Separation of strontium from low level radioactive waste solutions using hydrous manganese dioxide composite materials

⁹⁰Sr is one of the major isotopes present in the low level radioactive liquid waste (LLW) generated during operation of nuclear reactors and spent fuel reprocessing plants. A composite ion exchange material consisting of hydrous manganese oxide and poly methyl methacrylate (PMMA) was developed for removal of strontium from aqueous radioactive waste. The prepared composite material showed very good strontium adsorption properties in aqueous solutions. Sorption of strontium on the composite material as a function of pH, equilibration time and strontium ion concentrations were studied. The process of sorption of strontium from solution was analysed using different isotherm models like Langmuir, D-R and Freundlich. Four different error functions were employed to find out the most suitable isotherm model to represent the experimental data and it was found that Freundlich model best fits the sorption of strontium on the composite material. Analysis of the data obtained from the sorption kinetics studies showed that the data fitted better to the pseudo-second order kinetic model. Lab scale column performance study of the composite material revealed that the material could be effectively used in column operations to remove strontium from LLW solutions.     

Iron compounds electrodeposited onto a transparent semiconductor: Synthesis and characterisation by UV-vis spectroscopy

Homogeneous thin layers of lepidocrocite, green rust incorporating chloride anions (GRCl-GR1) and green rust incorporating sulphate anions (GRSO₄-GR2) were successfully electrodeposited onto tin dioxide substrate (SnO₂). The UV-vis spectroscopy absorbance, measured just after synthesis, increases linearly with the amount of iron compounds confirming that the electrodeposition is a homogeneous process. From the spectra, the absorption coefficients were determined for the three compounds. The monitoring by UV-vis spectroscopy measurements in real time of the oxidation in the air of the two unstable compounds, GRCl and GRSO₄, shows that the two green rusts have a different behaviour due to their own structure. The presence of an isobestic point in the case of GRSO₄ translates one equilibrium with its oxidised compound. This phenomenon is not observed for GRCl, however, the characteristic variation of the absorbance in the high wavelengths gives information on its oxidation reaction. From simple measurements, fruitful information on green rusts is obtained and this experimental system may be applied to other unstable solid compounds.     

Cost-Effective Allocation of Research Funds for Emerging Technologies

Developers of emerging technologies, and the agencies who fund them, need an alternative to traditional cost-based risk prediction methods to help them predict how the costs of their technologies might change under future deployment scenarios. Often the only data available for predicting risk are the limited but complex data generated by field testing emerging technologies in the prototype phase of development. This paper presents a conceptual framework for evaluating cost and performance constraints of emerging technologies; the framework can be used to prioritize the allocation of research and development funds for the development of such technologies.     

A modular and parameterized presentation of pregroup calculus

The concept of pregroup was introduced by Lambek for natural language analysis, with a close link to non-commutative linear logic. We reformulate the pregroup calculus so as to extend it by composition with other logics and calculi. The cut elimination property and the decidability property of the sequent calculus proposed in the article are shown. Properties of composed calculi are also discussed.     

Effect of boron on the structural and electrochemical properties of nanocrystalline Ti2RuFeBx electrodes

The effect of the boron content on the structural and electrochemical properties of nanocrystalline Ti₂RuFeB_x (with x varying from 0 to 12) was studied. The nanocrystalline materials were prepared by high energy ball milling and their structural evolution was analyzed by X-ray and neutron diffraction. Through a detailed Rietveld refinement analysis of the structural data, it is shown that the nanocrystalline materials are mainly composed of a B2 structure at low boron content (0 < x < 2). At higher boron content, TiB₂ is mainly formed and the B2 structure disappears with the concurrent formation of a highly disordered Ru-rich phase. These electrodes were tested for the hydrogen evolution reaction in both NaOH and chlorate solutions. The best results are obtained for 4 ≤ x ≤ 6, with a cathodic overpotential at −250 mA/cm², η₂₅₀, of ∼−575 mV. Accelerated aging tests and continuous electrolysis tests show that η₂₅₀ does not vary with time, contrary to the case of Ti₂RuFe, which shows a rapid deterioration of the cathodic overpotential after a few hours of continuous electrolysis. This is explained by the lower solubility of hydrogen in Ti₂RuFeB₄ as opposed to Ti₂RuFe.     

Shaping cocaine abstinence by successive approximation.

