We characterized the energy band dispersion near the Fermi level in single-walled carbon nanotubes using low-temperature scanning tunneling microscopy. Analysis of energy-dependent standing wave oscillations, which result from quantum interference of electrons resonantly scattered by defects, yields a linear energy dispersion near E(F), and indicates the importance of parity in scattering for armchair single-walled carbon nanotubes. Additionally, these data provide values of the tight-binding overlap integral and Fermi wave vector, in good agreement with previous work, but indicate that the electron coherence length is substantially shortened.
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Sandwich panels and beams are used in bending and compression dominated components. The retention of their load capacity in the presence of imperfections is a central consideration. To address this issue, sandwich beams with metallic foam cores have been tested in four-point bending following the introduction of imperfections, created by impressing the face sheets. Limit load expressions for face yielding, core shear, and indentation failure have been developed and used to construct failure mechanism maps. From these maps, specimen designs were determined. Imperfections were introduced by indenting to varying penetrations. The indents were located on both the compressive and tensile side of bending configurations. Experimental measurements of the load/deflection response are obtained and compared with finite element results.
Along with the process of the epidemiological transition, northern Finland has experienced an increase of cardiovascular diseases, some types of cancer, and accidental and suicidal deaths, particularly in the male population, while the females of northern Finland have shown rather favourable trends during the post-war period. Northern Finland shows a clustering of severe health problems such as coronary heart disease, accidents and suicides in smaller areas, e.g. in north-central Lapland, which records mortality rates 2-3 times higher than areas of lowest mortality. There is some indication of a high prevalence of smoking, increased serum lipids, blood pressure, body weight and alcohol consumption in the areas of highest morbidity and mortality, but evidence based on representative population samples is missing. Accidents and suicides are also common in the Sâmi (Lapp) area but coronary heart disease is rare, despite the unfavourable risk factor patterns.
Complex, optically functional surfaces in organic polymers can be fabricated by replicating relief structures present on the surface of an elastomeric master with an ultraviolet or thermally curable organic polymer, while the master is deformed by compression, bending, or stretching. The versatility of this procedure for fabricating surfaces with complex, micrometer- and submicrometer-scale patterns was demonstrated by the production of (i) diffraction gratings with periods smaller than the original grating; (ii) chirped, blazed diffraction gratings (where the period of a chirped grating changes continuously with position) on planar and curved surfaces; (iii) patterned microfeatures on the surfaces of approximately hemispherical objects (for example, an optical surface similar to a fly's eye); and (iv) arrays of rhombic microlenses. These topologically complex, micropatterned surfaces are difficult to fabricate with other techniques.
Nanoscale electromechanical systems-nanotweezers-based on carbon nanotubes have been developed for manipulation and interrogation of nanostructures. Electrically conducting and mechanically robust carbon nanotubes were attached to independent electrodes fabricated on pulled glass micropipettes. Voltages applied to the electrodes closed and opened the free ends of the nanotubes, and this electromechanical response was simulated quantitatively using known nanotweezer structure and nanotube properties. The mechanical capabilities of the nanotweezers were demonstrated by grabbing and manipulating submicron clusters and nanowires. The conducting nanotube arms of the tweezers were also used for measuring the electrical properties of silicon carbide nanoclusters and gallium arsenide nanowires.
The Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) derived no-effect level (DNEL) is defined by the European Chemicals Agency (ECHA) as “… the level of exposure above which humans should not be exposed.” DNELs are derived for substances (i.e., chemicals and mixtures) that exhibit a threshold dose–response relationship. Based on the available, relevant health hazard data, substance-specific DNELs can be derived for both the worker and general populations (including consumers). The starting point for DNEL derivation is usually a no observed adverse effect level (NOAEL), lowest observed adverse effect level (LOAEL), or benchmark dose (BMD) from experimental animal studies. ECHA has developed extensive guidance on the DNEL derivation process. DNELs are used in REACH risk characterization process for REACH-regulated substances.
