196 research outputs found
Studies for the Loss of Atomic and Molecular Species from IO
No full textThe general objective of this project has been to advance our theoretical understanding of lo's atmosphere and how various atomic and molecular species are lost from this atmosphere and are distributed in the circumplanetary environment of Jupiter. This grant has provided support for the activities of Dr. Michael Combi at the University of Michigan to serve as a small part in collaboration with a larger project awarded to Atmospheric & Environmental Research, Inc., with primary principal investigator Dr. William H. Smyth. Dr. Combi is the Principal Investigator and Project Manager for the Michigan grant NAG5-6187. This Michigan grant has provided for a continuation of a collaboration between Drs. Smyth and Combi in related efforts beginning in 1981, and with the object to develop and apply sophisticated theoretical models to interpret and to relate a number of new and exciting observations for the atmospheric gases of the satellite. The ability to interpret and then to relate through the theoretical fabric a number of these otherwise independent observations are a central strength of this program. This comprehensive approach provides a collective power, extracting more from the sum of the parts and seeing beyond various limitations that are inherent in any one observation. Although the approach is designed to unify, the program is divided into well-defined studies for the likely dominant atmospheric gases involving species of the SO2 family (SO2, SO, O2, S and O) and for the trace atmospheric gas atomic sodium and a likely escaping molecular ion NaX(+) (where Na(X) is the atmospheric molecule and X represents one or more atoms).Attachments: IO's sodium corona and spatially cloud: a consistent flux speed distribution. and Io's plasma environment during the Galileo flyby: global three-dimensional MHD modeling with adaptive mesh refinement
A Massively Parallel Hybrid Dusty-Gasdynamics and Kinetic Direct Simulation Monte Carlo Model for Planetary Applications
No full textIn order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic (MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important. At the University of Michigan we have an established base of experience and expertise in numerical simulations based on particle codes which address these physical regimes. The Principal Investigator, Dr. Michael Combi, has over 20 years of experience in the development of particle-kinetic and hybrid kinetichydrodynamics models and their direct use in data analysis. He has also worked in ground-based and space-based remote observational work and on spacecraft instrument teams. His research has involved studies of cometary atmospheres and ionospheres and their interaction with the solar wind, the neutral gas clouds escaping from Jupiter s moon Io, the interaction of the atmospheres/ionospheres of Io and Europa with Jupiter s corotating magnetosphere, as well as Earth s ionosphere. This report describes our progress during the year. The contained in section 2 of this report will serve as the basis of a paper describing the method and its application to the cometary coma that will be continued under a research and analysis grant that supports various applications of theoretical comet models to understanding the inner comae of comets (grant NAGS- 13239 from the Planetary Atmospheres program)
Combi-terminal: Studie naar het toepassen van het combi-terminal concept op een moderne marine terminal
No full textDe kaden bij de marine containerterminals in Noord-Westeuropa hebben een lage bezettingsgraad. De investeringen in de kaden leveren daardoor een laag rendement op. Als oplossing voor dit probleem is het combi-terminal concept naar voren gekomen in de voorgaande studie "Innovatief kade-concept". Bij dit concept worden naast containerschepen ook andere zeeschepen aan de kade behandeld welke een ander produkt aanvoeren. Hiermee zijn de bezettingsgraden te verhogen en het rendement van de kade. Het concept is uitgewerkt voor een containerterminal in de Rotterdamse haven welke in 2007 operationeel moet zijn om de doorgroeiende containerstroom op te vangen. Een dergelijke terminal moet voldoen aan de nieuwste eisen van de gebruiker, met name de containerrederijen. De verwachting is dat deze met 8.000 TEU schepen de belangrijkste lijndiensten gaan onderhouden en eisen dat deze niet langer dan 24 uur in een haven mogen verblijven. Vanuit deze eis volgt de belangrijkste eis aan terminals, een ligplaatsproduktie zien te realiseren van 250 containers per uur. Door per ligplaats 5 twee-kat-kranen in te zetten welke geplaatst zijn op een verhoogde achterkraanbaan kan aan deze eis worden voldaan. Het rendement van een kade neemt dan ook toe doordat er 2,5 keer zoveel containers over de kade gaan in vergelijking met de huidige kaden waar 100 containers per uur per ligplaats over de kade gaan. De terminal moet daarnaast wel investeren in een opslagconcept met een hogere in- en uitslagcapaciteit. Binnen het gekozen concept wordt het rendement verder verhoogd door ook chemie- en olieprodukten over te slaan op de kade. Daarnaast is ook een opslag in de kade geïntegreerd waarin chemie- en/of olieprodukten kunnen worden opgeslagen. Hiermee kunnen ook extra inkomsten per meter kade