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  • 1
    Electronic Resource
    Electronic Resource
    Ultrasonic degradation of macromolecules in solution. Study of degradation kinetics by estimation of free-radical scavenger DPPH and solution viscosity measurementsProd. No. 1357 (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1089-1098 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of degradation of butyl rubber in two solvents, cyclohexane and toluene, was studied by two independent techniques: viscosity measurements and free-radical estimation as a function of DPPH consumed. The general shape of the rate curves in the two cases is similar, but not identical. The rate given by estimation of DPPH is faster than that obtained from solution viscosity data. This has been attributed to the inherent limitations of the two methods for the quantitative determination of the number of breaks occurring in the polymer molecules. The rate is also reduced as the viscosity of the solution medium is increased, which may be correlated with the reduction of the cavitation effect responsible for degradation. The degradation rates in two solvent media initially having the same viscosity were unequal. This may be due to different solvent-solute characteristics, which means that the viscosity and cavitation change to different extents in the two cases throughout the course of degradation. The limiting degree of Polymerization (DP)∞ obtained after prolonged irradiation has been found to be dependent on parameters such as intensity of irradiation, solution viscosity, and initial DP of the molecules.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1966.070100801
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  • 2
    Electronic Resource
    Electronic Resource
    Rapid analysis of some coinage, jewellery, aluminium bronze and ternary alloys by the ring oven technique (1965)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 28 (1965), S. 137-140 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Schemes have been worked out for the quantitative separation and subsequent determination of the constituents in a number of alloys containing Au—Cu, Cu—Al, Fe—Au and Fe—Cu—Al by the ring oven technique. Gold is migrated to the ring zone by extraction with n-butanol at pH = 1.5 and iron or copper with acetylacetone. Aluminium is moved to the ring zone by acidified ethanol.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19650280306
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  • 3
    Electronic Resource
    Electronic Resource
    Polymerization of N-vinylearbazole with vanadium compounds. Part I. Polymerization with vanadium pentoxide and metal vanadates (1969)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 124 (1969), S. 263-273 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In Gegenwart von Vanadiumpentoxid als heterogenern Katalysator Wurde N-Vinylcarbazol (NVC) in Substanz polymerisiert. Die Polymerisationsgeschwindigkeit hängt vom Verhältnis des Katalysators zum Monomeren ab. Es wurde ein kationischer Reaktionsmechanismus vorgeschlagen, und es wurde versucht, die Rolle der V2O5-Oberfläche bei der Polymerisation aufzuklären. Es wird vermutet, daß die π-Säureeigenschaft des V5⊕-Ions bei der Initiierung der Polymerisation miteinbezogen werden muß.Die Wirkung einer Anzahl von Zusätzen auf die Polymerisationsgeschwindigkeit wurde untersucht; das Ergebnis bekräftigt die Annahme eines kationischen Verlaufs.Es wurde auch die katalytische Wirksamkeit einer Anzahl von Metallvanadaten bei der Polymerisation von NVC untersucht. Es ergab sich eine hinreichend gute Bezichung zwischen der katalytischen Wirksamkeit und dem elektronegativen Charakter des metallischen Bestandteils.
