In-Situ Investigation of Gas Phase Radical Chemistry in the Catalytic Partial Oxidation of Methane on Pt

The catalytic partial oxidation of methane on platinum was studied in situ under atmospheric pressure and temperatures between 1000 and 1300 °C. By combining radical measurements using a molecular beam mass spectrometer and threshold ionization with GC, GC-MS and temperature profile measurements it was demonstrated that a homogeneous reaction pathway is opened at temperatures above 1100 °C, in parallel to hetero-geneous reactions which start already at 600 °C. Before ignition of gas phase chemistry, only CO, H2, CO2 and H2O are formed at the catalyst surface. Upon ignition of gas chemistry, CH3⋅ radicals, C2 coupling products and traces of C3 and C4 hydrocarbons are observed. Because the formation of CH3⋅ radicals correlates with the formation of C2 products it can be concluded that C2 products are formed by coupling of methyl radicals in the gas phase followed by dehydrogenation reactions. This formation pathway was predicted by numerical simulations and this work presents an experimental confirmation under high temperature atmospheric pressure conditions

Molecular Beam Mass Spectrometer Equipped with a Catalytic Wall Reactor for In Situ Studies in High Temperature Catalysis Research

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Blood group determinates incidence for pancreatic cancer in Germany

Background: Genetic risk factors for sporadic pancreatic cancer are largely unknown but actually under high exposure. Findings of correlations between the AB0 blood group system (Chromosome 9q34,1-q34,2) and the risk of pancreatic cancer (PC) in patients from Asia, America and south Europe have already been published. So far it is unclear, whether this correlation between blood group an PC incidence can be found in German patients as well. Methods: One hundred and sixty-six patients who underwent a resection of PC were evaluated in a period between 2000 and 2010. Blood group reference distribution for the German population is given as: 0: 41%; A: 43%; B: 11%; AB: 5%; Rhesus positive: 85%; Rhesus negative: 15%. Analyses were done using the non-parametric Chi(2)-test (p-value two sided; SPSS 19.0). Results: Median age was 62 (34-82) years. Gender: female 73/44%; male: 93/56%. Observed blood group proportions: 0: 43 (25.9%)/A: 94 (56.6%)/B: 16 (9.6%)/AB: 13 (7.8%)/Rhesus positive: 131 (78.9%)/negative: 35 (21.1%). We detected a significant difference to the German reference distribution of the AB0 system (Chi(2) 19.34, df 3, p < 0.001). Rhesus factor has no impact on AB0-distribution (Chi(2) 4.13, df 3, p = 0.25), but differs significantly from reference distribution-probably due to initial AB0-variation (Chi(2) 4.82, df 1, p = 0.028). The odds ratio for blood group A is 2.01 and for blood group 0 is 0.5. Conclusions: The incidence of PC in the German cohort is highly associated with the AB0-system as well. More patients with blood group A suffer from PC (p < 0.001) whereas blood group 0 was less frequent in patients with PC (p < 0.001). Thus, our findings support the results from other non-German surveys. The causal trigger points of this carcinogenesis correlation are still not known

Heterogeneous–Homogeneous Catalytic Partial Oxidations Investigated by Molecular Beam Mass Spectrometry

Heterogeneous catalytic reactions are often insufficiently described by surface reaction steps only; gas phase contributions are neglected. Surface and gas phase reaction steps can take place simultaneously and are coupled by exchange of energy and reaction intermediates. Catalytic partial oxidations are suspected to proceed via combined heterogeneous–homogeneous mechanisms because of high reaction temperatures and the diradical oxygen as reactant. Gas phase radicals are thought to be key intermediates, but there is little understanding of mechanistic details [1]. To study the mechanism of such reactions we have developed a Molecular Beam Mass Spectrometer (MBMS) equipped with a high temperature catalytic wall reactor

Keeping the driver in the loop through semi-automated or manual lane changes in conditionally automated driving

In the current study we investigated if drivers of conditionally automated vehicles can be kept in the loop through lane change maneuvers. More specifically, we examined whether involving drivers in lane-changes during a conditionally automated ride can influence critical take-over behavior and keep drivers' gaze on the road. In a repeated measures driving simulator study (n = 85), drivers drove the same route three times, each trial containing four lane changes that were all either (1) automated, (2) semi-automated or (3) manual. Each ride ended with a critical take-over situation that could be solved by braking and/or steering. Critical take-over reactions were analyzed with a linear mixed model and parametric accelerated failure time survival analysis. As expected, semi-automated and manual lane changes throughout the ride led to 13.5% and 17.0% faster maximum deceleration compared to automated lane changes. Additionally, semi-automated and manual lane changes improved the quality of the take-over by significantly decreasing standard deviation of the steering wheel angle. Unexpectedly, drivers in the semi-automated condition were slowest to start the braking maneuver. This may have been caused by the drivers' confusion as to how the semi-automated system would react. Additionally, the percentage gaze off-the-road was significantly decreased by the semi-automated (6.0%) and manual (6.6%) lane changes. Taken together, the results suggest that semi-automated and manual transitions may be an alarm-free instrument which developers could use to help maintain drivers' perception-action loop and improve automated driving safety

