Characterization of Carbonaceous Materials by Correlated Electron and Optical Microscopy and Raman Microspectroscopy

Carbonaceous materials differ according to their chemical composition (types of heteroatoms), their structure and their microtexture. So, it is interesting to find methods for characterizing them. We choose to correlate data from Raman microspectroscopy, optical microscopy and transmission electron microscopy. First, we use both graphitizable or non-graphitizable reference carbon series of simple chemical composition in order to follow the structural transformation of the carbonaceous materials according to the evolution of these data throughout heat-treatment of these samples. Then, the coals of different ranks are studied. The Raman results are correlated with those from electron microscopy, particularly by plotting, for the graphitizable series, the diameter of the aromatic layers La (determined from lattice fringes and 11 dark-field) versus the specific surface of the Raman band characteristic of the defects centered at about 1350 cm-1 (ratio between surfaces of this band and the whole spectrum). For the coals, the half-maximum width of the band at about 1600 cm-1 has been plotted versus the reflectance. We conclude that the evolution of carbonaceous materials, throughout heat-treatments or natural processes, is possible only because different types of defects are progressively removed. These defects are heteroatoms, tetrahedral carbons, isolated and crosswise basic structural units or BSU (one, two or three stacked in parallel polyaromatic structures, less than 10 A in size) and defects in aromatic layers. The elimination of these defects permits the rearrangement of the BSUs and the establishment of an organization which can possibly reach the triperiodic order according to the series

Dynamic weakening and amorphization in serpentinite during laboratory earthquakes

The mechanical properties of serpentinites are key factors in our understanding of the dynamics of earthquake ruptures in subduction zones, especially intermediate-depth earthquakes. Here, we performed shear rupture experiments on natural antigorite serpentinite, which showed that friction reaches near-zero values during spontaneous dynamic rupture propagation. Rapid coseismic slip (>1 m/s), although it occurs over short distances (<1 mm), induces significant overheating of microscale asperities along the sliding surface, sufficient to produce surface amorphization and likely some melting. Antigorite dehydration occurs in the fault walls, which leaves a partially amorphized material. The water generated potentially contributes to the production of a low-viscosity pressurized melt, explaining the near-zero dynamic friction levels observed in some events. The rapid and dramatic dynamic weakening in serpentinite might be a key process facilitating the propagation of earthquakes at intermediate depths in subduction zones

Mass transport phenomena in microgravity: Preliminary results of the first MEPHISTO flight experiment

The MEPHISTO space program is the result of a cooperative effort that involves the French nuclear and space agencies (Commissariat a l'energie atomique, CEA - Centre National d'Etudes Spatiales, CNES) and the American National Aeronautics and Space Administration (NASA). The scientific studies and apparatus development were funded in the frame of the GRAMME agreement between CEA and CNES, the flight costs being taken in charge by NASA. Six flight opportunities are scheduled, with alternating French and American principal investigators. It is the purpose of this paper to briefly present MEPHISTO along with the preliminary results obtained during its first flight on USMP-1 in October 1992

Wet Chemical Method for Making Graphene-like Films from Carbon Black

Reduction of strongly oxidized carbon black by hydrazine hydrate yields water-insoluble graphene-like sheets that undergo to self-assembling in thin film on surfaces after drying. The height of a drop-casted graphene-like film was determined by atomic force microscopy (AFM) to be around 20 nm, corresponding to approximately 25 graphene-like layers. The oxidized carbon black and the corresponding reduced form were carefully characterized

Psoriatic Arthritis and Burden of Disease: Patient Perspectives from the Population-Based Multinational Assessment of Psoriasis and Psoriatic Arthritis (MAPP) Survey

Introduction: Psoriatic arthritis (PsA) is underdiagnosed and has a substantial impact on quality of life, disability, and work productivity. The population-based Multinational Assessment of Psoriasis and Psoriatic Arthritis (MAPP) survey examined the impact of PsA on patients’ activities of daily living and unmet treatment needs. Methods: This large-scale, random digit dialing, telephone survey of patients self-reporting a diagnosis of psoriasis and/or PsA was conducted in North America and Europe. Results: In all, 3426 patients participated in the survey, including 712 (21%) who identified themselves as having PsA. Over half of the patients reported severe PsA involving more than four joints. Eighty-three percent of patients with PsA visited a health-care provider within the past 12 months. Approximately one-quarter saw their primary care provider or dermatologist most often for their disease; 37% responded that their rheumatologist was the health-care provider seen most often for PsA. Patients with PsA reported a substantial impact of disease on physical function. One-third of patients with PsA reported missing work because of their disease and PsA impacted their ability to work full time. Over half of the patients with PsA (58%) reported receiving no treatment or topical therapy only, leaving their joint disease untreated. Factors associated with lack of adherence were perceived lack of efficacy and concerns about long-term safety. Conclusions: The MAPP survey confirms that PsA has a significant impact on physical function and activities of daily living. Undertreatment of PsA suggests a need for improved screening and diagnosis as well as education about treatment options and adherence

Agouti signalling protein is an inverse agonist to the wildtype and agonist to the melanic variant of the melanocortin-1 receptor in the grey squirrel (Sciurus carolinensis)

The melanocortin-1 receptor (MC1R) is a key regulator of mammalian pigmentation. Melanism in the grey squirrel is associated with an eight amino acid deletion in the mutant melanocortin-1 receptor with 24 base pair deletion (MC1RΔ24) variant. We demonstrate that the MC1RΔ24 exhibits a higher basal activity than the wildtype MC1R (MC1R-wt). We demonstrate that agouti signalling protein (ASIP) is an inverse agonist to the MC1R-wt but is an agonist to the MC1RΔ24. We conclude that the deletion in the MC1RΔ24 leads to a receptor with a high basal activity which is further activated by ASIP. This is the first report of ASIP acting as an agonist to MC1R