    Notes: Bulk polymerization of N-Vinylcarbazole (NVC) has been carried out using vanadium pentoxide as the contact catalyst. The rate of polymerizatlon has been found to depend upon catalyst to monomer ratio. A cationic mechanism has been suggested and the role of V2O5 surface in the polymerization has been tentatively analyzed. The π-acid characteristies of V5⊕ ion is believed to be involved in initiating the polymerization. The effect of a number of additives on the polymerization rate has been studied, which endorses the cationic mechanism. The catalytic efficiency of a number of metal vanadates for the polymerization of NVC has also been studied. A fairly good correlation between the activity and electronegativity of the metallic moiety has been established.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1969.021240127
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  • 4
    Electronic Resource
    Electronic Resource
    Interaction of polylysine with phosvitin and nucleic acids (1969)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 124 (1969), S. 113-117 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die DNS-abhängige RNS-Synthese wird durch basische Proteine, wie Histone oder Polylysin, gehmmt: es wurde gefunden, daß dieser Hemmungseffekt durch Phosvitin, ein phosphoprotein, aufgehoben wird. Turbidimetrische Untersuchungen ergaben, daß Polylysin mit DNS iind RNS in stöchiometrischem Verhältnis reagiert.Es wird angenommen, daß diese Reaktion mit DNS die Ursache des Hemmungseffektes ist. Noch wirksamer als DNS reagiert Phosvitin mit Polylysin. Phosvitin kann in viel geringerer als der stöchiometrischen Menge mit DNS um Polylysin konkurrieren, also DNS freisetzen und als Matrize für die RNS-Synthese verfügbar machen. Phosphoserin ist, im Gegensatz zu Phosvitin, unwirksam bei der Aufhebung des Hemmungseffektes von Polylysin.
    Notes: DNA dependent RNA asynthesis in inhibited by basic proteins like histones or polylysine This inhibitory effect is found to be suppressed by phosvitin, which is a phosphoprotein. Turbidometric studies indicate that polylysine interacts with DNA and RNA stoichiometrically. This interaction with DNA has been thought to be the cause of this inhibitory effect. Phovitin also interacts with polylysine more effectively than DNA. Phosvitin in quantities much less than the stoichionietric amount can compete with DNA for the polylysine and can thus make DNA free and available as template for the RNA synthesis. Phosphoserine, unlike pbosvitin, is ineffective in suppressing the inhibitory effect of polylysine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1969.021240112
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  • 5
    Electronic Resource
    Electronic Resource
    Reno-flavin und Vitamin B2 (1935)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 68 (1935), S. 427-428 
    Details
    ISSN: 0365-9631
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19350680309
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  • 6
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    I/O Performance Characterization of Lustre and NASA Applications on Pleiades (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In this paper we study the performance of the Lustre file system using five scientific and engineering applications representative of NASA workload on large-scale supercomputing systems such as NASA s Pleiades. In order to facilitate the collection of Lustre performance metrics, we have developed a software tool that exports a wide variety of client and server-side metrics using SGI's Performance Co-Pilot (PCP), and generates a human readable report on key metrics at the end of a batch job. These performance metrics are (a) amount of data read and written, (b) number of files opened and closed, and (c) remote procedure call (RPC) size distribution (4 KB to 1024 KB, in powers of 2) for I/O operations. RPC size distribution measures the efficiency of the Lustre client and can pinpoint problems such as small write sizes, disk fragmentation, etc. These extracted statistics are useful in determining the I/O pattern of the application and can assist in identifying possible improvements for users applications. Information on the number of file operations enables a scientist to optimize the I/O performance of their applications. Amount of I/O data helps users choose the optimal stripe size and stripe count to enhance I/O performance. In this paper, we demonstrate the usefulness of this tool on Pleiades for five production quality NASA scientific and engineering applications. We compare the latency of read and write operations under Lustre to that with NFS by tracing system calls and signals. We also investigate the read and write policies and study the effect of page cache size on I/O operations. We examine the performance impact of Lustre stripe size and stripe count along with performance evaluation of file per process and single shared file accessed by all the processes for NASA workload using parameterized IOR benchmark.
