SIMULATION OF A NOVEL MEDIATED OXYCOMBUSTION SYSTEM

Global warming and climate changing are serious problems challenging humanity, therefore important steps needed to be taking to neutralize such challenge. From the last century huge amount of carbon dioxide released to atmosphere cause huge damages to our globe. Technologies such as oxycombustion and chemical looping combustion had been discussed to capture and sequestration carbon dioxide at lower cost. Separation air from fuel using chemical looping or separation nitrogen from air using oxygen transport membrane (OTM) then combust pure oxygen with fuel are the main step to capture carbone dioxide in less expensive method. Each technology had its own drawback, therefore, to overcome these drawbacks an integrated system is proposed combined oxycombustion, chemical looping and OTM technologies into one system. This work aimed to model and simulate an integrated system in single reactor using liquid Antimony and Antimony trioxide as an oxygen carrier to pick up oxygen from the OTM and reduce fuel using natural circulation due to density difference between metal and metal oxide. Heat is being released inside the reactor due to exothermic oxidation reaction and temperature is increased. The temperature profile is studied in all reactor zones with respect to oxidation and reduction rate, operation temperature, metal viscosity and radiation effect. The result show that the system had a good potential to transfer heat generated from the oxidation and transfer to other zones, in which heat can be utilized and been used for heating water or generate steam

Theoretical study on molten alkali carbonate interfaces

The properties and structure of relevant interfaces involving molten alkali carbonates are studied using molecular dynamics simulation. Lithium carbonate and the Li/Na/K carbonate eutectic mixture are considered. Gas phases composed of pure CO2 or a model flue gas mixture are analyzed. Similarly, the adsorption of these gas phases on graphene are studied, showing competitive CO2 and N2 adsorption that develops liquid-like layers and damped oscillation behavior for density. The interaction of the studied carbonates with graphene is also characterized by development of adsorption layers through strong graphene–carbonate interactions and the development of hexagonal lattice arrangements, especially for lithium carbonate. The development of molten salts–vacuum interfaces is also considered, analyzing the ionic rearrangement in the interfacial region. The behavior of the selected gas phases on top of molten alkyl carbonate is also studied, showing the preferential adsorption of CO2 molecules when flue gases are considered.European Union’s H2020- MSCA-RISE-2016-CO2MPRISE-73487

Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced energy conversion systems. Part 3: Direct energy conversion cycles

For abstract, see N76-23680

Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 3: Gasification, process fuels, and balance of plant

Results are presented of an investigation of gasification and clean fuels from coal. Factors discussed include: coal and coal transportation costs; clean liquid and gas fuel process efficiencies and costs; and cost, performance, and environmental intrusion elements of the integrated low-Btu coal gasification system. Cost estimates for the balance-of-plant requirements associated with advanced energy conversion systems utilizing coal or coal-derived fuels are included

Dopant site selectivity in BaCe0.85M0.15O3-δ by extended x-ray absorption fine structure

Rare earth doped BaCeO3 has been widely investigated as a proton conducting material. Trivalent dopants are generally assumed to fully occupy the Ce4+-site, and thereby introduce oxygen vacancies into the perovskite structure. Recent studies indicate the possibility of partial dopant incorporation onto the Ba2+-site concomitant with BaO evaporation, reducing the oxygen vacancy content. Because proton incorporation requires, as a first step, the generation of oxygen vacancies such dopant partitioning is detrimental to protonic conductivity. A quantitative Extended X-ray Absorption Fine Structure (EXAFS) study of BaCe0.85M0.15O3-δ (M=Yb,Gd) is presented here along with complementary x-ray powder diffraction and electron probe chemical analyses. The EXAFS results demonstrate that as much as 4.6% of the ytterbium and 7.2% of the gadolinium intended for incorporation onto the Ce site, in fact, resides on the Ba site. The results are in qualitative agreement with the diffraction and chemical analyses, which additionally show an even greater extent of Nd incorporation on the Ba site

The Tidal Disruption of Giant Stars and Their Contribution to the Flaring Supermassive Black Hole Population

Sun-like stars are thought to be regularly disrupted by supermassive black holes (SMBHs) within galactic nuclei. Yet, as stars evolve off the main sequence their vulnerability to tidal disruption increases drastically as they develop a bifurcated structure consisting of a dense core and a tenuous envelope. Here we present the first hydrodynamic simulations of the tidal disruption of giant stars and show that the core has a substantial influence on the star's ability to survive the encounter. Stars with more massive cores retain large fractions of their envelope mass, even in deep encounters. Accretion flares resulting from the disruption of giant stars should last for tens to hundreds of years. Their characteristic signature in transient searches would not be the $t^{-5/3}$ decay typically associated with tidal disruption events, but a correlated rise over many orders of magnitude in brightness on months to years timescales. We calculate the relative disruption rates of stars of varying evolutionary stages in typical galactic centers, then use our results to produce Monte Carlo realizations of the expected flaring event populations. We find that the demographics of tidal disruption flares are strongly dependent on both stellar and black hole mass, especially near the limiting SMBH mass scale of $\sim 10^8 M_\odot$. At this black hole mass, we predict a sharp transition in the SMBH flaring diet beyond which all observable disruptions arise from evolved stars, accompanied by a dramatic cutoff in the overall tidal disruption flaring rate. Black holes less massive than this limiting mass scale will show observable flares from both main sequence and evolved stars, with giants contributing up to 10% of the event rate. The relative fractions of stars disrupted at different evolutionary states can constrain the properties and distributions of stars in galactic nuclei other than our own.Comment: 18 pages, 18 figures, submitted to Ap