Quantum magneto-oscillations in a two-dimensional Fermi liquid

Quantum magneto-oscillations provide a powerfull tool for quantifying Fermi-liquid parameters of metals. In particular, the quasiparticle effective mass and spin susceptibility are extracted from the experiment using the Lifshitz-Kosevich formula, derived under the assumption that the properties of the system in a non-zero magnetic field are determined uniquely by the zero-field Fermi-liquid state. This assumption is valid in 3D but, generally speaking, erroneous in 2D where the Lifshitz-Kosevich formula may be applied only if the oscillations are strongly damped by thermal smearing and disorder. In this work, the effects of interactions and disorder on the amplitude of magneto-oscillations in 2D are studied. It is found that the effective mass diverges logarithmically with decreasing temperature signaling a deviation from the Fermi-liquid behavior. It is also shown that the quasiparticle lifetime due to inelastic interactions does not enter the oscillation amplitude, although these interactions do renormalize the effective mass. This result provides a generalization of the Fowler-Prange theorem formulated originally for the electron-phonon interaction.Comment: 4 pages, 1 figur

Parenteral nutrition support for patients with pancreatic cancer. Results of a phase II study

<p>Abstract</p> <p>Background</p> <p>Cachexia is a common problem in patients (pts) suffering from upper gastrointestinal cancer. In addition, most of these patients suffer from malabsorption and stenosis of the gastrointestinal tract due to their illness. Various methods of supplementary nutrition (enteral, parenteral) are practised. In patients with advanced pancreatic cancer (APC), phase angle, determined by bio-electrical impedance analysis (BIA), seems to be a survival predictor. The positive influence of BIA determinate predictors by additional nutrition is currently under discussion.</p> <p>Methods</p> <p>To examine the impact of additional parenteral nutrition (APN) we assessed outpatients suffering from APC and progressive cachexia. The assessment based on the BIA method. Assessment parameters were phase angle, ECM/BCM index (ratio of extracellular mass to body cell mass), and BMI (body mass index). Patients suffering from progressive weight loss in spite of additional enteral nutritional support were eligible for the study.</p> <p>Results</p> <p>Median treatment duration in 32 pts was 18 [8-35] weeks. Response evaluation showed a benefit in 27 pts (84%) in at least one parameter. 14 pts (43.7%) improved or stabilised in all three parameters. The median ECM/BCM index was 1.7 [1.11-3.14] at start of APN and improved down to 1.5 [1.12-3.36] during therapy. The median BMI increased from 19.7 [14.4-25.9] to 20.5 [15.4-25.0]. The median phase angle improved by 10% from 3.6 [2.3-5.1] to 3.9 [2.2-5.1].</p> <p>Conclusions</p> <p>We demonstrated the positive impact of APN on the assessed parameters, first of all the phase angle, and we observed at least a temporary benefit or stabilisation of the nutritional status in the majority of the investigated patients. Based on these findings we are currently investigating the impact of APN on survival in a larger patient cohort.</p> <p>Trial registration</p> <p>ClinicalTrials.gov Identifier: NCT00919659</p

Dynamical N-body Equlibrium in Circular Dilaton Gravity

We obtain a new exact equilibrium solution to the N-body problem in a one-dimensional relativistic self-gravitating system. It corresponds to an expanding/contracting spacetime of a circle with N bodies at equal proper separations from one another around the circle. Our methods are straightforwardly generalizable to other dilatonic theories of gravity, and provide a new class of solutions to further the study of (relativistic) one-dimensional self-gravitating systems.Comment: 4 pages, latex, reference added, minor changes in wordin

Maternal health and the placental microbiome

Over the past decade, the role of the microbiome in regulating metabolism, immune function and behavior in humans has become apparent. It has become clear that the placenta is not a sterile organ, but rather has its own endogenous microbiome. The composition of the placental microbiome is distinct from that of the vagina and has been reported to resemble the oral microbiome. Compared to the gut microbiome, the placental microbiome exhibits limited microbial diversity. This review will focus on the current understanding of the placental microbiota in normal healthy pregnancy and also in disease states including preterm birth, chorioamnionitis and maternal conditions such as obesity, gestational diabetes mellitus and preeclampsia. Factors known to alter the composition of the placental microbiota will be discussed in the final part of this review