Measurement of temporal and spatial resolved rotational temperature in ignition sparks at atmospheric pressure

In this work, the temporal and spatial rotational temperature, as an indicator of spark temperature in the gas, of an ignition spark at ambient pressure is determined. With optical emission spectroscopy, the rotational bands of the nitrogen C3Πu → B3Πg transition at a wavelength of 337 nm are for determination. In addition, the electrical values of the current and the voltage are measured with a digital storage oscilloscope. All measurements are performed with a common nickel spark plug and a commercial 90 mJ ignition coil. The dwell time of the coil is varied in four steps from 100 to 25% and the influence on the rotational temperature is measured. The results are split into the three spark phases: breakdown, arc discharge, and glow discharge. The results show a cold breakdown, which is independent from the dwell time. On average, arc discharge is the hottest discharge phase, while the glow discharge has a medium rotational temperature

Spatial and time resolved determination of the vibrational temperature in ignition sparks by variation of the dwell time

The ignition process initiates the combustion in spark-ignition engines. Therefore, understanding the ignition process is an important aspect in developing more efficient combustion engines. In this thesis, the vibrational temperature of an ignition spark in air under atmospheric pressure and room temperature is observed in spatial and temporal resolution. The temperature is determined by comparing simulated spectra with the measured spectra of the second positive system of N2 between 360 and 381 nm. Changing the dwell time had no significant effect on the vibrational temperature of the three spark phases. In the breakdown the vibrational temperature is about 3300 K. The vibrational temperature of the following arc discharge is in the range of 3750 K to 4350 K. The glow discharge is divided into the negative glow and the positive column. Both show similar vibration temperatures in the range of 3500 K to 3900 K

Die Rolle von Cannabinoid 2 (CB2)-Rezeptoren bei der akuten Pankreatitis

BACKGROUND: The endocannabinoid system (ECS) consists of the cannabinoid receptors 1 (CB1) and 2 (CB2), endogenous ligands (lipids) and endocannabinoid-degrading mechanisms. To date the best characterized endogenous cannabinoids are anandamide (AEA) and 2-arachidonoyl-glycerol (2-AG). Both act as agonists on CB1 and CB2-receptors. Activation of CB2-receptors results in anti-inflammatory and analgesic effects, two characteristics which seem beneficial for treatment of acute pancreatitis. Furthermore, the activation of the MAP-kinases p38 and JNK by CB2-receptors has been described in other tissues. These two intra-cellular signaling-cascades have been shown to be involved in the early acinar events which lead to acute pancreatitis. Our aim was to examine the role of CB2-receptors in the pathophysiology of acute pancreatitis and the potential involvement of p38 and JNK in mediating the effects of their activation. Also, we looked at the therapeutic potential of administration of synthetic CB2-agonists. METHODS: Pancreatitis was induced by six hourly intra-peritoneal injections of cerulein (50µg/kg bw) in wild-type C57/bl and MK2 -/- mice. JWH133, a synthetic and specific CB2-agonist, or AM 630, a specific CB2 receptor antagonist, was administered 30 min prior to the first cerulein injection. Expression and distribution of CB2-receptors in pancreatic tissue was examined by RT-quantitative PCR, western blotting and immunohistochemistry. Severity of pancreatitis was determined by measuring serum amylase, IL-6 levels, trypsinogen activation, MPO activity and histological examinations. Pancreatic lysates were investigated by western blotting using phospho specific antibodies against p38 and JNK. RESULTS: Cannabinoid 2-receptors are expressed on acinous cells and other cell types of mouse pancreas. In state of acute pancreatitis an up-regulation and also an increased activation through endogenous ligands can be observed which leads to an attenuation of the pathology. This effect can be therapeutically exploited by administration of a synthetic CB2-agonist. Correlating to the protective effects, an increased intra-acinous activation of p38 and an inhibition of JNK can be observed. The known protective effects of p38 are mediated through activation of the kinase MK2 which again activates HSP27. Experiments in MK2 -/- mice show that at least the reduction of IL-6 levels and MPO activity are dependent on this pathway. Since pro-inflammatory cytokines like IL-6 are known to activate JNK in acinous cells, the observed inhibition of JNK by CB2-receptor activation might indirectly be mediated by MK2-dependend reduction of these cytokines

Deformation and fracture mechanisms in nanocomposite and nanolaminate thin films revealed through combinatorial design and nanomechanical testing

We’ve integrated an atomic layer deposition (ALD), a physical vapor deposition (PVD) and a nanoparticle inert gas condensation (NP) deposition system into a single vacuum chamber. This combined system allows for PVD sputtering of micrometer thick films and incorporation of size filtered nanoparticles and/or controlled deposition of mono-layer highly conformal film coatings within a multilayer structure. In this way, unique model thin film microstructures can be architectured. We designed three thin films to understand the basic mechanism of plasticity and fracture in thin films: a) Al2O3 oxide films were deposited on combinatorial libraries of the ternary noble metal alloys with full compositional range to understand interfacial adhesion between oxide and noble metal alloys b) monosized tungsten nanoparticles were deposited at the interface of Cu/Ni multilayers to understand how thin film hardness and thermal stability can be engineered, c) ultrathin monolayers of Al2O3 layers were sandwiched between sputtered Al layers and micropillar compression was used to understand dislocation transmission and fracture across ultrathin ceramic layers. Please click Additional Files below to see the full abstract

