Matrix Transformation in Boron Containing High-Temperature Co–Re–Cr Alloys

An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr₂Re₃ type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.     

Kommunikationsoberfläche Membran‐ Vorbild für moderne Nanoanalytik

A central event in the life of a cellular system is the interaction between the exterior and the interior compartments. Biochemical signals arrive at the cellular surface, bind to their membrane bound receptor followed by a conformational change triggering the release of an internal chemical or electrical signal.This basic principle is followed by all our perceptive abilities like sense of smell or taste, but also by different signal transduction pathways involved in nerve conductivity, vision, sense of touch or hearing. To follow and mimic this principle of parallel registration is one of the aims of modern nanobiotechnology. If we are able to specifically biofunctionalize small arrays of a solid surface, which could be an electrode or a semiconductor, this approach will enable us to build up devices called “biochips” or “biosensors” that allow the determination of bioactive molecules with high specificity at lowest concentrations. Potential pharmacological active substrates might be screened as well as new receptors may be determined. Applications in genomics as well as proteomics are realistic. The major prerequisite for such a broad spectrum of applications is the fabrication of receptive surfaces. Biomolecules have to be surface‐adsorbed in a highly reproducible, oriented and well organised fashion, a task which in biology is taken by the cellular membranes as external or internal receptive surfaces. The physical principles like hydrogen bonds, electrostatic or hydrophobic interactions that lead to such an organized surface are well known. To synthesize molecular building blocks and to position them onto an otherwise unspecific surface is one of the challenges of nanobiotechnology combining biological knowledge and chemical skills with biophysical techniques that allow to handle or analyze even single molecules.     

The global institutionalization of nanotechnology research: A bibliometric approach to the assessment of science policy

Based on bibliometric methods, this paper describes the global institutionalization of nanotechnology research from the mid-1980s to 2006. Owing to an extremely strong dynamics, the institutionalization of nanotechnology is likely to surpass those of major disciplines in only a few years. A breakdown of the relative institutionalizations strengths by the main geographical regions, countries, research sectors, disciplines, and institutional types provides a very diverse picture over the time period because of different national science policies. The results allow a critical assessment of the different science policies based on the relative institutionalizations strengths as well as the conclusion that the institutionalization process has run out of control of individual governments who once induced the development.     

Expression of a functional tagged human thyrotropin receptor in HeLa cells using recombinant vaccinia virus

The aim of the present study was to assess the prognostic relevance of relatives' interactive behaviour towards the patient, as covered by the Münster Family Interview (MFI), to the further course of the schizophrenic illness. The MFI is a family interview (of the whole family, including the patient) designed to record the emotional family atmosphere based on the concept of expressed emotion (EE). The ratings take place directly after the interview on five scales (criticism, hostility, overinvolvement, resignation and warmth), the resignation scale being added to the 'classic' EE scales. Ninety-nine families of outpatients diagnosed with schizophrenia according to the DSM-III were examined with the MFI during a home visit. The patients were seen 1 and 2 years after the first examination. The target criteria selected for the prognostic significance of the interaction measurements were: rehospitalisation within 2 years; extent of symptoms after 1 year, and psychosocial skills after 1 year. The significance of the interaction dimensions was verified in regression models. The control variable used in the regression models was the Strauss-Carpenter scale. Regression models were produced for the total group and for a subgroup of moderately ill patients. All target criteria yielded serviceable prediction models. The most important variable for prediction was the control variable, the Strauss-Carpenter scale. However the interaction variables made additional contributions to the prognosis, especially in the subgroup of moderately ill patients. The best MFI scale for all the outcome criteria was resignation; criticism predicted only the symptomatology, and emotional overinvolvement the level of social functioning after 1 year. In conclusion, practical work with families of schizophrenic patients should emphasise the protective function of relatives towards patients more strongly.     

Relating the Morphology of Poly(p‐phenylene vinylene)/Methanofullerene Blends to Solar‐Cell Performance

The performance of bulk‐heterojunction solar cells based on a phase‐separated mixture of donor and acceptor materials is known to be critically dependent on the morphology of the active layer. Here we use a combination of techniques to resolve the morphology of spin cast films of poly(p‐phenylene vinylene)/methanofullerene blends in three dimensions on a nanometer scale and relate the results to the performance of the corresponding solar cells. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and depth profiling using dynamic time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) clearly show that for the two materials used in this study, 1‐(3‐methoxycarbonyl)propyl‐1‐phenyl‐[6,6]‐methanofullerene (PCBM) and poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene vinylene] (MDMO‐PPV), phase separation is not observed up to 50 wt.‐% PCBM. Nanoscale phase separation throughout the film sets in for concentrations of more than 67 wt.‐% PCBM, to give domains of rather pure PCBM in a homogenous matrix of 50:50 wt.‐% MDMO‐PPV/PCBM. Electrical characterization, under illumination and in the dark, of the corresponding photovoltaic devices revealed a strong increase of power conversion efficiency when the phase‐separated network develops, with a sharp increase of the photocurrent and fill factor between 50 and 67 wt.‐% PCBM. As the phase separation sets in, enhanced electron transport and a reduction of bimolecular charge recombination provide the conditions for improved performance. The results are interpreted in terms of a model that proposes a hierarchical build up of two cooperative interpenetrating networks at different length scales.