Are Fe based catalysts an upcoming alternative to Ni in CO2 methanation at elevated pressure?

The raise of regenerative but unsteadily produced energy demands a highly flexible way to store the energy for time periods when less energy is produced than consumed. In the current study, it is investigated if catalysts based on environmentally more attractive and less hazardous to health Fe might be able to be considered as an alternative to Ni catalysts in the CO2 methanation at elevated pressure. For this a set of catalysts with 1–10 wt % Fe supported on the zeolite 13X is analysed in CO2 methanation at 1–15 bar. The trends of activity as well as selectivity with varying Fe loading and pressure are presented. Correlation with thorough characterization of the materials shows that a very high dispersion of Fe in octahedral sites within the zeolite is necessary to generate CH4 as the main reaction product and suppress the Fischer–Tropsch activity towards Csingle bondC coupling reactions at elevated pressure. Especially with low Fe loading such as 1 wt % high reaction rates of 42 mmol(CO2)/(mol(Fe)∙s) with a CH4 selectivity of 76 % at 300 °C and 10 bar are obtained. In contrast to that, highly Fe loaded catalysts tend to form increasing amounts of Fischer–Tropsch products at increasing pressure. In addition, highly Fe-loaded catalysts are much more susceptible to destruction of the zeolite under reaction conditions. At the same time, highly loaded catalysts form a Fe3C shell around the remaining support. Hence, avoiding the formation of a Fe3C phase is crucial for high CH4 selectivity. The results presented here therefore show that catalysts with a very high Fe-dispersion in particular can gain considerably in importance as alternatives to Ni-methanation catalysts at elevated pressure

Sulphur tolerant diesel oxidation catalysts by noble metal alloying

A series of Mn-alloyed Pt supported catalysts were investigated for the NO oxidation reaction applied in diesel oxidation catalysts under sulphur-containing conditions. The observed NO oxidation conversion correlated to the Pt amount in the catalyst under sulphur-free conditions. In the presence of SO2 in the feed, the Pt/Al2O3 catalyst heavily deactivated resulting in the lowest performance compared to Mn-alloyed Pt catalysts. Already small amounts of Mn improved the SO2-resistance significantly. Whilst pure Pt/Al2O3 catalyst deactivates fully within the first 30 min under NO oxidation conditions including 300 ppm SO2, an alloy with a Mn to Pt ratio of 1:1 performed with a remarkable high catalytic stability for the NO oxidation over at least 70 h under continuous testing conditions

Analysis of host responses to Mycobacterium tuberculosis antigens in a multi-site study of subjects with different TB and HIV infection states in sub-Saharan Africa.

BACKGROUND: Tuberculosis (TB) remains a global health threat with 9 million new cases and 1.4 million deaths per year. In order to develop a protective vaccine, we need to define the antigens expressed by Mycobacterium tuberculosis (Mtb), which are relevant to protective immunity in high-endemic areas. METHODS: We analysed responses to 23 Mtb antigens in a total of 1247 subjects with different HIV and TB status across 5 geographically diverse sites in Africa (South Africa, The Gambia, Ethiopia, Malawi and Uganda). We used a 7-day whole blood assay followed by IFN-γ ELISA on the supernatants. Antigens included PPD, ESAT-6 and Ag85B (dominant antigens) together with novel resuscitation-promoting factors (rpf), reactivation proteins, latency (Mtb DosR regulon-encoded) antigens, starvation-induced antigens and secreted antigens. RESULTS: There was variation between sites in responses to the antigens, presumably due to underlying genetic and environmental differences. When results from all sites were combined, HIV- subjects with active TB showed significantly lower responses compared to both TST(-) and TST(+) contacts to latency antigens (Rv0569, Rv1733, Rv1735, Rv1737) and the rpf Rv0867; whilst responses to ESAT-6/CFP-10 fusion protein (EC), PPD, Rv2029, TB10.3, and TB10.4 were significantly higher in TST(+) contacts (LTBI) compared to TB and TST(-) contacts fewer differences were seen in subjects with HIV co-infection, with responses to the mitogen PHA significantly lower in subjects with active TB compared to those with LTBI and no difference with any antigen. CONCLUSIONS: Our multi-site study design for testing novel Mtb antigens revealed promising antigens for future vaccine development. The IFN-γ ELISA is a cheap and useful tool for screening potential antigenicity in subjects with different ethnic backgrounds and across a spectrum of TB and HIV infection states. Analysis of cytokines other than IFN-γ is currently on-going to determine correlates of protection, which may be useful for vaccine efficacy trials

Potential of Host Markers Produced by Infection Phase-Dependent Antigen-Stimulated Cells for the Diagnosis of Tuberculosis in a Highly Endemic Area

CITATION: Chegou, N. N. et al. 2012. Potential of host markers produced by infection phase-dependent antigen-stimulated cells for the diagnosis of tuberculosis in a highly endemic area. PLoS ONE, 7(6): e38501, doi:10.1371/journal.pone.0038501.The original publication is available at http://journals.plos.org/plosoneBackground: Recent interferon gamma (IFN-γ)-based studies have identified novel Mycobacterium tuberculosis (M.tb) infection phase-dependent antigens as diagnostic candidates. In this study, the levels of 11 host markers other than IFN-γ, were evaluated in whole blood culture supernatants after stimulation with M.tb infection phase-dependent antigens, for the diagnosis of TB disease. Methodology and Principal Findings: Five M.tb infection phase-dependent antigens, comprising of three DosR-regulon-encoded proteins (Rv2032, Rv0081, Rv1737c), and two resucitation promoting factors (Rv0867c and Rv2389c), were evaluated in a case-control study with 15 pulmonary TB patients and 15 household contacts that were recruited from a high TB incidence setting in Cape Town, South Africa. After a 7-day whole blood culture, supernatants were harvested and the levels of the host markers evaluated using the Luminex platform. Multiple antigen-specific host markers were identified with promising diagnostic potential. Rv0081-specific levels of IL-12(p40), IP-10, IL-10 and TNF-α were the most promising diagnostic candidates, each ascertaining TB disease with an accuracy of 100%, 95% confidence interval for the area under the receiver operating characteristics plots, (1.0 to 1.0). Conclusions: Multiple cytokines other than IFN-γ in whole blood culture supernatants after stimulation with M.tb infection phase-dependent antigens show promise as diagnostic markers for active TB. These preliminary findings should be verified in well-designed diagnostic studies employing short-term culture assays. © 2012 Chegou et al.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0038501Publisher's versio

Potential of novel Mycobacterium tuberculosis infection phase-dependent antigens in the diagnosis of TB disease in a high burden setting

<p>Abstract</p> <p>Background</p> <p>Confirming tuberculosis (TB) disease in suspects in resource limited settings is challenging and calls for the development of more suitable diagnostic tools. Different <it>Mycobacterium tuberculosis (M.tb) </it>infection phase-dependent antigens may be differentially recognized in infected and diseased individuals and therefore useful as diagnostic tools for differentiating between <it>M.tb </it>infection states. In this study, we assessed the diagnostic potential of 118 different <it>M.tb </it>infection phase-dependent antigens in TB patients and household contacts (HHCs) in a high-burden setting.</p> <p>Methods</p> <p>Antigens were evaluated using the 7-day whole blood culture technique in 23 pulmonary TB patients and in 19 to 21 HHCs (total n = 101), who were recruited from a high-TB incidence community in Cape Town, South Africa. Interferon-gamma (IFN-γ) levels in culture supernatants were determined by ELISA.</p> <p>Results</p> <p>Eight classical TB vaccine candidate antigens, 51 DosR regulon encoded antigens, 23 TB reactivation antigens, 5 TB resuscitation promoting factors (rpfs), 6 starvation and 24 other stress response-associated TB antigens were evaluated in the study. The most promising antigens for ascertaining active TB were the rpfs (Rv0867c, Rv2389c, Rv2450c, Rv1009 and Rv1884c), with Areas under the receiver operating characteristics curves (AUCs) between 0.72 and 0.80. A combination of <it>M.tb </it>specific ESAT-6/CFP-10 fusion protein, Rv2624c and Rv0867c accurately predicted 73% of the TB patients and 80% of the non-TB cases after cross validation.</p> <p>Conclusions</p> <p>IFN-γ responses to TB rpfs show promise as TB diagnostic candidates and should be evaluated further for discrimination between <it>M.tb </it>infection states.</p

Katalysatoroptimierung durch Umwandlung einer unerwünschten Phase in eine wertvolle co-basierte Katalysatorvorstufe für eine verbesserte Methanisierung von CO2

Um die Energiewende zu ermöglichen, müsen effiziente und stabile Katalysatoren für die Umwandlung von CO2 mit regenerativem H2 in Energieträger wie Methan (CH4) entwickelt werden. Katalysatoren auf Basis von Co/Al2O3 erfahren eine Deaktivierung unter Reaktionsbedingungen durch Bildung einer sekundären CoAl2O4-Phase. Konventionell wird die Reduzierbarkeit von Co/Al2O3-Katalysatoren durch Zugabe von Edelmetallen erhöht. Ein alternativer Ansatz bietet die Modifikation des Trägers. In der vorliegenden Studie wurde Aluminium durch Mangan in der Form CoAl2xMnxO4 substituiert. Dies ewirkt eine drastische Erhöhung der Reduzierbarkeit des Materials, so dass ausgehend vom Spinell ein deutlich verbesserter Methanisierungskatalysator erhalten wird, der bei 350 °C in der Lage ist, 80% CO2 mit einer Selektivität von über 97% zu Methan umzusetzen. Zusätzlich sinkt die Aktivierungsenergie für die Methanisierung von 94 auf 56 kJ mol–1 durch die Modifikation des Spinells. Mittels XRD, TPR, CO2-TPD, N2-Physisorption und operando DRIFTS-Analysen wird gezeigt, dass sich auch die basischen Oberflächeneigenschaften signifikant ändern, einhergehend mit einer Änderung des Reaktionsmechanismus. Die vorliegende Arbeit stellt einen alternativen und kostengünstigeren Lösungsweg zur Vermeidung der Deaktivierung unter Reaktionsbedingungen durch Optimierung des Reduktionsverhaltens vor

The effect of a stimulation pattern on force and fatigue of paralyzed human quadriceps

The effects of several stimulation patterns at constant duty cycle on isometric and isokinetic knee torque development and fatigue-induced torque decline in electrically stimulated paralyzed human quadriceps were studied. The benefit of optimizing the interpulse intervals (PISi)n comparison to a repetitive train (constant PIS) increased with the number of stimulation pulses. Application of an optimized pattern on sustained intermittent stimulation resulted in higher torque-time integral ("TI) per cycle. The overall loss had a typical exponential decay reaching asymptotic values

Exsolution and integration of nanosized SMART catalysts for next generation SOFC anodes

B1104La-doped strontium titanate (LST) materials are widely recognized among other alternative anodes as good electronic conductors with high tolerance to redox cycles, but with insufficient catalytic activity. However, doping of LST with quasi-stable metal ions (e.g. Ni, Co) allows a selective exsolution of these metals from the bulk onto the materials surface and thus increasing the catalytic activity. Previously we have demonstrated our SMART material concept with selfregeneration effect, in which nano-sized nickel catalyst is repeatedly exsolved from and incorporated back into the La0.2.Sr0.7Ti0.95Ni0.05O3-d (LSTN) perovskite host structure. Nickel nanoparticles are exsolved from LST at SOFC anode conditions and nickel is reincorporated at high pO2, during a redox cycle. This turns redox cycles - the weakness of conventional Ni/YSZ anodes - into an advantage and regenerates the material. The authors present recent advances of the SMART material catalysts based on LSTN. We demonstrate that upon harsh heat treatment (T = 1200°C) depending on the location and site at least three types of nickel particles being generated LSTN: a) fine particles with presumably high catalytic activity (dp 150 nm), generated on the facets of grains are reversibly incorporated into the LSTN host matrix (Fig. 1), while those large ones located at the grain boundaries underwent an oxidation to NiO. Temperature programmed reduction has proven unchanged REDOX reversibility of LSTN materials upon 9 redox cycles a temperature of 900°C, suggesting catalytic reversibility

Endocrine Resistance in Breast Cancer: The Role of Estrogen Receptor Stability

Therapy of hormone receptor positive breast cancer (BCa) generally targets estrogen receptor (ER) function and signaling by reducing estrogen production or by blocking its interaction with the ER. Despite good long-term responses, resistance to treatment remains a significant issue, with approximately 40% of BCa patients developing resistance to ET. Mutations in the gene encoding ERα, ESR1, have been identified in BCa patients and are implicated as drivers of resistance and disease recurrence. Understanding the molecular consequences of these mutations on ER protein levels and its activity, which is tightly regulated, is vital. ER activity is in part controlled via its short protein half-life and therefore changes to its stability, either through mutations or alterations in pathways involved in protein stability, may play a role in therapy resistance. Understanding these connections and how ESR1 alterations could affect protein stability may identify novel biomarkers of resistance. This review explores the current reported data regarding posttranslational modifications (PTMs) of the ER and the potential impact of known resistance associated ESR1 mutations on ER regulation by affecting these PTMs in the context of ET resistance