Insulin resistance and impaired insulin secretion due to phosphofructo-1-kinase-deficiency in humans

Recent epidemiologic evidence suggests that patients with chronic pancreatitis (CP) have an increased risk of developing pancreatic carcinoma (PCA). In spite of numerous similarities in both diseases, mechanisms for progression from CP to PCA are poorly understood. We hypothesized that enhanced angiogenesis might play a pivotal role in the etiology and histopathology of both CP and PCA, and thus form a possible link between precancer and carcinoma. In surgical specimens of 18 patients with CP, 10 with PCA, and 18 controls, absolute numbers of blood vessels and relative blood vessel density were assessed after immunostaining of endothelial cells for von Willebrand factor and PECAM-1 (platelet/ endothelial cell adhesion molecule-1). Furthermore, the expression of cell adhesion molecules ICAM-1 (intercellular adhesion molecule-1) and VCAM-1 (vascular cell adhesion molecule-1) and of VEGF (vascular endothelial growth factor) was investigated in all specimens. Both CP and PCA exhibited areas of high vascular density ("hot spots"). The mean number of blood vessels in these areas in PCA was 132.2+/-16.8 per mm2, and in CP, 99.2+/-7.4 per mm2. The mean vessel count in controls was 25.1+/-5.1. Relative vessel density was increased in both PCA (41.3+/-3.5%) and CP (30.6+/-2.6%) versus controls (8.0+/-0.8%). Both absolute vessel count and relative vessel density were significantly higher (p<0.05) in PCA than in CP. Enhanced expression of ICAM-1 in CP and PCA was seen in ductal cells in CP and cancer cells. In controls, ICAM-1 and VCAM-1 were expressed only at low levels in endothelial cells. VCAM-1 was strongly expressed in acinar cells as well as in ductal cells. In CP and PCA, VEGF was strongly expressed in ductal cells in CP as well as in cancer cells. We show for the first time that angiogenic activity is increased in both CP and PCA. Based on this study, we suggest that antiangiogenesis might be a novel target for prevention or therapy in chronic pancreatic diseases.     

Directional reflectance properties determined by analysis of airborne multispectral scanner data and atmospheric correction

Directional reflectance properties of natural surfaces are very important in the interpretation of remotely sensed data. The analysis of multispectral scanner data shows a distinct dependence on scan angle, wavelength (0.4–1.1 μm), and classes (e.g., bare soil, vegetation). This relationship can be described by polynomials determined by regression methods. Atmospheric effects are computed with a simple model by parametrization of the multiple scattered skylight. The model permits a quick and sufficient estimation of the airlight, depending on the data collection conditions. Comparisons of the scanner data with the corresponding model yield the following results: The differences between airborne and ground measurements are due to atmospheric effects. The directional variation in brightness is mainly caused by the object itself with the exception of short wavelengths and/or a very low albedo. The hue shift of vegetation is essentially produced by the object and modified by the atmosphere. Taking into account the directional reflectance properties in a direction-dependent classification procedure results in an improvement of up to 20% in comparison with algorithms used so far. Quantitative relationships between ground measurements and radiation measurements by airborne sensors including atmospheric effects can be determined with the proposed methods.     

Das Oxidationsverhalten von Heizleiter-Legierungen

The oxidation behaviour of resistance heater alloys The prime condition for the use of metals as resistance heaters is their capability of forming compact and well adhering layers of scale of low permeability. In this context the composition of the alloy (in particular ferritic steels and representatives from the system NiCr) Play an important role in so far as oxidation has frequently a selective character, so that certain constituents may be depleted. Adhesion is also a function of the temperature regime (constant or cycling temperature during scale formation) be-cause these conditions may give rise to internal stresses in the covering layer. A tool for measuring stresses in the scale layer and thus adhesion is in particular the vibration method. In non-oxidising atmospheres increased chromium contents are generally useful; on the one hand they improve resistance to carburation and On the other hand they have a favourable influence on the resistance of nickel alloys in sulfidising atmospheres.     

Organic Thin‐Film Photovoltaic Cells Based on Oligothiophenes with Reduced Bandgap

The best polymeric solar cells reported so far are based on a so‐called bulk heterojunction of a polythiophene as donor and a soluble fullerene derivative as acceptor. However, these cells still suffer from an unsatisfying photovoltage, typically below 0.7 V. Here, we show that we can achieve higher photovoltages using a new terthiophene end‐capped with electron withdrawing dicyanovinyl groups (DCV3T) that increase both the ionization energy and even more strongly the electron affinity of the compound. The new material is tested in cells using a photoactive heterojunction to separate the excitons generated in the oligomer and a p‐doped wide‐gap transport layer. The solar cells show an open circuit voltage of up to 1.04 V and a broad spectral sensitivity band ranging from 420 nm to 650 nm. Solar cells based on such oligothiophenes are promising candidates for stacked organic solar cells tailored to the sun‐spectrum. Moreover, we present first examples of a new concept for organic solar cells: By blending DCV3T with fullerene C₆₀, an enhanced generation of triplet excitons on the oligomer can be achieved via a back and forth transfer of excitons (ping‐pong‐effect).     

Controlled p-doping of pigment layers by cosublimation: Basic mechanisms and implications for their use in organic photovoltaic cells

We present a systematic study on doping of vanadyl- and zinc-pathalocyanine by a fully fluorinated form of tetracyano-quinodimethane as an example of controlled doping of thin organic films by cosublimation of matrix and dopant. The films are characterized in situ by temperature dependent Seebeck and conductivity measurements. We observe a drastic increase of conductivity and a corresponding shift of the Fermi level towards the valence states with increasing dopant concentration. We thus conclude that doping has the potential of both reducing the series resistance and increasing the photovoltage of organic solar cells. As a first step to exploit this potential, we present two different ways of preparing diodes with rectification ratios in excess of 10⁴ using doped phthalocyanines. By adding an undoped interlayer between the contact and the doped layer, we have produced diodes which work already in the strict absence of oxygen and are stable in air. To increase the efficiency of charge carrier generation in photovoltaic cells, we need to use photoactive donor–acceptor-heterojunctions. We present here first examples of pn- and pin-type heterojunctions combining p-doped and nominally undoped layers.     

Synthesis of macroporous ZrO2–Al2O3 mixed oxides with mesoporous walls, using polystyrene spheres as template

Macroporous ZrO₂–Al₂O₃ mixed oxides with mesoporous walls were synthesized. The three-dimensional interconnected macroporous structures, of inorganic zirconia–alumina mixed oxides containing different alumina compositions (25, 50, 100 wt%), were prepared by sol–gel method from inorganic precursors and using polystyrene microspheres with diameters of 685 and 1520 nm as templates. The final porous arrays with controllable pore size in the submicrometer range could be obtained by calcination of the organic template. The structural characteristics are discussed. The physicochemical characterization of the samples was carried out by N₂ physisorption (S_BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The shrinkage of pore diameter was approximately 35%, and the wall thickness of inorganic framework varied between 135 and 154 nm. The specific surface areas, of the samples, were between 123 and 287 m²/g, obtaining the largest surface area with the highest alumina contents and the smallest templates.