binnenkomen. Op de Maasvlakte is een opslag in de kade het beste te realiseren door het toepassen van een ontlastconstructie. Deze constructie kan in een open bouwput gebouwd worden als er nog geen activiteiten plaatsvinden op het terminalterrein. De kosten van een dergelijke kade kunnen worden opgebracht door investeringen die gedaan moeten worden voor gelijkwaardige voorzieningen. De overlast voor de containerterminal is minimaal doordat de voorzieningen boven de grond beperkt blijven. Alleen een verhoogd platform met daarop laadarmen voor het behandelen van de tankers staat bovengronds per ligplaats opgesteld. Bij de terminal moet wel een aparte ondiepwaterkade worden aangelegd voor de behandeling van de binnenvaart die niet meer aan de zeekade wordt behandeld. De kadecapaciteit die over is wordt ingezet voor de behandeling van olie- en chemietankers. Nader onderzoek naar de bezetting van de kade en de te verwachten wachttijd en is noodzakelijk om de haalbaarheid met zekerheid vast te stellen. Afhankelijk daarvan kunnen ook de eisen worden vastgesteld die aan de containerschepen en de tankers worden gesteld. Als er dan een bezettingsgraad van 60% valt te realiseren is het concept van de combi-terminal haalbaar, ook op een moderne marine containerterminal.Hydraulic EngineeringCivil Engineering and Geoscience
COMBI-r: A Prospective, Non-Interventional Study of Dabrafenib Plus Trametinib in Unselected Patients with Unresectable or Metastatic BRAF V600-Mutant Melanoma
No full text Combined BRAF/MEK-inhibition constitutes a relevant treatment option for BRAF-mutated advanced melanoma. The prospective, non-interventional COMBI-r study assessed the effectiveness and tolerability of the BRAF-inhibitor dabrafenib combined with the MEK-inhibitor trametinib in patients with advanced melanoma under routine clinical conditions. Progression-free survival (PFS) was the primary objective, and secondary objectives included overall survival (OS), disease control rate, duration of therapy, and the frequency and severity of adverse events. This study enrolled 472 patients at 55 German sites. The median PFS was 8.3 months (95%CI 7.1–9.3) and the median OS was 18.3 months (14.9–21.3), both tending to be longer in pre-treated patients. In the 147 patients with CNS metastases, PFS was similar in those requiring corticosteroids (probably representing symptomatic patients, 5.6 months (3.9–7.2)) compared with those not requiring corticosteroids (5.9 months (4.8–6.9)); however, OS was shorter in patients with brain metastases who received corticosteroids (7.8 (6.3–11.6)) compared to those who did not (11.9 months (9.6–19.5)). The integrated subjective assessment of tumor growth dynamics proved helpful to predict outcome: investigators’ upfront categorization correlated well with time-to-event outcomes. Taken together, COMBI-r mirrored PFS outcomes from other prospective, observational studies and confirmed efficacy and safety findings from the pivotal phase III COMBI-d/-v and COMBI-mb trials. Novartis Pharma Gmb
Danube River Development Strategy: Interim Report
No full textThe Danube is an essential Inland Water Transport (IWT) corridor, particularly for the hinterland connection for the Port of Constantza. This port became one of the largest and busiest ports on the Black Sea, due to its strategic location at the cross roads of Europe and Asia and due to its capacity to handle large volumes of different types of cargoes. With the ongoing economic reforms in Romania it is expected that the Port of Constantza will develop into a gateway for Eastern and Central Europe and efficient IWT hinterland connections are therefore required. The project "Danube River Development Strategy" aims to formulate a strategy and to define measures to increase the competitive position of IWT and to improve the navigability of the Romanian stretch of the Danube between the Iron Gates II and Giurgeni. The approach of the project can be characterized as strategy formulation to create a high capacity transport corridor at minimum investment costs. The project comprises two phases, i.e. River Status Phase and Strategy Development Phase. The first phase of the project has been completed in September 1994 with the submission of the River Status Report, which describes the present status of the Danube river followed by the generation of alternative development strategies for the Danube. In the second project phase selected strategies are analyzed followed by the selection of the preferred river development strategy. This Interim Report for the Strategy Development Phase includes the analyses of the various alternative development strategies. The report will be presented to and discussed with the Romanian authorities to select and further define the preferred development strategy. This preferred strategy will then be further analysed and reported in the Draft Final Report. The main objective of the Danube River Development Strategy project is to improve the navigation conditions of the Romanian section of the Danube between the Iron Gates II (rkm 869) and Giurgeni (rkm 239) in order to create a competitive IWT hinterland connection for the Port of Constantza. Various alternative development strategies have been considered. The strategies are rated on multiple criteria, where it appeared that all considered strategies are economically viable. The alternatives combi-c3 and combi-c4 appeared to have the best results. For description of all the alternatives we refer to the report.Danube River Development Strateg
