Nettoyage mécanique électrostatique et numérisation simultanée des deux faces de documents historiques sur papier

Cleaning the surfaces of cultural artefacts on paper is a vaguely defined procedure in conservation. In general, however, the term refers to removing from paper surfaces contaminants that are not attached to the paper. A machine-assisted treatment method has been recently developed to remove dust and biological contaminants from paper, photographic materials and textiles. It can be used to clean large stocks efficiently and without mechanical impact on the object surfaces. Contaminant removal is performed by frictionless application of an electrostatic foil. The method is limited to the removal of particles from surfaces and/or from indentations in the surface textures of papers and textiles. However, It is not suitable for removing any discolouration that has penetrated into the depth of the material, contaminants that are caked together with the surface, or in-grown biological contaminants. Hence, improvement of the visual aesthetic appearance of objects will be achieved only to a limited extent. The technology allows removal of dust contaminants from both sides, even from very delicate surfaces, while entirely keeping existing drawing and writing materials or pigment layers intact. Approximately 80 objects per hour can be processed, each having a width of one meter and a length of 1.50 meters. The system is a device which is expandable by modules, and two digitization units have been recently added to its technical equipment, digitizing both sides of each object in one cycle combined with the cleaning process. The advantages and limits of this technology will be shown by means of examples, as will be the methodology of quality management and control of the cleaning process, which has also been newly developed

Repair and stabilization in confined nanoscale systems - inorganic nanowires within single-walled carbon nanotubes

Repair is ubiquitous in biological systems, but rare in the inorganic world. We show that inorganic nanoscale systems can however possess remarkable repair and reconfiguring capabilities when subjected to extreme confinement. Confined crystallization inside single-walled carbon nanotube (SWCNT) templates is known to produce the narrowest inorganic nanowires, but little is known about the potential for repair of such nanowires once crystallized, and what can drive it. Here inorganic nanowires encapsulated within SWCNTs were seen by high-resolution transmission electron microscopy to adjust to changes in their nanotube template through atomic rearrangement at room temperature. These observations highlight nanowire repair processes, supported by theoretical modeling, that are consistent with atomic migration at fractured, ionic ends of the nanowires encouraged by long-range force fields, as well as release-blocking mechanisms where nanowire atoms bind to nanotube walls to stabilize the ruptured nanotube and allow the nanowire to reform. Such principles can inform the design of nanoscale systems with enhanced resilience. © 2012 Tsinghua University Press and Springer-Verlag Berlin Heidelberg

Mechanism of Transition-Metal Nanoparticle Catalytic Graphene Cutting

Catalytic cutting by transition-metal (TM) particles is a promising method for the synthesizing of high-quality graphene quantum dots and nanoribbons with smooth edges. Experimentally, it is observed that the cutting always results in channels with zigzag (ZZ) or armchair (AC) edges. However, the driving force that is responsible for such a cutting behavior remains a puzzle. Here, by calculating the interfacial formation energies of the TM-graphene edges with ab initio method, we show that the surface of a catalyst particle tends to be aligned along either AC or ZZ direction of the graphene lattice, and thus the cutting of graphene is guided as such. The different cutting behaviors of various catalysts are well-explained based on the competition between TM-passivated graphene edges and the etching-agent-terminated ones. Furthermore, the kinetics of graphene catalytic cutting along ZZ and AC directions, respectively, are explored at the atomic level