Long-term monitoring of natural hydrogen superficial emissions in a brazilian cratonic environment. Sporadic large pulses versus daily periodic emissions

In many basins, hydrogen-emitting structures are now observed, but the estimation of the H₂ flow leading to their formation remains poorly constrained since all data show that the H₂ emissions are variable in space and time. We present here the data of a long-term monitoring campaign with a high density of permanent hydrogen detectors installed in 2 structures in the Minas Gerais State (Brazil). Results show that two kinds of signals are recorded, large sporadic pulses that affect the H₂ content of the soil for one or two days and smaller ones, with a daily periodicity, that last 6 h and during which the near surface soil concentration usually does not exceed 200 ppm. This last signal is very regular in frequency, less in amount, and the daily maximum happens around noon or in the early afternoon. We interpret the large pulses as evidences of a deep hydrogen flux, leaking either from a reservoir located in the subsurface, from an aquifer which is degassing or, although it seems unlikely, directly from the H₂ generation area.The time correlation between the pulse and the increase of the daily signal suggests that this last one corresponds to the slow release of the gas that has been captured by the soil during its transport towards the surface. This daily signal is most likely influenced by external factors such as atmospheric pressure and sub-surface bacterial activity. In map view, the lack of correlation between the highest hydrogen concentrations over time suggests that the soil is very heterogeneous and that preferential pathways exist. The results confirm that long-term monitoring, over a few months, is mandatory to catch a certain number of high pulses and so to have a better estimation of the real flow. Data also suggests that sensors with a large concentration range should be used (from 10 to several 10⁴ ppm). Even if quantification of leakage doesn't help to quantify the subsurface reserves, these new data allow a more precise evaluation of the quantity of H₂ released in surface by these structures, few hundred of kilo per day, and confirm the high H₂ prospectivity of this basin.     

The Influence of C60 Powders On Cultured Human Leukocytes

In order to check its possible acute toxicity, C₆₀ was incorporated into living human phagocytes. It was observed that C₆₀ has no influence on the survival of human leukocytes.     

Early effects of C60 Administration in Swiss Mice: A Preliminary Account for In Vivo C60 Toxicity.

Abstract

High amounts of micronized C₆₀ have been injected intraperitoneally into Swiss mice. Until the fourteenth day, they were still alive without any behaviour trouble. C₆₀ was well absorbed, and found localized in spleen and liver. Inside the liver, C₆₀ was     

Thermodynamic study of sulfanilamide polymorphism: (I). Monotropy of the alpha-variety

PURPOSE: Sulfanilamide was chosen as a model compound in order to gain insights on the stability hierarchy of drug polymorphs from structural and thermodynamic criteria. Despite numerous studies, disagreements remained on the reported enthalpies associated with the mutual interconvertions of the alpha-, beta-, and gamma-forms of sulfanilamide. Therefore, the unambiguous determination of these enthalpies was the purpose of this work. METHODS: Samples, free of solvent inclusions and made of only one form, were prepared, and analyzed combining X-ray powder diffraction and Differential Scanning Calorimetry (DSC). RESULTS: The enthalpy values associated with the alpha- to gamma- and beta- to gamma-transitions were found to be + 10.2 and + 10.9 J g-1, respectively. The calculated enthalpy of the beta- to alpha-transition is consistent with the experimental one (+ 1 J g-1). CONCLUSIONS: The monotropy of the alpha-form was ascertained over the explored temperature range at ordinary pressure.     

Preliminary Study of the Influence of Cubic C60 on Cultured Human Monocytes: Lack of Interleukin-1 β Secretion

Cultured human monocytes have been incubated with powdered cubic [60] fullerene. No modification has been observed with [60] fullerene when compared with negative control (monocytes alone).     

Solid state studies of the C60. 2(CH3)CCl3 solvate

At room temperature, the hexagonal C₆₀. 2(CH₃)CCl₃ solvate (a = 10.13(1) Å, c = 10.84(1) Å), made of alternating layers of C₆₀ and solvent molecules, forms with a negative excess volume, and its desolvation enthalpy is virtually the same as the sublimation enthalpy of the pure solvent. Crystallographic and calorimetric studies vs temperature indicate that hexagonal C₆₀. 2(CH₃)CCl₃ changes at 211.7 K (1.3 kJ mol⁻¹ of solvate) into an intermediate triclinic phase which transforms at 189.7 K (4.1 kJ mol⁻¹ of solvate) into another triclinic phase.A crystallographic analysis in the series of hexagonal C₆₀. 2 YCCl₃ solvates (Y = H, Cl, Br, CH₃) reveals that: (i) the change in the unit-cell volume values is due to a change in axis c whose value depends on the size of Y, (ii) the molar volume of the solvates depends linearly on the molar volume of the solvents.Ageing studies at room temperature show that C₆₀. 2(CH₃)CCl₃ loses its solvent molecules within a few days or a few months, depending on storage conditions.     

Etude du systeme AgIBiI3

The pseudo-binary system AgI-BiI₃ has been studied by differential thermal analysis (DTA) and by microcalorimetry. An eutectic point was found at 389°C for the composition BiI₃ : 85 mol.BiI₃ p.cent. Two new solid solutions have been discovered. Their existence has been confirmed by X-ray diffraction.