Combi-CLEAs of glucose oxidase and catalase for conversion of glucose to gluconic acid eliminating the hydrogen peroxide to maintain enzyme activity in a bubble column reactor
No full text© The Author(s).In this study combined cross-linked aggregates of catalase from bovine liver and glucose-oxidase from Aspergillus niger were prepared, and the effects of the precipitant and crosslinking agents, as well as the use of bovine serum albumin (BSA) as a feeder protein, on enzyme immobilization yield and thermal stability of both enzymes, were evaluated. Combi- crosslinking of enzyme aggregates (CLEAs) prepared using dimethoxyethane as precipitant, 25 mM glutaraldehyde and BSA/enzymes mass ratio of 5.45 (w/w), exhibited the highest enzyme activities and stabilities at 40 °C, pH 6.0, and 250 rpm for 5 h. The stability of both immobilized enzymes was fairly similar, eliminating one of the problems of enzyme coimmobilization. Combi-CLEAs were used in gluconic acid (GA) production in a bubble column reactor operated at 40 °C, pH 6.0 and 10 vvm of aeration, using 26 g L−1 glucose as the substrate. Results showed conversion of around 96% and a reaction course very similar to the same process using free enzymes. The operational half-life was 34 h, determined from kinetic profiles and the first order inactivation model. Combi-CLEAs of glucose-oxidase and catalase were shown to be a robust biocatalyst for applications in the production of gluconic acid from glucose.This work was supported by the National Council for Scientific and Technological Development (CNPq) (grants #141647/2013-2 and #402850/2013-0), and in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–Brazil (CAPES)–Finance Code 001, and by the Comunidad Autónoma de Madrid (project Ref. IND2017/IND-7640) and MINECO from Spanish Government, (project number CTQ2017-86170-R).Peer reviewe
Kinetic simulation of neutral∕ionized gas and electrically charged dust in the coma of comet 67P∕Churyumov-Gerasimenko
No full textThe cometary coma is a unique phenomenon in the solar system being a planetary atmosphere influenced by little or no gravity. As a comet approaches the sun, the water vapor with some fraction of other gases sublimate, generating a cloud of gas, ice and other refractory materials (rocky and organic dust) ejected from the surface of the nucleus. Sublimating gas molecules undergo frequent collisions and photochemical processes in the near‐nucleus region. Owing to its negligible gravity, comets produce a large and highly variable extensive dusty coma with a size much larger than the characteristic size of the cometary nucleus. The Rosetta spacecraft is en route to comet 67P/Churyumov‐Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. Both, interpretation of measurements and safety consideration of the spacecraft require modeling of the comet’s dusty gas environment. In this work we present results of a numerical study of multispecies gaseous and electrically charged dust environment of comet Chyuryumov‐Gerasimenko. Both, gas and dust phases of the coma are simulated kinetically. Photolytic reactions are taken into account. Parameters of the ambient plasma as well as the distribution of electric/magnetic fields are obtained from an MHD simulation [1] of the coma connected to the solar wind. Trajectories of ions and electrically charged dust grains are simulated by accounting for the Lorentz force and the nucleus gravity
Designing an enzyme assembly line for green cascade processes using bio-orthogonal chemistry
No full textTwo non-canonical amino acids (ncAAs) with bio-orthogonal reactive groups, namely, p-azido-l-phenylalanine (p-AzF) and p-propargyloxy-l-phenylalanine (p-PaF), were genetically inserted into an aldo-keto reductase (AKR) and an alcohol dehydrogenase (ADH), respectively, at two preselected sites for each enzyme. The variants were expressed in the genome recoded bacterium Escherichia coli C321.ΔA. Supernatants of the individual cell lysates were subsequently mixed to produce orderly combi-crosslinked enzymes (O-CLEs) of AKR and ADH by co-polymerization of the two variants through their reactive bio-orthogonal groups. The site-specific cross-linked enzymes (S-CLEs) and cross-linked enzyme aggregates (CLEAs) were produced using dibenzocycloocta-4a,6a-diene-5,11-diyne (DBA) and glutaraldehyde as the crosslinking agent, respectively. The catalytic efficiencies of the O-CLEs, S-CLEs and combi-CLEAs were determined using the water soluble dihydro-4, 4-dimethyl-2, 3-furandione as a surrogate substrate in aqueous solution at 37 °C. The O-CLEs exhibited the highest catalytic efficiency (Kcat/KM = 11.36 S−1 mM−1) that was 4.24 and 22.27 times that of S-CLEs and combi-CLEAs, respectively. In the asymmetric cascade synthesis of (R)-1-(2-chlorophenyl) ethanol the product yield after 14 h using the O-CLEs, S-CLEs and the combi-CLEAs was 93%, 55% and 16%, respectively. Moreover, high activities and selectivity (ee > 99.99%) were maintained at high substrate concentrations in prolonged operation.BT/Biocatalysi
Development of a numerical kinetic model and its application to dusty gas cometary atmospheres.
