Search results for " Scanning"
showing 10 items of 988 documents
Self-Organization Pathways and Spatial Heterogeneity in Insulin Amyloid Fibril Formation
2009
At high temperature and low pH, the protein hormone insulin is highly prone to form amyloid fibrils, and for this reason it is widely used as a model system to study fibril formation mechanisms. In this work, we focused on insulin aggregation mechanisms occurring in HCl solutions (pH 1.6) at 60 degrees C. By means of in situ Thioflavin T (ThT) staining, the kinetics profiles were characterized as a function of the protein concentration, and two concurrent aggregation pathways were pointed out, being concentration dependent. In correspondence to these pathways, different morphologies of self-assembled protein molecules were detected by atomic force microscopy images also evidencing the prese…
In situ study of the sintering of a lead phosphovanadate in an Environmental Scanning Electron Microscope
2011
cited By 3; International audience; The in situ sintering of a powder of Pb3(VO4) 1.6(PO4)0.4 composition was performed in an Environmental Scanning Electron Microscope. The electric current induced by the electron beam was found to reduce the effective temperature of sintering as well as to accelerate the kinetics of shrinkage of a cluster composed of sub-micrometric grains of material. The presence of the residual current flow in the cluster during observation for in situ experiments helps to reduce the apparent sintering temperatures from 50 to 150 °C compared to conventional heating conditions without current. © 2011 Elsevier B.V. All rights reserved.
Simultaneous application of Fourier transform Raman spectroscopy and differential scanning colorimetry for the in situ investigation of phase transit…
1991
Abstract The combination of Fourier transform Raman spectroscopy with differential scanning colorimetry for the in situ investigation of phase transitions is illustrated using ammonium nitrate as an example. This method helps unambiguous characterisation of different phases by providing a simultaneous probe of thermodynamic and vibrational data.
Ultrastructure of the Interlamellar Membranes of the Nacre of the Bivalve Pteria hirundo, Determined by Immunolabelling.
2015
The current model for the ultrastructure of the interlamellar membranes of molluscan nacre imply that they consist of a core of aligned chitin fibers surrounded on both sides by acidic proteins. This model was based on observations taken on previously demineralized shells, where the original structure had disappeared. Despite other earlier claims, no direct observations exist in which the different components can be unequivocally discriminated. We have applied different labeling protocols on non-demineralized nacreous shells of the bivalve Pteria. With this method, we have revealed the disposition and nature of the different fibers of the interlamellar membranes that can be observed on the …
Preparation and evaluation of lauryl methacrylate monoliths with embedded silver nanoparticles for capillary electrochromatography
2012
In this article, capillary columns constituted by lauryl methacrylate monoliths with embedded silver nanoparticles (AgNPs) were developed and tested. Two incorporation approaches of AgNPs in monoliths were explored. The AgNPs were either photogenerated in situ during polymerization of the monolith by UV irradiation, or incorporated to the polymerization mixture (ex situ). The influence of the AgNP concentration on the morphological and chromatographic properties of the polymer matrix was investigated, and both the in situ and ex situ approaches were comparatively discussed. The morphology of the monoliths was characterized by electron microscopic techniques, and their electrochromatographic…
Solid-State Pyrolyses of Metal Phthalocyanines: A Simple Approach towards Nitrogen-Doped CNTs and Metal/Carbon Nanocables
2006
Solid-state pyrolysis of organometallic precursors has emerged as an alternative method for preparing carbon nanostructures such as carbon nanotubes (CNT) and carbon anions. The morphology of the tubes can be controlled by the nature of the precursors and the pyrolysis procedures, and micrometer long nanotubes, composed of metal carbide wires encased in a graphitic sheath. Cobalt phthalocyanine (CoPc) as well as iron phthalocyanine were pyrolyzed at different temperatures to obtain CNTs. HRTEM and energy-dispersion X-Ray analysis disclosed that the core consisted of long, iron-containing single crystals and that the core was fully surrounded by crystallized graphic carbon. Iron-filled carbo…
Survival of fish-virulent strains ofPhotobacterium damselaesubsp.damselaein seawater under starvation conditions
1998
The survival of fish-virulent strains of Photobacterium damselae subsp. damselae in seawater microcosms, with and without sediment, was investigated. The strains survived as culturable bacteria at 14 and 22 degrees C for at least 1 year, and infectivity for fish was maintained. At 5 degrees C, cells lost culturability on solid media, but this was recovered when the temperature was increased to 22 degrees C. Finally, morphological changes in the bacterium (rod to coccus), and production of vesicles and extracellular material were observed during the time of starvation. The overall results suggest that seawater and sediment can act as reservoirs for these virulent strains.
Computational methodologies applied to Protein-Protein Interactions for molecular insights in Medicinal Chemistry
2021
In living systems, proteins usually team up into “molecular machinery” implementing several protein-to-protein physical contacts – or protein-protein interactions (PPIs) – to exert biological effects at both cellular and systems levels. Deregulations of protein-protein contacts have been associated with a huge number of diseases in a wide range of medical areas, such as oncology, cancer immunotherapy, infectious diseases, neurological disorders, heart failure, inflammation and oxidative stress. PPIs are very complex and usually characterised by specific shape, size and complementarity. The protein interfaces are generally large, broad and shallow, and frequently protein-protein contacts are…
4,4′‐Distyrylazobenzol als Mesogen
1992
4,4′-Distyrylazobenzene as Mesogen From 3,4-dihydroxybenzaldehyde (1) the tetraalkoxy-substituted 4,4′-distyrylazobenzenes (E,E,E)-5a – c are synthesized. A similar reaction sequence leads from ethyl 3,4,5-trihydroxy-benzoate (6) to the hexaalkoxy-substituted 4,4′-distyrylazobenzenes (E,E,E)-11 b, c. With the exception of 5a all products show thermotropic LC properties. Smectic phases have been characterized by polarizing microscopy and by differential scanning calorimetry.
Cooperative Spin‐Crossover Behaviour in Polymeric 1D Fe II Coordination Compounds: [{Fe(tba) 3 }X 2 ]· n H 2 O
2007
A new family of 1D cooperative spin-crossover polymers with general formula [{Fe(tba)3}X2]·nH2O [tba = N-(4H-1,2,4-triazol-4-yl)benzamide; X = CF3SO3–, n = 2 (1), n = 0 (4); BF4–,n = 3 (2), n = 0 (5); 4-CH3C6H4SO3–, n = 3 (3), n = 0 (6)] has been synthesised and characterised using a series of spectroscopic methods, X-ray powder diffraction, magnetic susceptibility measurements and differential scanning calorimetry. The copper analogue of 1, [{Cu(tba)3}(CF3SO3)2]·3H2O (7), has also been synthesised and its crystal structure solved at 293 K. Compound 7 crystallises in the P space group. The bidentate N-(4H-1,2,4-triazol-4-yl)benzamide ligand bridges the copper ions through the 1,2-nitrogen p…