ALBERT

Description: ABSTRACT The technical and economic success of a CO 2 geological storage project requires the preservation of the site injectivity and integrity properties over its lifetime. Unlike conventional hydrocarbon gas injection, CO 2 injection may imply geochemical reactions between acidified pore fluids and target reservoir formations, leading to modifications of their poromechanical properties. To date, the chemical effects on the host rock mechanical behaviour are not satisfactorily taken into account in site-scale numerical models of CO 2 injection, mainly due to a lack of quantitative data. The present experimental work aims at characterizing the evolution of carbonate poromechanical properties induced by acid alteration. Unlike standard experimental approaches, the implemented alteration method induces a homogeneous dissolution pattern, which ensures reliable poromechanical measurements on altered samples. These well-controlled alteration conditions allow a proper interpretation of the test results through the macroscopic continuous approach of poromechanics. Petrophysical, geomechanical, and petroacoustic properties of outcrop carbonate samples have been measured for different levels of alteration to mimic long-term exposure to reactive brine. The obtained experimental data show clear trends of chemically induced mechanical weakening. Nuclear magnetic resonance measurements and microscanner imaging performed before and after alteration have provided complementary insights into the alteration effects at the microscopic scale.

Description: ABSTRACT Reverse-time migration is a two-way time-domain finite-frequency technique that accurately handles the propagation of complex scattered waves and produces a band-limited representation of the subsurface structure that is conventionally assumed to be linear in the contrasts in model parameters. Because of this underlying linear single-scattering assumption, most implementations of this method do not satisfy the energy conservation principle and do not optimally use illumination and model sensitivity of multiply scattered waves. Migrating multiply scattered waves requires preserving the non-linear relation between the image and perturbation of model parameters. I modify the extrapolation of source and receiver wavefields to more accurately handle multiply scattered waves. I extend the concept of the imaging condition in order to map into the subsurface structurally coherent seismic events that correspond to the interaction of both singly and multiply scattered waves. This results in an imaging process referred to here as non-linear reverse-time migration. It includes a strategy that analyses separated contributions of singly and multiply scattered waves to a final non-linear image. The goal is to provide a tool suitable for seismic interpretation and potentially migration velocity analysis that benefits from increased illumination and sensitivity from multiply scattered seismic waves. It is noteworthy that this method can migrate internal multiples, a clear advantage for imaging challenging complex subsurface features, e.g., in salt and basalt environments. The results of synthetic seismic imaging experiments, including a subsalt imaging example, illustrate the technique.

Description: Infections by multiple parasites are common in nature and may impact the evolution of host–parasite interactions. We investigated the existence of multiple infections involving the DNA virus LbFV and the Drosophila parasitoid Leptopilina boulardi . This vertically transmitted virus forces infected females to lay their eggs in already parasitized Drosophila larvae (a behavior called superparasitism), thus favoring its spread through horizontal transmission. Previous theoretical work indicated that the evolution of the level of the manipulation strongly depends on whether infected parasitoids can be re-infected or not. Here, we describe a strain of LbFV that differs from the reference strain by showing a deletion within the locus used for PCR detection. We used this polymorphism to test for the existence of multiple infections in this system. Viral strains did not differ on their vertical or horizontal transmission rates nor on the way they affect the parasitoid's phenotype, including their ability to manipulate behavior. Although already infected parasitoids were much less susceptible to new infection than uninfected ones, frequent coinfection was detected. However, following coinfection, competition between viral strains led to the rapid elimination of one strain or the other after a few generations of vertical transmission. We discuss the implications of these results for the evolution of the behavioral manipulation. Multiple infections have a major impact on the evolution of parasite virulence and more generally of parasite extended phenotype. Here we investigated the competitive outcome of multiple infections in a virus manipulating the behaviour of a parasitoid wasp. Our results suggest that competition between viral strains and the potential conflicts of interest emerging in multiply infected hosts should greatly affect the evolution of the behavioural manipulation.

Description: In this paper we study the ionospheric–magnetic disturbance during a strong magnetic storm on 5 April 2010 associated to a coronal hole. The Earth was under the influence of a high speed solar wind stream during four days, and IMF was southward during a very long period. The variation of the disturbed magnetic observations and GPS-TEC are compared with the variation of quiet days during the same month in order to obtain the characteristics of GPS-TEC and magnetic disturbances due to the coronal hole effect. We use multi-instruments as SCINDA-GPS station at Helwan, Egypt (29.86°N, 31.32°E) and ASW-MAGDAS station at Aswan, Egypt (23.59°N, 32.51°E) in the equatorial region. At the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field which strongly increases the TEC. During the recovery phase of the storm, we observe on TEC and magnetic data, the signature of the ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. It is the first time that we observe an anti-Sq circulation on magnetic data during four consecutive days associated to the high speed solar wind streams.