Cocaine-using methadone-maintenance patients were randomized to standard contingency management (abstinence group, n?=?49) or to a contingency designed to increase contact with reinforcers (shaping group, n?=?46). For 8 weeks, both groups earned escalating-value vouchers based on thrice-weekly urinalyses: The abstinence group earned vouchers for cocaine-negative urines only; the shaping group earned vouchers for each urine specimen with a 25% or more decrease in cocaine metabolite (first 3 weeks) and then for negative urines only (last 5 weeks). Cocaine use was lower in the shaping group, but only in the last 5 weeks, when the response requirement was identical. Thus, the shaping contingency appeared to better prepare patients for abstinence. A 2nd phase of the study showed that abstinence induced by escalating-value vouchers can be maintained by a nonescalating schedule, suggesting that contingency management can be practical as a maintenance treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In vitro degradation of 10 mono‐ and sesquiterpenes of plant origin by caprine rumen micro‐organisms

The extent of disappearance of 10 mono‐ and sesquiterpenes in presence of mixed rumen micro‐organisms has been measured in 24‐h batch cultures. The molecules that were tested are frequently found in the plants consumed by ruminants in highland pastures (limonene, β‐myrcene, β‐ocimene, α‐pinene, sabinene, γ‐terpinene and thymol) or are potential markers of the diet (camphene, β‐caryophyllene and α‐copaene). All terpenes were tested at 2 µL mL^?1, except α‐copaene and thymol, which were tested at 0.9 µL mL^?1 and 2 mg mL^?1, respectively. Camphene and thymol were not degraded to a significant extent. The disappearance of part of β‐caryophyllene, (?)‐limonene and γ‐terpinene could not be attributed to the direct action of rumen micro‐organisms but rather than to an effect of the extracellular medium. In contrast, a third group of one sesquiterpene (α‐copaene) and four monoterpenes (myrcene, β‐ocimene, α‐pinene and sabinene) was extensively degraded by rumen micro‐organisms, at rates of 1.6, 4.5, 3.5, 4.8 and 5.4 µmol mL^?1 inoculum day^?1, respectively. The preliminary exposure of rumen micro‐organisms to a specific blend of essential oils compounds, containing mainly thymol, guajacol and limonene, increased the extent of disappearance of γ‐terpinene only. Copyright © 2007 Society of Chemical Industry     

L'organisation cognitive du système d'attachement des adolescents et leurs perceptions de l'encadrement dyadique en tutorat.

Examined the relationships between adolescents' attachment, cognitive organization, and their perceptions of control and support in an academic mentoring relationship. 98 students involved in a volunteer mentoring program were interviewed using the Adult Attachment Interview (AAI). Perceptions of security and control in the mentor-student relationship and perceptions of the program effectiveness were also assessed at the end of the program and 4 mo later. Results show that both adolescents' dismissing and preoccupied strategies in the AAI were negatively associated with their interpersonal perceptions of the mentoring experience. Some of these relationships were moderated by the sex of the dyad (same-sex vs opposite-sex). These findings are discussed in light of theoretical postulates of attachment theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Up-“Routing” Communities: Subaltern Voices Challenge Sustainable Urban Renewal in Fortaleza,Brazil

Passed in 2001, Brazil’s Estatuto da Cidade (City Statute) requires municipalities to recognize the social value of space in addition to its economic value and has been hailed as a major protection for residents of informal settlements. As Brazil was thrust onto a global stage as host to the World Cup of Soccer and 2016 Summer Olympics, how are local government city officials balancing economic and social use amidst major urban renewal processes? Drawing upon voices of informal settlement residents in Fortaleza, Brazil, we examine the impact of transportation infrastructure upgrades on informal settlements. We find that despite the right to the city espoused in the Estatuto da Cidade, residents in informal settlements continue to be socially and physically marginalized. We examine why social use protections are not halting the displacement of informal settlements and discuss emerging landscapes of local activism resulting from this contradiction.     

Dynamic mechanical analysis of novel composites from commingled polypropylene fiber and banana fiber

Polypropylene (PP)/banana fiber (BF) composites were fabricated from PP fiber and short BF by novel commingling method. The dynamic mechanical analysis (DMA) of the composites was performed with reference to BF loading and fiber surface treatments. By the incorporation of BF into the PP matrix, the storage modulus and loss modulus have been found to increase, whereas damping factor has been found to decrease. Glass transition temperature was found to increase with increase in BF loading. The viscoelastic properties of the composites were also found to depend on fiber surface treatments. The activation energy of the composites for the glass transition has been found to be increased by the increase in BF loading. Surface treatment of the BF further increased the activation energy of the composites, indicating a stronger interface for treated fiber composites. Scanning electron microscopy (SEM) photographs of the BF showed the physical changes induced by the surface treatments. Fourier transform infrared spectroscopy (FTIR) was used to ascertain the existence of the type of interfacial bonds. The use of theoretical equations to predict the storage modulus has also been discussed. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers