Assessment of biogas potential hazards

Biogas produced from anaerobic fermentation of organic substances represents an alternative renewable energy source. Its utilization would contribute to substantial reduction of the solid waste volume in land-filling and incineration. Biogas so produced could be utilized on site or it could be injected into the natural gas distribution network. Microbiological and chemical compositions of different biogas types were determined in order to conduct qualitative and quantitative risk assessments of the potential health hazards associated with biogas use for cooking. Biogas types that could be allowed for injection in the natural gas pipelines were listed with recommendations, while outlining the European biogas injection policy. Results indicated that the injection of the processed biogas in the distribution network did not present any additional chemical or microbiological risk to consumers when compared to natural gas, provided that the biogas resulted from the fermentation of non-dangerous waste. However, since this study did not examine the microbiological and chemical composition of biogas originating from wastewater sludges and/or industrial wastes, the injection of this type of biogas into the gas distribution network should not be allowed unless a similar risk evaluation study is conducted for each case.     

Lithium conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 obtained via solution chemistry

NaSICON-type lithium conductor Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is synthesized with controlled grain size and composition using solution chemistry. After thermal treatment at 850 °C, sub-micronic crystallized powders with high purity are obtained. They are converted into ceramic through Spark Plasma Sintering at 850–1000 °C. By varying the processing parameters, pellet with conductivities up to 1.6 × 10^?4 S/cm with density of 97% of the theoretical density have been obtained. XRD, FEG-SEM, ac-impedance and Vickers indentation were used to characterize the products. The influence of sintering parameters on pellet composition, microstructure and conductivity is discussed in addition to the analysis of the mechanical behavior of the grains interfaces.     

Preparation of transparent PMMA/Fe(IO3)3 nanocomposite films from microemulsion polymerization

Polymethyl methacrylate (PMMA)/Fe(IO₃)₃ nanocomposite thin films are obtained by in situ particle generation in microemulsions and subsequent photopolymerization of a mixture containing methyl methacrylate, trimethylolpropane triacrylate, and crystallized iron iodate (Fe(IO₃)₃) nanorods. Hyper‐Rayleigh scattering measurements combined with X‐ray diffraction, transmission electron microscopy, and dynamic light scattering are first used to probe in situ the crystallization kinetics of iron iodate nanorods in water‐in‐oil microemulsions prepared with methyl methacrylate as the oil phase and marlophen NP12 as a surfactant. Trimethylolpropane triacrylate is then added as a crosslinker before spin‐coating. Films are deposited on glass substrates for the nonlinear optical characterizations and on silicon wafers for the piezoelectric and mechanical measurements. Nanocomposite films treated by corona discharge are finally characterized through optical microscopy, laser Doppler vibrometry, and Brillouin spectroscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1203‐1211, 2013     

Chemical stimulation techniques for geothermal wells: experiments on the three-well EGS system at Soultz-sous-Forêts,France

Rock matrix stimulation is a method of enhancing well production or injection within a broad range of challenging environments, varying from naturally fractured limestones to sandstones with complex mineralogy. A common and often successful stimulation option, matrix acidizing, utilizes acids that react and remove mineral phases restricting fluid flow. Reviewed is the technology of chemical treatments available for oil, gas and geothermal wells and the key elements and results of the chemical reservoir stimulation program at the Soultz-sous-Forêts, France, Enhanced Geothermal System Project.     

Thermoreversible gelation of poly[hexyl isocyanate]: Effect of solvent type

The thermoreversible gelation of poly[hexyl isocyanate] (PHIC), a rather stiff polymer, has been studied in two closely-related solvents of the alcane series, namely heptane and octane. Temperature-concentrations phase diagrams have been established for both systems. The occurrence of polymer-solvent compound is suggested in heptane but not in octane. This conclusion receives further support from neutron diffraction investigations through the use of the isotopic labelling technique. Finally, it is observed that the morphology is also affected by the solvent type although still displaying a fibrillar network structure.     

How to monitor the modulus of elasticity of concrete,automatically since the earliest age?

Monitoring the evolution of an early age set of parameters on concrete is necessary to predict the early age behaviour of structures. The difficulty lies in the fact that this monitoring must be automatic because the concrete hardening process takes place over a long period after the casting. This paper presents a new methodology and an apparatus, specifically designed at IFSTTAR, to monitor the hardening process of a concrete. Mainly, the Young’s modulus can be monitored in compression. Measurements start soon after having cast the concrete and the sample temperature is completely controlled so that the concrete maturity is well mastered. The performances of this apparatus, obtained on an ordinary concrete, are compared to more classical measurements using an extensometer mounted on the sample just after the setting time and to ultrasonic measurements. In these cases, the temperatures were not controlled and results have to be expressed in equivalent time. A comparison with another method developed and used at ULB by using the same concrete, in the frame of a joined cooperation between our two laboratories is achieved. This test set up is based on the so called Temperature Stress Testing Machine (TSTM). This device has been specifically designed with a control of the concrete maturity by the use of a dummy specimen only submitted to free deformations (thermal, shrinkage). The TSTM allows compressive and tensile testing starting just after the setting time. In addition, concrete properties, such as compressive and tensile strength, have been characterized at early age. These values have been used for the design of the loading histories applied in the automatic tests. The heat released by the cement hydration has also been measured in order to express the results on a maturity scale.     

Tensile basic creep versus compressive basic creep at early ages: comparison between normal strength concrete and a very high strength fibre reinforced concrete

The paper presents experimental results concerning the comparison of tensile and compressive basic creep behaviours at early ages of two different concretes: a normal strength concrete (NSC) and a very high strength fibre reinforced concrete (HPFRC). This research project has been done in the context of a bilateral collaboration between Polytechnique Montreal and IFSTTAR. Observations on the HPFRC showed specific compressive creep similar to the specific tensile creep. Moreover, the specific creep curves obtained under compressive and tensile loading had always positive values, i.e. they were in same direction of the applied load on specimens. Measurements made on the NSC revealed specific compressive creep with positive values (in the loading direction). However, specific tensile creep presented negative values (opposite direction of loading) for a long period. A physical explanation based on the existence of two mechanisms with opposite effect is proposed to describe these basic creep results. The first mechanism is a coupling between the microcracking process and the water transfers that lead to additional self-drying shrinkage; the second mechanism is the self-healing of concrete induced by the microcracking.     

Nebulized Gadolinium‐Based Nanoparticles: A Theranostic Approach for Lung Tumor Imaging and Radiosensitization

Lung cancer is the most common and most fatal cancer worldwide. Thus, improving early diagnosis and therapy is necessary. Previously, gadolinium‐based ultra‐small rigid platforms (USRPs) were developed to serve as multimodal imaging probes and as radiosensitizing agents. In addition, it was demonstrated that USRPs can be detected in the lungs using ultrashort echo‐time magnetic resonance imaging (UTE‐MRI) and fluorescence imaging after intrapulmonary administration in healthy animals. The goal of the present study is to evaluate their theranostic properties in mice with bioluminescent orthotopic lung cancer, after intrapulmonary nebulization or conventional intravenous administration. It is found that lung tumors can be detected non‐invasively using fluorescence tomography or UTE‐MRI after nebulization of USRPs, and this is confirmed by histological analysis of the lung sections. The deposition of USRPs around the tumor nodules is sufficient to generate a radiosensitizing effect when the mice are subjected to a single dose of 10 Gy conventional radiation one day after inhalation (mean survival time of 112 days versus 77 days for irradiated mice without USRPs treatment). No apparent systemic toxicity or induction of inflammation is observed. These results demonstrate the theranostic properties of USRPs for the multimodal detection of lung tumors and improved radiotherapy after nebulization.     

Ageing of V2O5 thin films induced by Li intercalation multi-cycling

Cyclic voltammetry, XPS, RBS and AFM have been combined to study the ageing mechanism of Li intercalation in V₂O₅ thin films prepared by thermal oxidation of vanadium metal. Multi-cycling tests were performed in 1 M LiClO₄-PC in the potential range E ∈ [3.8, 2.8 V] versus Li/Li⁺, corresponding to the α-to-δ phase transition. XPS and AFM were performed using direct anaerobic and anhydrous transfer. Capacity fading remains inferior to 20% during ∼2500 cycles. XPS shows slight modifications of the oxide composition with a V⁴⁺ concentration increasing from ∼5% prior to cycling to ∼16–27% after cycling, due to Li trapped in the oxide film and to the loss of V₂O₅ active material. The presence of lithium carbonate and lithium-alkyl carbonate species evidences the formation of the so-called SEI layer. AFM evidences the loss of crystalline material by grain exfoliation from the outer V₂O₅ layer of the oxide film. By further exfoliation, the inner VO₂ layer of the oxide film is reached and pits are formed, occupying ∼9–13% of the surface. This de-cohesion at grain boundaries is attributed to the strain generated by repeated lattice distortions. After 3300 cycles, the disappearance of lithium carbonates, whereas Li-alkyl carbonates and/or Li-alkoxides remain on the surface, indicates the dissolution and/or conversion of the SEI layer. After 4500 cycles, the oxide film became very labile and could be stripped away by rinsing to reveal the vanadium metal substrate.