Description: Dibenzo-24-crown-8 is studied herein as a flexible ligand able to adopt different conformations, as well as for the complexation of mercury. The recrystallization of dibenzo-24-crown-8 (DB24C8) from dry THF gives a new polymorphic structure of this ligand. This new structure is described and compared to the literature compound. Additionally, coordination of this ligand to mercury iodide HgI 2 is studied.

Description: No investigation has yet been accomplished to screen the yttrium-doped effects on vanadium-based metal membranes. Synthesis, hydrogen permeation properties, and chemical stability of a novel palladium (Pd)-coated V 99 Y 1 alloy membrane are presented. Hydrogen permeation experiments have been performed to investigate the hydrogen transport properties through the Pd-coated V 99 Y 1 alloy membrane in the pressure range of 1.5–3.0 bar under pure hydrogen as well as H 2 -CO 2 and H 2 -CO gas mixtures at 400 °C. The maximum hydrogen permeation rate was ∼32 mL min –1 cm –2 for a 0.5 mm thick membrane under pure hydrogen. The results offer new directions in the synthesis of novel non-Pd-based metal membranes for hydrogen separation in precombustion capture applications. Synthesis, hydrogen permeation properties, and chemical stability of a novel Pd-coated V 99 Y 1 alloy membrane are described. The hydrogen flux values obtained for this new V-based alloy membrane under present conditions are higher than for pure palladium. The results open up new directions in the synthesis of novel non-Pd-based metal membranes for hydrogen separation in precombustion capture applications.

Description: ABSTRACT Magnetic surveys for geophysical interpretation will most usefully furnish estimates of the three components of the magnetic field vector. We review methods for obtaining this information based on scalar and tensor magnetic field measurements and point out the advantages of fluxgate vector measurements. Fluxgate vector magnetometers can be powerful instruments in magnetic mapping. The main problems in using fluxgate magnetometers arise from calibration errors and drift but these can be overcome using a quick and simple method of calibration. This method also has the advantage of compensating permanent and induced magnetic fields generated by the airplane. This is illustrated by a new aeromagnetic survey flown in the Vosges area (France). Measurement accuracy is shown to be similar to that obtained with scalar magnetometers. We take advantage of this accuracy to calculate in the Fourier domain other magnetic functions from the total-field anomaly, in particular, the magnetic gradient tensor is obtained without using any superconducting quantum devices. A similar approach is used to introduce a new magnetic anomaly tensor that is the equivalent of the pseudo-gravity tensor. Maps presented in the last sections serve as an example to illustrate the various functions, the goal of the paper being to obtain magnetic vector data from the observations without first postulating the detailed nature of the sources.

Description: Reaction of ( R , S )-α-terpineol with thioacetic acid in food grade n -hexane resulted into two α-terpineol thioacetate derivatives with the same molecular weight. After 5 h of reaction time, ( R , S )-α-terpineol was completely transformed and mixture analyzed by different chromatographic techniques. The aroma character of the α-terpineol thioacetates was described as exotic, sweet, blackcurrant, roasted and sulfury. Out of eight lipases and two esterases assayed, only non-immobilized Pig Liver Esterase (PLE) hydrolyzed α-terpineol thioacetates into the corresponding α-terpineol thiols. When reactions were performed in 0.2 M phosphate buffer at pH 8.0 and 30 °C with non-immobilized PLE, α-terpineol thiols were produced in an optimal yield of 88% after 24 h of reaction time. The aroma character of α-terpineol thiols was described as green, exotic and fresh grapefruit. Flavoring powders were prepared by freeze drying the α-terpineol thioacetates and α-terpineol thiols in the presence of maltodextrine. Preliminary applications shown, that these flavoring preparations could be used to improve the flavor quality of lighter cooked notes and tropical fruit aromas. Copyright © 2014 John Wiley & Sons, Ltd.

Description: This paper presents a study of the St Patrick's Day storm of 2015, with its ionospheric response at middle and low latitudes. The effects of the storm in each longitudinal sector (Asian, African, American and Pacific) are characterized using Global and Regional Electron Content (GEC and REC). At the beginning of the storm, one or two ionospheric positive storm effects are observed depending on the longitudinal zones. After the main phase of the storm, a strong decrease in ionization is observed at all longitudes, lasting several days. The American region exhibits the most remarkable increase in vertical Total Electron Content (vTEC) while in the Asian sector, the largest decrease in vTEC is observed. At low latitudes, using spectral analysis, we were able to separate the effects of the Prompt Penetration of the magnetospheric convection Electric Field (PPEF) and of the Disturbance Dynamo Electric Field (DDEF) on the basis of ground magnetic data. Concerning the PPEF, Earth's magnetic field oscillations occur simultaneously in the Asian, African and American sectors, during southward magnetization of the Bz component of the Interplanetary Magnetic Field (IMF). Concerning the DDEF, diurnal magnetic oscillations in the horizontal component H of the Earth's magnetic field exhibit a behavior that is opposed to the regular one. These diurnal oscillations are recognized to last several days in all longitudinal sectors. The observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models.