The isolation and purification of chemical constituents of 'Croton megalocarpus' Hutch husks

Croton is a genus that is part of the Euphorbiaceae family. Croton is widely used in traditional medicine in a number of African countries such as Kenya, Tanzania, Uganda, Sudan, Mozambique and Zambia. Members of the Croton have been reported to treat malaria, diabetes, intestinal worms, influenza and arthritis along with other conditions. However, Croton megalocarpus Hutch is a species that is redominately found in Kenya. C. megalocarpus is regularly processed in the Croton factory that is situated in Kenya. The company that processes the nuts of C. megalocarpus is named Eco Fuels Kenya. The by-products from C. megalocarpus seed oil extraction includes fruit husks from the de-husking process and seed cake resulting from cold pressing of the oil. The purpose of this study is to see whether the husks of C. megalocarpus possess interesting compounds and to determine the safety of these compounds for alternative use. Chemical constituents found in the husks of C. megalocarpus, and various extracts obtained from the husks, seeds and fruit cake were tested for their cytotoxic effects against FM-55 human melanoma cells and mushroom tyrosinase inhibition effects. Extracts were prepared using hexane, dichloromethane and methanol solvents. The hexane extract of the husks produced an oil that had a similar profile to the cold pressed C. megalocarpus seed oil, the dichloromethane extract mainly exhibited diterpenoids of the labdane, cembrane and kaurane classes of compounds whereas methanol extract was mainly sugars with traces of magnoflorine and trans-4-hydroxyN-methyl-L-proline. The dichloromethane (DCM) extract was chosen for further analysis including additional extracts such as ethyl acetate and dichloromethane extract of Croton vinegar oil and tested for cytotoxic and anti- melanogeni9c properties. Seven compounds were successfully isolated from the dichloromethane extract of the husks of C. megalocarpus and characterised using nuclear magnetic resonance (NMR), high resolution mass spectrometry (HRMS) and infrared spectroscopy (IR). The seven isolated compounds are: trans ozic acid, sartone A, epoxykaurane, epoxychiromodine, vanillin, (-)-(1S*,4S*,10R*)-1,4-dihydroxycembra-2E,7E,11Z-trien20,10-olide and (+)-[1R*,4S*,10R*]-4-hydroxycembra-2E, 7E,11Z-trien-20,10-olide. In this study, the ethyl acetate extract of croton vinegar oil exhibited a tyrosinase inhibition of 59.33% at 20mM concentration. Epoxychiromodine exhibited an inhibition of 26.82% at 20µg/ml and showed to have a higher inhibition rate than the other isolated compounds. The dichloromethane extract of the husks was shown to have a cell viability of 45.62% (P<0.05) at 50µg/ml concentration. Sartone A was shown to have a cell viability of 86.08% (P<0.05) at 50µg/ml. The cytotoxicity and tyrosinase inhibition assay have helped determine the safety and effectiveness of the compounds and extracts that may play a vital role in skin care, skin lightening treatments and cancer treatment

Inorganic polyphosphate as an energy source in tumorigenesis

Indexación ScopusCancer cells have high demands for energy to maintain their exceedingly proliferative growth. However, the mechanism of energy expenditure in cancer is not well understood. We hypothesize that cancer cells might utilize energy-rich inorganic polyphosphate (polyP), as energetic reserve. PolyP is comprised of orthophosphates linked by phosphoanhydride bonds, as in ATP. Here, we show that polyP is highly abundant in several types of cancer cells, including brain tumor-initiating cells (BTICs), i.e., stem-like cells derived from a mouse brain tumor model that we have previously described. The polymer is avidly consumed during starvation of the BTICs. Depletion of ATP by inhibiting glycolysis and mitochondrial ATP-synthase (OXPHOS) further decreases the levels of polyP and alters morphology of the cells. Moreover, enzymatic hydrolysis of the polymer impairs the viability of cancer cells and significantly deprives ATP stores. These results suggest that polyP might be utilized as a source of phosphate energy in cancer. While the role of polyP as an energy source is established for bacteria, this finding is the first demonstration that polyP may play a similar role in the metabolism of cancer cells. Copyright: © 2020 Boyineni et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.https://www.oncotarget.com/article/27838/text

NF-κB: blending metabolism, immunity, and inflammation

The procurement and management of nutrients and ability to fight infections are fundamental requirements for survival. These defense responses are bioenergetically costly, requiring the immune system to balance protection against pathogens with the need to maintain metabolic homeostasis. NF-κB transcription factors are central regulators of immunity and inflammation. Over the last two decades, these factors have emerged as a pivotal node coordinating the immune and metabolic systems in physiology and the etiopathogenesis of major threats to human health, including cancer, autoimmunity, chronic inflammation, and others. In this review, we discuss recent advances in understanding how NF-κB-dependent metabolic programs control inflammation, metabolism, and immunity and how improved knowledge of them may lead to better diagnostics and therapeutics for widespread human diseases