Diamantartige Kohlenstoffschichten steigern die Effizienz

Diamond‐like carbon thin films enhance efficiency — laser arc deposition of ta‐C Rising prices for fossil fuels as well as the increasing effects of the climate change due to the emission of greenhouse gases reveal the necessity of saving energy. Low friction coatings have an enormous potential in saving energy. Carbon based coatings — named as DLC coatings — are especially well suited for low friction coatings. In particular hydrogen‐free tetrahedral amorphous carbon (ta‐C) coatings are of great interest due to their extraordinary low wear properties. In addition they show excellent low friction properties and especially in combination with specific lubricants the so‐called super low friction effect. For the deposition of ta‐C coatings PVD methods have to be applied instead of CVD methods as it is the case for conventional DLC coatings. We have developed a deposition method which is based on a pulsed arc steered by a laser (Laser‐Arc). This allows us to use large cathodes resulting in a high long‐term stability. Furthermore, the carbon plasma source can be combined with a filtering unit removing almost all droplets and particles, which usually are characteristic for an arc process. The resulting Laser‐Arc source allows for the deposition of smooth and virtually defect‐free ta‐C coatings with a competitive deposition rate.     

On the Cooling Rate-Microstructure Relationship in Molten Metal Gas Atomization

Metallurgical and Materials Transactions A - Gas atomization is the most used powder production technique since it provides good control on particles shape, surface oxidation and dimension. It is a...     

Anti-Inflammatory Characteristics of Local Anesthetics: Inhibition of TNF-α Secretion of Lipopolysaccharide-Stimulated Leucocytes in Human Blood Samples

Background. Local anesthetics (LAs) have potent anti-inflammatory properties. Inflammatory down-regulation is crucial in diseases with overactive immune reactions, such as acute respiratory distress syndrome (ARDS) and chronic inflammation. We investigated the influence of four LAs, procaine, lidocaine, mepivacaine, and bupivacaine, on the reduction of tumor necrosis factor-alpha (TNF-α) secretion in lipopolysaccharide (LPS)-activated human leucocytes. Methods. Blood samples of 28 individuals were stimulated with LPS. The reduction of TNF-α production by each of the four LAs added (0.5 mg/mL) was measured and correlated with biometric variables. A response was defined as reduction to <85% of initial levels. Results. All four LAs down-regulated the TNF-α secretion in 44–61%: Bupivacaine (44.4%), lidocaine (61.5%), mepivacaine (44.4%), and procaine (50% of the individuals, “responders”). The TNF-α secretion was reduced to 67.4, 68.0, 63.6, and 67.1% of the initial values in responders. The effects in both patients and healthy persons were the same. Interindividual responses to LAs were not correlated with the duration or type of complaints, basal TNF-α serum level, sex, BMI, or age of responders. Conclusions. Four clinically relevant LAs (amid-LA and ester-LA) attenuate the inflammatory response provoked by LPS. They are potential candidates for drug repositioning in treating overactive immune reactions and chronic inflammation.     

Male pheromone of swift moth,Hepialus hecta L. (Lepidoptera: Hepialidae)

(R)-6-Ethyl-2-methyl-2,3-dihydro-4H-pyran-4-one, (1R,3S,5R)-3-ethyl-1,8-dimethyl-2,9-dioxabicyclo[3.3. 1]non-7-ene, and (1R,3S,5R)-3-ethyl-1,8-dimethyl-2,9-dioxabicyclo[3.3.1]non-7-en-6-one represent the main components in the male pheromone of the swift moth,Hepialus hecta. The amounts of the three components were 40, 5, and 5 g per male, respectively. Structure elucidation of the compounds was based on spectroscopic data as compared to synthetic reference samples. The absolute configurations were determined by gas chromatography on chiral stationary phases; optically active samples served as reference compounds. Electrophysiological and behavioral experiments with natural material and synthetic samples clearly showed the three heterocyclic compounds to act as pheromones. (E, E)--Farnesene represents the main component of the scent secretion of maleHepialus humuli.     

