N3 and N3-N2′ of 136.9 pm. The tolyl substituents are titled by 25.5° against the plane of the N atoms. Cs+ is surrounded in a square antiprismatic arrangement by eight N atoms of four N5 chains with distances Cs-N in the range of 314.6 to 366.2 pm.