Saturation intensity and time response of InGaAs-InGaP MQW opticalmodulators

We report modulation saturation and time response measurements on InGaAs-InGaP MQW modulators. The measurements yield a saturation intensity of (3.7±0.1) kW/cm² for a 0-10 V swing and switching times between 10 and 90 ns, depending on the bias voltage and incident light intensity. The observed dependence indicates that field screening due to carrier build-up is the dominant physical mechanism determining both the speed and the saturation intensity. This conclusion is supported by results of theoretical calculations     

A neuron membrane mesh representation for visualization of electrophysiological simulations

We present a process to automatically generate three-dimensional mesh representations of the complex, arborized cell membrane surface of cortical neurons (the principal information processing cells of the brain) from nonuniform morphological measurements. Starting from manually sampled morphological points (3D points and diameters) from neurons in a brain slice preparation, we construct a polygonal mesh representation that realistically represents the continuous membrane surface, closely matching the original experimental data. A mapping between the original morphological points and the newly generated mesh enables simulations of electrophysiolgical activity to be visualized on this new membrane representation. We compare the new mesh representation with the state of the art and present a series of use cases and applications of this technique to visualize simulations of single neurons and networks of multiple neurons.     

A heuristic 0–1 integer programming method

Summary In this paper, we present a novel relaxation method for the integer programming problem:Ax=b,A {–1,0,+1}^m×N,x {0,1}^N, N>m. The report includes experimental results of problems with up tom=100 equations andN=400 variables.     

Polycyclic Aromatic Hydrocarbons Activate the Aryl Hydrocarbon Receptor and the Constitutive Androstane Receptor to Regulate Xenobiotic Metabolism in Human Liver Cells

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants produced by incomplete combustion of organic matter. They induce their own metabolism by upregulating xenobiotic-metabolizing enzymes such as cytochrome P450 monooxygenase 1A1 (CYP1A1) by activating the aryl hydrocarbon receptor (AHR). However, previous studies showed that individual PAHs may also interact with the constitutive androstane receptor (CAR). Here, we studied ten PAHs, different in carcinogenicity classification, for their potential to activate AHR- and CAR-dependent luciferase reporter genes in human liver cells. The majority of investigated PAHs activated AHR, while non-carcinogenic PAHs tended to activate CAR. We further characterized gene expression, protein abundancies and activities of the AHR targets CYP1A1 and 1A2, and the CAR target CYP2B6 in human HepaRG hepatoma cells. Enzyme induction patterns strongly resembled the profiles obtained at the receptor level, with AHR-activating PAHs inducing CYP1A1/1A2 and CAR-activating PAHs inducing CYP2B6. In summary, this study provides evidence that beside well-known activation of AHR, some PAHs also activate CAR, followed by subsequent expression of respective target genes. Furthermore, we found that an increased PAH ring number is associated with AHR activation as well as the induction of DNA double-strand breaks, whereas smaller PAHs activated CAR but showed no DNA-damaging potential.     

Energy Metabolites as Biomarkers in Ischemic and Dilated Cardiomyopathy

With more than 25 million people affected, heart failure (HF) is a global threat. As energy production pathways are known to play a pivotal role in HF, we sought here to identify key metabolic changes in ischemic- and non-ischemic HF by using a multi-OMICS approach. Serum metabolites and mRNAseq and epigenetic DNA methylation profiles were analyzed from blood and left ventricular heart biopsy specimens of the same individuals. In total we collected serum from n = 82 patients with Dilated Cardiomyopathy (DCM) and n = 51 controls in the screening stage. We identified several metabolites involved in glycolysis and citric acid cycle to be elevated up to 5.7-fold in DCM (p = 1.7 × 10⁻⁶). Interestingly, cardiac mRNA and epigenetic changes of genes encoding rate-limiting enzymes of these pathways could also be found and validated in our second stage of metabolite assessment in n = 52 DCM, n = 39 ischemic HF and n = 57 controls. In conclusion, we identified a new set of metabolomic biomarkers for HF. We were able to identify underlying biological cascades that potentially represent suitable intervention targets.     

On Iron Metabolism and Its Regulation

Iron is a critical metal for several vital biological processes. Most of the body’s iron is bound to hemoglobin in erythrocytes. Iron from senescent red blood cells is recycled by macrophages in the spleen, liver and bone marrow. Dietary iron is taken up by the divalent metal transporter 1 (DMT1) in enterocytes and transported to portal blood via ferroportin (FPN), where it is bound to transferrin and taken up by hepatocytes, macrophages and bone marrow cells via transferrin receptor 1 (TfR1). While most of the physiologically active iron is bound hemoglobin, the major storage of most iron occurs in the liver in a ferritin-bound fashion. In response to an increased iron load, hepatocytes secrete the peptide hormone hepcidin, which binds to and induces internalization and degradation of the iron transporter FPN, thus controlling the amount of iron released from the cells into the blood. This review summarizes the key mechanisms and players involved in cellular and systemic iron regulation.     

Efficient material design for diesel particulate filters

This paper will give an overview about the filter development for diesel particulate emission control in automotive applications. The material development for passenger car diesel particulate filters led to new materials like silicon carbide while for heavy duty applications still Cordierite plays a major role. But in the future other materials might also be used for passenger cars. This paper will show the basic difference between both applications and describe the material design in terms of filter properties (base material, back pressure aspects, filtration efficiency, coating impact). Current application on vehicles with catalysed soot filters (CSF) with and without oxidation catalyst will be presented. Furthermore an outlook will be given on materials for catalysed soot filters for the future.     

LIGA micro-openings for coherence characterization of X-rays

Infinitely thin opaque screens serving for diaphragms as defined in the visible-light optics are not feasible for operation with X-ray beams due to their high penetrability. Micro-openings of predicted sidewall shape in a gold layer up to 140 μm thick which would provide low transparency, are proposed. The proposed micro-openings were made using the LIGA technique and tested successfully at photon energies of up to 25 keV. The micro-openings can be used as targets for coherence X-ray pattern or, if long interference tails are avoided by means of the advanced sidewall shape, as X-ray beam collimators.     

High-pressure fluidized bed coating utilizing supercritical carbon dioxide

Various particles with sizes between 100 and 200 μm were encapsulated with waxes commonly used in technical coating applications. For this, a homogeneous mixture of molten paraffin and supercritical carbon dioxide was prepared in an autoclave and injected into the high-pressure fluidized bed through a nozzle from the bottom. Due to the different conditions in the mixing autoclave and the fluidized bed, the paraffin precipitated in the vicinity of the nozzle and adhered to the solid particles. A complete, thin, uniform, and solvent-free coating was produced. The use of two paraffins with different alkane compositions resulted in dissimilar spreads on glass beads due to their different glass transition temperatures. A smaller pressure drop across the nozzle led to more uniform and even coatings. Glass beads, ceramic spheres, potassium chloride, and lactose showed similar coating results, whereas different morphologies were observed with a plastic material, characterized by a rougher surface and a lower surface energy. The high quality of the coating was confirmed by standard dissolution tests with coated potassium chloride crystals and lactose agglomerates.     

An AC 1-complete model checking problem for intuitionistic logic

We show that the model checking problem for intuitionistic propositional logic with one variable is complete for logspace-uniform AC ¹. For superintuitionistic logics with one variable, we obtain NC ¹-completeness for the model checking problem.