Silicon/organic hybrid heterojunction infrared photodetector operating in the telecom regime

The authors report on the fabrication of a silicon/organic heterojunction based IR photodetector. It is demonstrated that an Al/p-Si/perylene-derivative/Al heterostructure exhibits a photovoltaic effect up to 2.7 μm (0.46 eV), a value significantly lower than the bandgap of either material. Although the devices are not optimized, at room temperature a rise time of 300 ns, a responsivity of ≈0.2 mA/W with a specific detectivity of D¹ ≈ 7 × 10⁷ Jones at 1.55 μm is found. The achieved responsivity is two orders of magnitude higher compared to our previous efforts [1], [2]. It will be outlined that the photocurrent originates from an absorption mechanism involving excitation of an electron from the Si valence band into the extended LUMO state in the perylene-derivative, with possible participation of intermediate localized surface state in the organic material.The non-invasive deposition of the organic interlayer onto the Si results in compatibility with the CMOS process, making the presented approach a potential alternative to all inorganic device concepts.     

Is the activity of soluble CD14 enhanced following major trauma?

BACKGROUND: The molecule CD14 acts as a receptor for the protein-bound endotoxin (lipopolysaccharide [LPS]) complex and mediates the cellular effects of LPS. The soluble formation, sCD14, is supposed to neutralize circulating LPS (i.e., LPS antagonist) or transfer LPS effects to endothelial cells (i.e., LPS agonist). OBJECTIVE: To elucidate the release of sCD14 per se in patients with major trauma in the early posttrauma period. Our a priori hypothesis was that sCD14 release depends on the plasma LPS concentration simultaneously measured. PATIENTS: In a prospective study, 65 patients with multiple injuries (Injury Severity Score, 9-75) were enrolled. The patients were rescued by the medical helicopter service and directly admitted to our clinics. The plasma concentrations of sCD14 (enzyme immunoassay) and LPS (chromogenic limulus amebocyte lysate test) were analyzed. The first blood sample was collected immediately at the accident site. The following samples were drawn at intervals from 2 hours to daily for 2 weeks. RESULTS: Sixty-one patients survived the observation time. Immediately after trauma, their mean sCD14 level was not different from that of healthy individuals. Two hours later, a pronounced increase of sCD14 was observed and sustained throughout the observation period. Even nonsurvivors showed an increased sCD14 release, but less pronounced. In all patients, plasma LPS levels were elevated during the first 12 hours. CONCLUSIONS: Major trauma caused an increased release of sCD14. This elevation, however, was not correlated to LPS levels or to the severity of trauma (estimated by trauma scores). We found no evidence that sCD14 levels are of prognostic value regarding survival. Furthermore, the release of sCD14 did not occur in an LPS-neutralizing manner, but rendered possible an LPS-independent mechanism.     

Psychobiology of Altered States of Consciousness.

The article reviews the current knowledge regarding altered states of consciousness (ASC) (a) occurring spontaneously, (b) evoked by physical and physiological stimulation, (c) induced by psychological means, and (d) caused by diseases. The emphasis is laid on psychological and neurobiological approaches. The phenomenological analysis of the multiple ASC resulted in 4 dimensions by which they can be characterized: activation, awareness span, self-awareness, and sensory dynamics. The neurophysiological approach revealed that the different states of consciousness are mainly brought about by a compromised brain structure, transient changes in brain dynamics (disconnectivity), and neurochemical and metabolic processes. Besides these severe alterations, environmental stimuli, mental practices, and techniques of self-control can also temporarily alter brain functioning and conscious experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low thermal budget solid phase epitaxial growth of CaF2 on Si (111) substrates

As a low thermal budget processing technique, we have used in-situ rapid isothermal processing for growing epitaxial CaF₂ films on Si (111) substrates by solid phase epitaxy. Ex-situ rapid isothermal annealed films are polycrystalline in nature. Absorption of gases during ex-situ annealing inhibits solid phase epitaxial growth and highlights the importance of in-situ processing.     

Comparison between visioplasticity measurements and finite element computations for tensile tests on cold rolled perforated ferritic chromium steel P92

Finite element computations for tensile tests on cold rolled perforated sheet metals are compared to experimental tests with simultaneous visioplasticity measurements to determine requirements for the use of detailed FEM models. First, force–displacement curves and in the secondly the local strains have been compared. The obtained results show that the perforation geometry does not need to be depicted exactly in the FEM-model, an approximation with simple geometries like cylinders deliver reasonable results. Furthermore, the computed tensile test on perforated sheet metals with 2D-FEM models is more acceptable than wide-meshed 3D-models.