Mathematische Formulierung der Erzreduktion für ein Hochofenmodell

Ableitung eines reaktionskinetischen Ansatzes zur Beschreibung der Erzreduktion im Hochofen nach einer Reaktion erster Ordnung. Erörterung der möglichen Abweichungen von einer Reaktion erster Ordnung. Übertragung der in Laboratoriumsversuchen an niedrigen Schüttungen ermittelten Reaktionsdaten auf Hochofenverhältnisse. Aussagen über die Verweilzeitverteilung der Gasmoleküle innerhalb der Schüttung. Beschreibung des Vorgehens bei der Bestimmung der bezogenen Reduktionsgeschwindigkeiten und der effektiven Gleichgewichtszusammensetzung des Reaktionsgases. Angaben zur Erfassung des Einflusses von Wasserstoffgehalten auf die Reduktionsgeschwindigkeit. Aussagen über den Ablauf der Wassergasreaktion im Hochofen.     

Prostaglandin E synthase 2 (PTGES2) Arg298His polymorphism and parameters of the metabolic syndrome

The prostaglandin E synthase 2 (PTGES2) gene maps to a locus linked to obesity and is involved in the synthesis of the antilipolytic compound prostaglandin E(2). In a recent study, we found an association of the minor PTGES2 Arg298His allele and lower risk of type 2 diabetes mellitus in the European Investigation into Cancer and Nutrition (EPIC) and Cooperative Health Research in the Augsburg Region (KORA) cohorts. Here, we employed our Metabolic Intervention Cohort Kiel (MICK) to assess the influence of the PTGES2 Arg298His polymorphism on a wider scale of parameters of the metabolic syndrome and postprandial metabolism. In comparison to subjects homozygous for the Arg allele, carriers of the His-allele showed significantly lower fasting insulin (geometric mean +/- SEM: 11.8 muU/mL, 11.41-12.25 versus 13.0, 12.71-13.33; p = 0.023), lower postprandial insulin levels after an oral glucose tolerance test (area under the curve 77.2, 74.07-80.52 versus 81.2, 78.8-83.63; p = 0.023) and lower homeostasis model assessment (HOMA)-insulin-resistance (3.030, 2.909-3.157 versus 3.346, 3.257-3.438; p = 0.041) and HOMA-beta-cell-function (107.2, 104.04-110.52 versus 117.2, 114.65-119.71; p = 0.019). Adjustment for body mass index (BMI) resulted in a loss of these significant differences. BMI tended to show lower values in His-allele carriers, (p = 0.067). In conclusion, risk-reducing effects of the minor His allele of the PTGES2 Arg298His polymorphism could be mediated partly by lowered BMI.     

Synthesis of active carbon-based catalysts by chemical vapor infiltration for nitrogen oxide conversion

Direct reduction of nitrogen oxides is still a challenge. Strong efforts have been made in developing noble and transition metal catalysts on microporous support materials such as active carbons or zeolites. However, the required activation energy and low conversion rates still limit its breakthrough. Furthermore, infiltration of such microporous matrix materials is commonly performed by wet chemistry routes. Deep infiltration and homogeneous precursor distribution are often challenging due to precursor viscosity or electrostatic shielding and may be inhibited by pore clogging. Gas phase infiltration, as an alternative, can resolve viscosity issues and may contribute to homogeneous infiltration of precursors. In the present work new catalysts based on active carbon substrates were synthesized via chemical vapor infiltration. Iron oxide nano clusters were deposited in the microporous matrix material. Detailed investigation of produced catalysts included nitrogen oxide adsorption, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Catalytic activity was studied in a recycle flow reactor by time-resolved mass spectrometry at a temperature of 423 K. The infiltrated active carbons showed very homogeneous deposition of iron oxide nano clusters in the range of below 12 to 19 nm, depending on the amount of infiltrated precursor. The specific surface area was not excessively reduced, nor was the pore size distribution changed compared to the original substrate. Catalytic nitrogen oxides conversion was detected at temperatures as low as 423 K.     

Broadband Omnidirectional Diversion of Light in Hybrid Plasmonic‐Photonic Heterocrystals

Broadband, omnidirectional, and polarization‐independent diversion has been achieved of more than 90% of the light flow intensity off its incidence direction using hybrid metal–dielectric plasmonic‐photonic heterocrystals. These architectures were prepared by depositing metal film on the interface between two photonic crystals of different parameters. The magnitude of light losses was extracted from angle‐resolved measurements of transmission and reflectance spectra. Comparing these data for different stages of constructing the complex architecture, the diffraction in colloidal crystals, the excitation and radiative decay of short‐living surface plasmon polaritons in a corrugated metal film and the eigenmode mismatch at the interface between two different photonic crystals were identified as corroborating physical mechanisms behind the light diversion.     

A study of airborne wear particles generated from organic railway brake pads and brake discs

Brake pads on wheel-mounted disc brakes are often used in rail transport due to their good thermal properties and robustness. During braking, both the disc and the pads are worn. This wear process generates particles that may become airborne and thus affect human health. The long term purpose of ‘Airborne particles in Rail transport’ project is to gain knowledge on the wear mechanisms in order to find means of controlling the number and size distribution of airborne particles. In this regard, a series of full-scale field tests and laboratory tests with a pin-on-disc machine have been conducted. The morphology and the matter of particles, along with their size distribution and concentration, have been studied. The validity of results from the pin-on-disc simulation has been verified by the field test results. Results show an ultra-fine peak for particles with a diameter size around 100 nm in diameter, a dominant fine peak for particles with a size of around 350 nm in diameter, and a coarse peak with a size of 3–7 μm in diameter. Materials such as iron, copper, aluminum, chromium, cobalt, antimony, and zinc have been detected in the nano-sized particles.     

City energy management through underground storage

This paper traces the historical development of the energy infrastructure of cities. As a result of 150 years of this infrastructure mainly comprises electricity, gas, and, sometimes, district heating. This paper describes basic characteristics of underground storage systems applicable within city limits: gas storage, compressed air energy storage, and thermal storage. Finally, the paper describes a central storage facility for all energy forms that has the potential to provide much of the flexibility required for optimal city energy management.     

Classification of jointed rock with emphasis on grouting

This article includes the mathematical foundations of a proposed geometrical model describing the rock, and shows how the geometrical properties of the rock mass can be evaluated. The base for evaluating the parameters describing the rock mass can be a continuous recording of the flow and pressure for a grout hole during a grouting session. Recorded data are then fitted to a mathematical function that describes the flow in the geometrical model. A rough estimation of the geometrical properties can also be done from the volume of injected grout, combined with ordinary water pressure tests. The evaluated geometry can be used to classify the rock.