No full textThis dissertation presents a newly developed model of inner and outer comae and results of its application for comets Borrelly, Hyakutake and Churyumov-Gerasimenko. A kinetic approach is the most convenient one to describe significantly different flow regimes and processes occurring in a coma. During the work on the dissertation a general-purpose multiphase kinetic flow solver that can be applied to a wide range of multidimensional problems was developed. The numerical tool is implemented on massively parallel computers and can be used for simulation of a multi-species gas flow on an unstructured mesh with an arbitrarily complex geometry of the boundary and boundary conditions. The new element that makes the newly developed model different from other available models of cometary comae is the kinetic representation of the dust phase in a flow that also allows simulation of an extended source of volatiles in the coma. During this study the structure of cometary comae was simulated starting from the surface of the nucleus and extending up to 106 km. Six species (H2O, CO, OH, H2, O, H) were included into the model. The intermolecular momentum exchange, energy exchange between internal degrees of freedom and radiative cooling were taken into consideration. The coma model takes photochemical processes into account. Numerical study indicated that the combination of photodissociation and momentum exchange in the collisionally transitional region results in significant variations of macroscopic parameters in the gas phase of the outer coma. Nonsublimating dust and sublimating icy grains were included into the model as the second phase. The dusty-gas environment of comet Borrelly was modeled. It was used to analyze images taken with the MICAS camera on the Deep Space 1 spacecraft. The study of the grain acceleration in the innermost coma was performed. It was found that the grains reach their terminal velocities within 10 radii of the nucleus. Sublimation of icy grains contributes to the extended source of volatiles in the coma. The study of variation of icy grains characteristic size and mean radial velocity with the distance from the nucleus was performed. The influence of the extended source on the distribution of macroscopic parameters in a coma was studied for the case of comet Hyakutake. It was found that the extended source significantly influences the distribution of the radial velocity and temperature of the gas phase in the coma. A model study of the Rosetta mission target comet Churyumov-Gerasomenko was performed to specify the gas environment of the comet throughout the mission from the initial encounter to the perihelion.PhDAstronomyPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/125901/2/3224762.pd
The magnetohydrodynamics of cometary plasma.
No full textUnderstanding of the cometary plasma environment, an ideal laboratory for magnetohydrodynamic (MHD) study, has great value in plasma physics. This dissertation presents a collection of 3-D global mass-loaded ideal MHD studies of this environment with a multi-scale grid system resolving both the bow shock and contact surface. Using the single and multi-species versions of this model as well as steady-state and time-dependent solutions, the dynamic structures, mass loading process, tail dynamics, and ion chemistry are advanced through theoretical parameter studies and direct model-data comparisons. With the single species version of this model, the importance of mass loading on the appearance of the plasma distribution, marked by the density and pressure distribution, as well as the dynamic structures, are presented as a good reference for future studies. The density and velocity measurements of comet 19P/Borrelly by the Deep Space 1 spacecraft are reproduced by our MHD model. The role of the neutral density distribution, which is the source of mass loading, on the plasma distribution, is advanced via such comparisons. Predictions of the plasma environment around comet 67P/Churyumov-Gerasimenko are also provided for four key locations during the Rosetta mission. The dynamic evolution of the cornetary plasma tail is also presented in the study of disconnection events (DEs). With heliospheric current sheet (HCS) crossings represented by a tangential discontinuity, our model reproduced the real-time evolution images of such DEs accompanied by magnetic reconnections. A CME-comet interaction has also been studied for the first time with reasonable comparison to some images. The first three-dimensional multi-species MHD model has been applied to the solar wind-comet interaction. In addition to reproducing the 1-species result, good agreement with Giotto proton densitv measurements can be obtained by estimating the hydrogen neutral distribution with the Haser model. The 6-species model considers the water group and CO group chemistry and suggests that in the inner coma, elastic collisions between ions and neutrals are more efficient in momentum transfer than the charge-exchange processes, which creates the major ion, H3O+. Compared with the single-species MHD model, such a 6-species MHD model is better able to provide the locations of cometopause and collisionopause.PhDAstronomyPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/126729/2/3276195.pd
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