Climatically Accelerated Material Processes Determining the Long-Term Reliability of Light-Emitting Diodes.

LEDs (Light-Emitting Diodes) are widely applied not only in decorative illumination but also in everyday lighting in buildings, flats, public areas, and automotive fields. These application areas often mean harsh environments, for example, regarding the humidity content of the surrounding air: besides outdoor and automotive illumination, even the household use cases (kitchen, bathroom, cellar) may represent extreme temperature and humidity variations (often reaching relative humidity levels close to 100%) for these devices; thus, their reliability behaviour in such circumstances should be better understood. Thermally activated processes were studied in several previous publications, but less information is available regarding high-humidity environmental tests. Moisture and temperature ageing tests with appropriate environmental parameter settings were performed as accelerated lifetime tests to investigate not only the effect of temperature but also that of humidity on the ageing and reliability of LED packages containing RGB (red green blue) chips and phosphor-converted white (pcW) LEDs. The ageing was followed not only through monitoring optical/electrical/spectral parameters but also with material analysis. Moisture-material interaction models were proposed and set up. It was found that humidity-accelerated ageing processes are more severe than expected from previous assumptions. RGB and pcW LEDs showed strongly different behaviour.

[A rare cause of severe gastrointestinal bleeding]. / Seltene Ursache einer transfusionspflichtigen gastrointestinalen Blutung.

Upper gastrointestinal hemorrhage represents a common symptom in the internal medical practice. This Case Report depicts a severe gastrointestinal bleeding from an angiosarcoma that required multiple blood transfusion. As shown in this case, the actual cause may initially remain unclear. Repeated tissue sampling is mandatory to confirm a diagnosis and provide adequate treatment. Primary gastrointestinal angiosarcomas are extremely rare and highly aggressive malignant tumors that tend to grow multifocally and metastasise early. The only curative treatment option is radical surgery, thus an early stage diagnosis is crucial. Palliative care for metastatic angiosarkoma is currently a topic for clinical studies.