Effect of Fines Content on the Cyclic Undrained Behavior of Sand

The influence of fines on the liquefaction potential of sandy soils has been studied by conducting isotropically consolidated stress controlled triaxial tests. Experimental results are compared with predictions using the theory developed by Nasser and Shokooh which is based on energy considerations. The theory determines the excess pore water pressure in terms of the number of cycles N, the dimensionless shear stress amplitude, and the initial and minimum values of the void ratio. The comparisons show good agreement between experimental data and model predictions for the pore water generation under cyclic loading for both loose and medium sands and medium silty soils

Sorption Studies of Cs+ and Ba2+ Cations on Magnesite

Cataloged from PDF version of article.The adsorption behavior of Cs+ and Ba2+ cations on magnesite has been studied as a function of time, cation concentration and temperature, utilizing both the radiotracer method and X-ray photoelectron spectroscopy (XPS). Saturation was approached in about I day for both cations. The sorption data were found to follow Freundlich type isotherms. Sorption of both Cs+ and Ba2+ cations were found to be exothermic in nature with ΔH0 (kJ/mol) of -37, -13 and ΔS0 (kJ/mol·K) of -0.09, -0.009, respectively. Negative ΔG0 values were obtained for both cations, indicating the spontaneity of their sorption on magnesite. The magnitude of ΔG0 suggest that ion exchange is the dominating sorption mechanism. The adsorption behavior of Cs+ and Ba2+ cations on magnesite has been studied as a function of time, cation concentration and temperature, utilizing both the radiotracer method and X-ray photoelectron spectroscopy (XPS). Saturation was approached in about 1 day for both cations. The sorption data were found to follow Freundlich type isotherms. Sorption of both Cs+ and Ba2+ cations were found to be exothermic in nature with ΔH0 (kJ/mol) of -37, -13 and ΔS0 (kJ/mol·K) of -0.09, -0.009, respectively. Negative ΔG0 values were obtained for both cations, indicating the spontaneity of their sorption on magnesite. The magnitude of ΔG0 suggest that ion exchange is the dominating sorption mechanism

A Radiotracer study of the adsorption behaviour of aqueous Ba2+ ions on nonoparticles of zero-valent iron

Cataloged from PDF version of article.Recently, iron nanoparticles are increasingly being tested as adsorbents for various types of organic and inorganic pollutants. In this study, nanoparticles of zero-valent iron (NZVI) synthesized under atmospheric conditions were employed for the removal of Ba2+ ions in a concentration range 10-3 to 10-6 M. Throughout the study, 133Ba was used as a tracer to study the effects of time, concentration, and temperature. The obtained data was analyzed using various kinetic models and adsorption isotherms. Pseudo-second-order kinetics and Dubinin-Radushkevich isotherm model provided the best correlation with the obtained data. Observed thermodynamic parameters showed that the process is exothermic and hence enthalpy-driven. © 2007 Elsevier B.V. All rights reserved

Evolution of fermenting microbiota in tarhana produced under controlled technological conditions

The purpose of this study was to evaluate the evolution of lactic acid bacteria (LAB) and yeasts during the fermentation of tarhana produced with some pasteurised ingredients and carried out at 30 and 40 C. The chemical parameters were those typical for tarhana production. Coliform bacteria were not detected during fermentation, while LAB and yeasts were in the range 107e108 colony forming units (CFU) g 1. Plate counts showed an optimal development of both fermenting microbial groups and the differences in cell concentrations were not significant (P > 0.05). LAB were isolated during fermentation and grouped on the basis of phenotypic and polymorphic characteristics. LAB isolates were identified by a combined genetic approach consisting of 16S/23S rRNA intergenic spacer region (ITS) and partial 16S rRNA gene sequencing as Pediococcus acidilactici, Lactobacillus plantarum and Lactobacillus brevis. Hence, the pas- teurisation of the vegetable ingredients, excluded wheat flour, enhanced the hygienic conditions of tarhana without influencing the normal evolution of LAB. However, the fermentation at 40 C favoured pediococci, while the production at 30 C was mainly characterised by lactobacilli. Yeasts, identified by the restriction fragment length polymorphism (RFLP) of the 5.8S ITS rRNA gene, were mainly represented by the species Saccharomyces cerevisiae in both productions