A compact photomicroreactor design for kinetic studies of gas‐liquid photocatalytic transformations

A compact photomicroreactor assembly consisting of a capillary microreactor and small‐scale light emitting diodes was developed for the study of reaction kinetics in the gas‐liquid photocatalytic oxidation of thiophenol to phenyl disulfide within Taylor flow. The importance of photons was convincingly shown by a suction phenomenon due to the fast consumption of oxygen. Mass transfer limitations were evaluated and an operational zone without mass transfer effects was chosen to study reaction kinetics. Effects of photocatalyst loading and light sources on the reaction performance were investigated. Reaction kinetic analysis was performed to obtain reaction orders with respect to both thiophenol and oxygen based on heterogeneous and homogeneous experimental results, respectively. The Hatta number further indicated elimination of mass transfer limitations. Reaction rate constants at different photocatalyst loadings and different photon flux were calculated. Furthermore, the advantages of this photomicroreactor assembly for studying gas‐liquid photocatalytic reaction kinetics were demonstrated as compared with batch reactors. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2215–2227, 2015     

Redox processes in pressurised smoked salmon studied by resonance Raman spectroscopy

Non-thermal food preservation technology is based on the application of high pressures up to 600 MPa. Here we report a resonance Raman (RR) spectroscopic analysis of smoked salmon meat after high pressure processing. High quality spectra, which can be obtained even from packed salmon without spectral interference of the packing foil, allow determining pressure-dependent irreversible changes of the main RR-active components of salmon meat, astaxanthin and myoglobin/haemoglobin. High pressure-treatment causes a decrease of the relative RR intensities of astaxanthin as probed with 514 nm excitation which is in line with a slight attenuation of the originally intense red colour of the salmon meat. 413-nm excited RR spectra indicate a heterogeneous broadening of astaxanthin bands accompanied by the formation of deoxy-myoglobin or deoxy-haemoglobin. The results suggest that pressure-treatment facilitates the oxidative degradation of astaxanthin coupled to the reduction of metmyoglobin (methaemoglobin).     

On boundary conditions for homogenization of volume elements undergoing localization

This paper presents an adaption of periodic boundary conditions (BC), which is termed tessellation BC. While periodic BC restrict strain localization zones to obey the periodicity of the microstructure, the proposed tessellation BC adjust the periodicity frame to meet the localization zone. Thereby, arbitrary developing localization zones are permitted. Still the formulation is intrinsically unsusceptible against spurious localization. Additionally, a modification of the Hough transformation is derived, which constitutes an unbiased criterion for the detection of the localization zone. The behavior of the derived formulation is demonstrated by various examples and compared with other BC. It is thereby shown that tessellation BC lead to a reasonable dependence of the effective stress on the localization direction. Furthermore, good convergence of stiffness values with increasing size of the representative volume element is shown as well as beneficial characteristics in use with strain softening material.     

Aerosol lidar intercomparison in the framework of the EARLINET project. 3. Raman lidar algorithm for aerosol extinction, backscatter, and lidar ratio

An intercomparison of the algorithms used to retrieve aerosol extinction and backscatter starting from Raman lidar signals has been performed by 11 groups of lidar scientists involved in the European Aerosol Research Lidar Network (EARLINET). This intercomparison is part of an extended quality assurance program performed on aerosol lidars in the EARLINET. Lidar instruments and aerosol backscatter algorithms were tested separately. The Raman lidar algorithms were tested by use of synthetic lidar data, simulated at 355, 532, 386, and 607 nm, with realistic experimental and atmospheric conditions taken into account. The intercomparison demonstrates that the data-handling procedures used by all the lidar groups provide satisfactory results. Extinction profiles show mean deviations from the correct solution within 10% in the planetary boundary layer (PBL), and backscatter profiles, retrieved by use of algorithms based on the combined Raman elastic-backscatter lidar technique, show mean deviations from solutions within 20% up to 2 km. The intercomparison was also carried out for the lidar ratio and produced profiles that show a mean deviation from the solution within 20% in the PBL. The mean value of this parameter was also calculated within a lofted aerosol layer at higher altitudes that is representative of typical layers related to special events such as Saharan dust outbreaks, forest fires, and volcanic eruptions. Here deviations were within 15%.     

Relationship between structure and electroluminescence of oligo(p-phenylenevinylene)s

The preparation of LEDs with poly( p-phenylenevinylene) (PPV) as emitting material is well established. However, due to the presence of a distribution of conjugated chain lengths in the polymer, systematic investigations of the electroluminescence with polymeric materials are difficult, as far as the optical emission is concerned. We are studying the relationship between structural variation of substituted oligo(p-phenylenevinylene)s and their electroluminescent behaviour using a series of distyrylbenzenes with a variety of substituents in order to investigate their influence on the electroluminescence (EL). Furthermore, we synthesized a homologous series of monodisperse oligo(2,5-dipropoxy-1,4-phenylenevinylene)s with up to 11 repeating units. This series covers the spectrum from monomer to polymer. The influence on the EL can be investigated by preparing single layer LEDs using vapor deposition or spincoating of the oligomers in a polystyrene (PS) matrix. The comparison of photoluminescence (PL)- and EL-spectra shows that the photophysical properties of the oligomers are strongly altered by aggregation phenomena.