Die Rolle von Cannabinoid 2 (CB2)-Rezeptoren bei der akuten Pankreatitis

BACKGROUND: The endocannabinoid system (ECS) consists of the cannabinoid receptors 1 (CB1) and 2 (CB2), endogenous ligands (lipids) and endocannabinoid-degrading mechanisms. To date the best characterized endogenous cannabinoids are anandamide (AEA) and 2-arachidonoyl-glycerol (2-AG). Both act as agonists on CB1 and CB2-receptors. Activation of CB2-receptors results in anti-inflammatory and analgesic effects, two characteristics which seem beneficial for treatment of acute pancreatitis. Furthermore, the activation of the MAP-kinases p38 and JNK by CB2-receptors has been described in other tissues. These two intra-cellular signaling-cascades have been shown to be involved in the early acinar events which lead to acute pancreatitis. Our aim was to examine the role of CB2-receptors in the pathophysiology of acute pancreatitis and the potential involvement of p38 and JNK in mediating the effects of their activation. Also, we looked at the therapeutic potential of administration of synthetic CB2-agonists. METHODS: Pancreatitis was induced by six hourly intra-peritoneal injections of cerulein (50µg/kg bw) in wild-type C57/bl and MK2 -/- mice. JWH133, a synthetic and specific CB2-agonist, or AM 630, a specific CB2 receptor antagonist, was administered 30 min prior to the first cerulein injection. Expression and distribution of CB2-receptors in pancreatic tissue was examined by RT-quantitative PCR, western blotting and immunohistochemistry. Severity of pancreatitis was determined by measuring serum amylase, IL-6 levels, trypsinogen activation, MPO activity and histological examinations. Pancreatic lysates were investigated by western blotting using phospho specific antibodies against p38 and JNK. RESULTS: Cannabinoid 2-receptors are expressed on acinous cells and other cell types of mouse pancreas. In state of acute pancreatitis an up-regulation and also an increased activation through endogenous ligands can be observed which leads to an attenuation of the pathology. This effect can be therapeutically exploited by administration of a synthetic CB2-agonist. Correlating to the protective effects, an increased intra-acinous activation of p38 and an inhibition of JNK can be observed. The known protective effects of p38 are mediated through activation of the kinase MK2 which again activates HSP27. Experiments in MK2 -/- mice show that at least the reduction of IL-6 levels and MPO activity are dependent on this pathway. Since pro-inflammatory cytokines like IL-6 are known to activate JNK in acinous cells, the observed inhibition of JNK by CB2-receptor activation might indirectly be mediated by MK2-dependend reduction of these cytokines

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Diffusion-based deformation in elevated temperature micropillar compression of Mg-Nb multilayers

multilayer, elevated-temperature, micropillar compressio

Correlative in situ total and elastic strain mapping on micromechanical test pieces by DIC and HR-EBSD

The measurement of elastic strains and stress in micromechanical testpieces upon loading has previously been performed by in-situ X-ray synchrotron diffraction and high resolution electron backscatter diffraction (HR-EBSD). Similarly, the measurement of total, elastic and plastic, strains by the technique of digital image correlation (DIC) strain mapping, has recently been performed on micropillars using an applied surface speckle pattern. Please click Additional Files below to see the full abstract

Influence of the Electrical Parameters of the Ignition System on the Phases of Spark Ignition

Untersucht wurde der Einfluss der Kapazität auf das Spektrum der Funkenzündung. Im Mittelpunkt der Untersuchung standen die Spektren von N2 bei 337nm, N2+ bei 391nm, N bei 500nm und O bei 777nm. Dabei wurde ein Zündfunken mit verschiedenen, unmittelbar vor der Zündkerze, montierten Kapazitäten zeitlich abgetastet. Dabei konnte vor allem eine starke Erhöhung der kapazitiv gespeisten Bogenentladung beobachtet werden. Diese resultiert in eine Erhöhung der Nickelemission im Gas. Die 2. pos. Gruppe von Stickstoff bei 337nm weist in dem kapazitiven Bogen eine höhere Intensität auf sobald die Kapazität wächst. Zusätzlich zeigt das Spektrum der 1. neg. Gruppe von Stickstoff bei 391nm erst zum Einsetzen der Glimmentladung eine hohe Leuchterscheinung welche sich auf die Kathode beschränkt. Des Weiteren konnte atomarer Stickstoff nur im Bereich des Durchbruchs und der kapazitiven Bogenentladung gefunden werden. Bei atomarem Sauerstoff konnte eine Reduktion der Emission beobachtet werden

Scale-invariance of receptive field properties in primary visual cortex

<p>Abstract</p> <p>Background</p> <p>Our visual system enables us to recognize visual objects across a wide range of spatial scales. The neural mechanisms underlying these abilities are still poorly understood. Size- or scale-independent representation of visual objects might be supported by processing in primary visual cortex (V1). Neurons in V1 are selective for spatial frequency and thus represent visual information in specific spatial wavebands. We tested whether different receptive field properties of neurons in V1 scale with preferred spatial wavelength. Specifically, we investigated the size of the area that enhances responses, i.e., the grating summation field, the size of the inhibitory surround, and the distance dependence of signal coupling, i.e., the linking field.</p> <p>Results</p> <p>We found that the sizes of both grating summation field and inhibitory surround increase with preferred spatial wavelength. For the summation field this increase, however, is not strictly linear. No evidence was found that size of the linking field depends on preferred spatial wavelength.</p> <p>Conclusion</p> <p>Our data show that some receptive field properties are related to preferred spatial wavelength. This speaks in favor of the hypothesis that processing in V1 supports scale-invariant aspects of visual performance. However, not all properties of receptive fields in V1 scale with preferred spatial wavelength. Spatial-wavelength independence of the linking field implies a constant spatial range of signal coupling between neurons with different preferred spatial wavelengths. This might be important for encoding extended broad-band visual features such as edges.</p