Screening Non-Saccharomyces Yeasts as Low Ethanol Producing Starter Cultures

Non-Saccharomyces yeasts are known for their low fermentation rate in comparison to Saccharomyces cerevisiae.  In this study, non-Saccharomyces yeasts were inoculated into Chenin blanc grape must and fermented under aerobic and anaerobic conditions.  Saccharomycodes ludwigii displayed a strain-dependent fermentation rate, which yielded between 5.2% and 9.9% ethanol concentration under both conditions, albeit with residual sugar.  Aerobic conditions favoured the production of reduced ethanol which was between 5.8% and 9.7% for non-Saccharomyces yeasts in comparison to S. cerevisiae (10%).  This trend was observed for Wickerhamomyces anomalus, Stamerella bacillaris (Candida zemplinina), Metshnikowia pulcherrima, Cyberlindnera saturnus, Wickerhamomyces subpelliculosus and Cyberlindnera jadinii.  The laboratory-scale wines prepared with the aforementioned yeasts yielded ripe fruit and floral aroma attributes while other non-Saccharomyces yeasts resulted in wines with spicy, acidic and solvent aroma notes

Synthesis and spectral studies of 5-[3-(1,2,4-triazolyl-azo]-2,4-dihydroxybenzaldehyde(TA)and its Schiff bases with 1,3-diaminopropane(TAAP)and 1,6-diaminohexane(TAAH).Their analytical application for spectrophotometric microdetermination of cobalt(II).

Cataloged from PDF version of article.The new azo compound 5-[3-(1,2,4-triazolyl-azo]-2,4-dihydroxy-benzaldehyde (TA) and its Schiff bases with 1,3-diaminopropane (TAAP) and 1,6-diaminohexane (TAAH) have been synthesized. The bands of diagnostic importance in the IR and the main signals in 1 H NMR spectra are assigned. The electronic absorption spectra in pure organic solvents of different polarity and in buffer solutions of varying pH are investigated. The quantitative description of the solvent effect on the electronic absorption spectra is studied and their acid ionization constants are determined. Also, a new simple and sensitive method for the spectrophotometric microdetermination of Co(II) using these compounds (TA, TAAP and TAAH) as new chromogenic reagents is established. The developed method is successfully used for the determination of trace amounts of cobalt in authentic samples and calculation of the distribution ratio of cobalt adsorbed on bentonite and kaolinite clay minerals. 2004 Elsevier Ltd. All rights reserved

Sorption Studies of Radioiodine on Soils with Special References to Soil Microbial Biomass

In batch experiments with two types of soils, chernozem and podzol, radioiodine (125I) showed an initial rapid sorption, followed by a long and slow further increase. Very little sorption (Rd < 1) was detected in clay minerals. Generally, higher. Revalues were observed for the chernozem soil, characterized by a higher amount of organic substance and of soil biomass. The sorption process was predominantly irreversible, the isotherms were linear at low ion concentrations and deviated from linearity starting at 10-5 mmol - ml-1. Sorption ratio was found to increase with increasing volume to mass ratio. The composition of liquid phases (bidistilled water, synthetic soil water, rain water) highly affected iodine sorption. In experiments with KBr solution, the sorption of I “ was found to be strongly preferred to Br”. Incubation of soil samples under varied conditions (decreased or increased soil biomass, 02-concentration, incubation temperature, soil water content and storage conditions) delivered indications for the participation of soil microflora in iodine immobilization. Test with isolated soil bacteria and fungi showed that radioiodine can be incorporated by soil microorganisms under certain conditions only: Considerable uptake of radioiodine was found in washed (NaCl, CaCl2) cells with both bacteria and fungi, but no incorporation was detected into cells incubated with radioiodine in the culture medium. © 1991, Walter de Gruyter. All rights reserved

Migration Behaviour of Barium and Strontium through Colemanite

Column and batch experiments were performed to study the migration behaviour of Ba and Sr in colemanite matrix. 133Ba. 90Sr and 3H were used as tracers. The retardation factors and the distribution ratios of Ba and Sr in column experiments were found to be smaller than those obtained in batch experiments. Sorption Ra values of Ba were higher than those of Sr determined by both techniques. Sorption energies calculated from batch experiments are in good agreement with the literature values

Sorption of barium on kaolinite, montmorillonite and chlorite

The sorption characteristics of the Ba2+ ion on kaolinite, montmorillonite and chloritetype clays were studied using the batch method. Barium-133 was used as a tracer. The Ba2+ ion concentrations ranged from 10-8 to 10-5 mol l-1; synthetic groundwater was used and the grain size of all the solid particles was <40 μm. About 6, 8 and 12 d of shaking were necessary to reach equilibrium for chlorite, kaolinite and montmorillonite, respectively. The sorption isotherms were described best by Freundlich and Dubinin - Radushkevich type isotherms. Sorption was predominantly reversible for kaolinite and partly reversible for montmorillonite and chlorite