    Keywords: Computer Systems
    Type: ARC-E-DAA-TN6025 , HiPC 2012; Dec 18, 2012 - Dec 21, 2012; Pune; India
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    An Application-Based Performance Evaluation of NASAs Nebula Cloud Computing Platform (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The high performance computing (HPC) community has shown tremendous interest in exploring cloud computing as it promises high potential. In this paper, we examine the feasibility, performance, and scalability of production quality scientific and engineering applications of interest to NASA on NASA's cloud computing platform, called Nebula, hosted at Ames Research Center. This work represents the comprehensive evaluation of Nebula using NUTTCP, HPCC, NPB, I/O, and MPI function benchmarks as well as four applications representative of the NASA HPC workload. Specifically, we compare Nebula performance on some of these benchmarks and applications to that of NASA s Pleiades supercomputer, a traditional HPC system. We also investigate the impact of virtIO and jumbo frames on interconnect performance. Overall results indicate that on Nebula (i) virtIO and jumbo frames improve network bandwidth by a factor of 5x, (ii) there is a significant virtualization layer overhead of about 10% to 25%, (iii) write performance is lower by a factor of 25x, (iv) latency for short MPI messages is very high, and (v) overall performance is 15% to 48% lower than that on Pleiades for NASA HPC applications. We also comment on the usability of the cloud platform.
    Keywords: Computer Systems
    Type: ARC-E-DAA-TN5169 , 14th IEEE International Conferenc eon HPCC-2012; Jun 25, 2012; Liverpool; United Kingdom
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    NASA TECHNICAL REPORTS
  • 8
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    A Look at the Impact of High-End Computing Technologies on NASA Missions (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: From its bold start nearly 30 years ago and continuing today, the NASA Advanced Supercomputing (NAS) facility at Ames Research Center has enabled remarkable breakthroughs in the space agency s science and engineering missions. Throughout this time, NAS experts have influenced the state-of-the-art in high-performance computing (HPC) and related technologies such as scientific visualization, system benchmarking, batch scheduling, and grid environments. We highlight the pioneering achievements and innovations originating from and made possible by NAS resources and know-how, from early supercomputing environment design and software development, to long-term simulation and analyses critical to design safe Space Shuttle operations and associated spinoff technologies, to the highly successful Kepler Mission s discovery of new planets now capturing the world s imagination.
    Keywords: Computer Systems
    Type: ARC-E-DAA-TN4714
    Format: application/pdf
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  • 9
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    Performance Analysis of Scientific and Engineering Applications Using MPInside and TAU (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In this paper, we present performance analysis of two NASA applications using performance tools like Tuning and Analysis Utilities (TAU) and SGI MPInside. MITgcmUV and OVERFLOW are two production-quality applications used extensively by scientists and engineers at NASA. MITgcmUV is a global ocean simulation model, developed by the Estimating the Circulation and Climate of the Ocean (ECCO) Consortium, for solving the fluid equations of motion using the hydrostatic approximation. OVERFLOW is a general-purpose Navier-Stokes solver for computational fluid dynamics (CFD) problems. Using these tools, we analyze the MPI functions (MPI_Sendrecv, MPI_Bcast, MPI_Reduce, MPI_Allreduce, MPI_Barrier, etc.) with respect to message size of each rank, time consumed by each function, and how ranks communicate. MPI communication is further analyzed by studying the performance of MPI functions used in these two applications as a function of message size and number of cores. Finally, we present the compute time, communication time, and I/O time as a function of the number of cores.
    Keywords: Computer Operations and Hardware
    Type: ARC-E-DAA-TN1911 , 12th IEEE HPCC conference; Sep 01, 2010 - Sep 03, 2010; Melbourne; Australia
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    NASA Advanced Computing Environment for Science and Engineering (2014)
    In:  CASI
    Details
    Publication Date: 2019-11-16
    Description: High-fidelity modeling, simulation, and analysis, enabled by supercomputing, are becoming increasingly important to NASAs broad spectrum of missions. This paper describes NASAs advanced supercomputing environment at Ames Research Center that is geared toward solving the space agencys most challenging science and engineering problems.
    Keywords: Computer Systems
    Type: ARC-E-DAA-TN15006 , International Conference on Parallel Computational Fluid Dynamics Parallel; May 20, 2014 - May 22, 2014; Trondheim; Norway
    Format: application/pdf
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