Thermal ionization of excitons in V-shaped quantum wires

The exciton-to-free-carrier transition in GaAs and In_xGa_{1-x}As V-shaped quantum wires is revealed by means of temperature-dependent magnetoluminescence experiments. The experimental results are in excellent agreement with the diamagnetic shift obtained from a solution of the full two-dimensional Schrödinger equation for electrons and holes including magnetic-field and excitonic effects. In the GaAs wires, the exciton-to-free-carrier transition is found to occur at temperature consistent with the exciton binding energies. In the In_xGa_{1-x}As wires the diamagnetic shift of the luminescence is found to be free-carrier-like, independent of temperature, due to the weakening of the exciton binding energy induced by the internal piezoelectric field

The Nachtlichter app: a citizen science tool for documenting outdoor light sources in public space

The relationship between satellite based measurements of city radiance at night and the numbers and types of physical lights installed on the ground is not well understood. Here we present the "Nachtlichter app", which was developed to enable citizen scientists to classify and count light sources along street segments over large spatial scales. The project and app were co-designed: citizen scientists played key roles in the app development, testing, and recruitment, as well as in analysis of the data. In addition to describing the app itself and the data format, we provide a general overview of the project, including training materials, data cleaning, and the result of some basic data consistency checks

Laser Beam Melting of Complexly Shaped Honeycomb Structures

Laser beam melting (LBM) offers the opportunity to manufacture highly complex structures and geometries and thus provides a big potential to produce lightweight parts. In previous research projects, a software tool has been developed that achieves the placement of hexagonal honeycombs (of any size and wall thickness) on free formed surfaces in a load-oriented manner and thus offers entirely new possibilities for designing lightweight components in CAD (e.g. [1–2]). This work examines the production of metal hexagonal honeycombs from the material AlSi10Mg with the LBM-process. By adapting the exposure and process parameters, it was possible to manufacture overhanging structures with an overhang angel < 30° (relative to build platform) without support structures, while still achieving an acceptable surface roughness (in the context of this study: Ra = 45 µm). Conventional complex and time consuming post-processing steps can thus be avoided and a higher utilization of building space can be achieved. Furthermore, since the critical size for a lightweight structure is the minimum possible density, it was investigated to which minimum values the wall thicknesses of the hexagonal structures can be reduced using LBM. Apart from that, the stability of the manufactured honeycombs was analyzed in as-built condition and heat treated by pressure test and related to the honeycomb density. This has been used to compare additively manufactured honeycombs with conventionally manufactured ones

Potentials and Challenges of Multi-Material Processing by Laser-Based Powder Bed Fusion

Multi-material additive manufacturing offers a multitude of opportunities for increasing functional integration beyond the current state of the art. However, the real potential is only vaguely described and there are also challenges alongside the new opportunities. This paper presents a systematic collection of the challenges to be overcome by laser-based powder bed fusion before it can provide industrially relevant multi-material processes. Amongst others, parameter adaptation to avoid micro-cracking, relevant process monitoring technologies (e.g., thermography-based layer monitoring) and potential approaches for powder separation (e.g., using ferromagnetism) are described. Furthermore, to exploit the full potential of multi-material designs, possible concepts for the integration of fully functioning mechatronic devices into multi-material parts are also presented.Mechanical Engineerin

Thioredoxin from the Indianmeal moth Plodia interpunctella: cloning and test of the allergenic potential in mice.

BACKGROUND/OBJECTIVE: The Indianmeal moth Plodia interpunctella is a highly prevalent food pest in human dwellings, and has been shown to contain a number of allergens. So far, only one of these, the arginine kinase (Plo i 1) has been identified. OBJECTIVE: The aim of this study was to identify further allergens and characterise these in comparison to Plo i 1. METHOD: A cDNA library from whole adult P. interpunctella was screened with the serum of a patient with indoor allergy and IgE to moths, and thioredoxin was identified as an IgE-binding protein. Recombinant thioredoxin was generated in E. coli, and tested together with Plo i 1 and whole moth extracts in IgE immunoblots against a large panel of indoor allergic patients' sera. BALB/c mice were immunised with recombinant thioredoxin and Plo i 1, and antibody production, mediator release from RBL cells, T-cell proliferation and cytokine production were measured. RESULT: For the first time a thioredoxin from an animal species was identified as allergen. About 8% of the sera from patients with IgE against moth extracts reacted with recombinant P. interpunctella thioredoxin, compared to 25% reacting with recombinant Plo i 1. In immunised BALB/c mice, the recombinant allergens both induced classical Th2-biased immune responses such as induction IgE and IgG1 antibodies, upregulation of IL-5 and IL-4 and basophil degranulation. CONCLUSION: Thioredoxin from moths like Plo i 1 acts like a classical Type I allergen as do the thioredoxins from wheat or corn. This clearly supports the pan-allergen nature of thioredoxin. The designation Plo i 2 is suggested for the new P. interpunctella allergen