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  • 1
    Electronic Resource
    Electronic Resource
    Peroxidase and laccase as catalysts for removal of the phenylhydrazide protecting group under mild conditions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1137-1141 
    Details
    ISSN: 0006-3592
    Keywords: peroxidase ; laccase ; phenylhydrazide protecting group ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method is proposed for the removal of the phenylhydrazide protecting group by the action of peroxidase or laccase, the enzymes attributed to the class of oxidoreductases. The deblocking procedure is performed under mild oxidative conditions, i.e., aqueous solution and neutral or close to neutral pH. Such mild oxidizing agents as 1 mM H2O2 and air oxygen are used for unmasking. The method is available for the deblocking of both α- and γ-carboxyl groups. The enzyme-catalyzed removal of the phenylhydrazide protecting group causes no oxidative modification nor destruction of methionine or tryptophan side chains. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260421002
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  • 2
    Electronic Resource
    Electronic Resource
    The Use of Intermediates with Preformed Disulfide Bridge for the Synthesis of Oxytocin and Deamino-oxytocin (1972)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 55 (1972), S. 2854-2860 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The disulfide-bridged hexapeptides 6a and 6b have been prepared from benzyl-protected intermediates. Coupling of 6a and 6b with prolyl-leucyl-glycine amide afforded deamino-oxytocin (7a) and the protected oxytocin derivative 7b, respectively; the latter was converted to oxytocin (7c) by removal of the Boc protecting group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19720550817
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  • 3
    Electronic Resource
    Electronic Resource
    Untersuchungen zum System Te/O/Br (1978)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 439 (1978), S. 13-28 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the System Te/O/BrThe melting point diagram of the system TeBr4—TeO2 was obtained by total pressure measurements and DTA measurements. A Congruent melting composition Te6O11Br2 exists, the melting point is 570°C.The enthalpy of formation and the standard entropy of the species TeOBr2,g was derived from measurements of the total pressure over Te6O11Br2/TeBr4 and from the transport behaviour of the TeO2 with Br2.From the decomposition-pressure measurements over Te6O11Br2/TeO2 follow the partial pressure.The enthalpy of formation ΔH°(Te6O11Br2,f,298) = -453.5 kcal/Mol was obtained from the enthalpy of solution. The transport-behaviour of TeO2 with HBr, with Tebr4 and Br2 and that of Te6O11Br2 is clear with the thermodynamic data of TeObr2.
    Notes: Das Schmelzdiagramm des Systems TeO2—TeBr4 wurde durch Dampfdruckmessungen und DTA ermittelt. Im System existiert eine bei 570°C kongruent schmelzende Verbindung Te6O11Br2Aus Dampfdruckmessungen über Te6O11Br2/TeBr4 und Messung des Gesamtdruckes TeO2,f/Br2,g sowie der Auswertung des Transportverhaltens des TeO2 mit Br2 wurden die Bildungsenthalpie und die Standardentropie der Gasphasenspezies TeOBr2 abgeleitet. Aus den Zersetzungsdruckmessungen über Te6O11Br2/TeO2 folgen die Partialzersetzungsdrucke.Lösungscalorimetrisch wurde die Bildungsenthalpie ΔH0(Te6O11Br2,f,298) = -453,5 kcal/Mol ermittelt.Das Transportverhalten von TeO2 mit HBr, TeBr4 und Br2, sowie das des Te6O11Br2 ist mit den thermodynamischen Daten des TeOBr2 verständlich und beschreibbar.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19784390102
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  • 4
    Electronic Resource
    Electronic Resource
    Novel bis(napthalic anhydrides) and polyheteroarylenes on their basis (1988)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 460-464 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe neuer Bis(naphthalincarbonsäureanhydride) wurden durch Umsatz von Acenaphthen mit Dichloranhydriden von Dicarbonsäuren unter den Bedingungen einer Friedel-Crafts-Reaktion mit Chloral bzw. Bromal und nachfolgender Oxidation der Bis(acenaphthyle) und Anhydridisierung der Tetracarbonsäuren synthetisiert. Aus diesen Anhydriden und Bis(o-phenylendiaminen) erhaltene Poly(naphthoylen-benzoimidazole) vereinen gute thermische Eigenschaften mit Löslichkeit in organischen Lösungsmitteln.
    Notes: A series of novel bis(naphthalic anhydrides) has been prepared through acenapthene interaction with the dichloroanhydrides of dicarboxylic acids under the conditions of the Friedel-Crafts reaction or with chloral and bromal followed by oxidation of bis-acenaphthyls and anhydrization of the tetracarboxylic acids synthesized. Poly(naphthoylene benzoimidazoles) combining advantageous thermal properties and solubility in organic solvents have been obtained through interaction between the synthesized anhydrides and bis(o-phenylene diamines).
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1988.010390818
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  • 5
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    A Model for the Sources of the Slow Solar Wind (2010)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind has large angular width, up to approximately 60 degrees, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far front the heliospheric current sheet. We then use an MHD code and MIDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind and magnetic field for a time period preceding the August 1, 2008 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model.
    Keywords: Solar Physics
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  • 6
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    The Evolution of Open Magnetic Flux Driven by Photospheric Dynamics (2010)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The coronal magnetic field is of paramount importance in solar and heliospheric physics. Two profoundly different views of the coronal magnetic field have emerged. In quasi-steady models, the predominant source of open magnetic field is in coronal holes. In contrast, in the interchange model, the open magnetic flux is conserved, and the coronal magnetic field can only respond to the photospheric evolution via interchange reconnection. In this view the open magnetic flux diffuses through the closed, streamer belt fields, and substantial open flux is present in the streamer belt during solar minimum. However, Antiochos and co-workers, in the form of a conjecture, argued that truly isolated open flux cannot exist in a configuration with one heliospheric current sheet (HCS) - it will connect via narrow corridors to the polar coronal hole of the same polarity. This contradicts the requirements of the interchange model. We have performed an MHD simulation of the solar corona up to 20R solar to test both the interchange model and the Antiochos conjecture. We use a synoptic map for Carrington Rotation 1913 as the boundary condition for the model, with two small bipoles introduced into the region where a positive polarity extended coronal hole forms. We introduce flows at the photospheric boundary surface to see if open flux associated with the bipoles can be moved into the closed-field region. Interchange reconnection does occur in response to these motions. However, we find that the open magnetic flux cannot be simply injected into closed-field regions - the flux eventually closes down and disconnected flux is created. Flux either opens or closes, as required, to maintain topologically distinct open and closed field regions, with no indiscriminate mixing of the two. The early evolution conforms to the Antiochos conjecture in that a narrow corridor of open flux connects the portion of the coronal hole that is nearly detached by one of the bipoles. In the later evolution, a detached coronal hole forms, in apparent violation of the Antiochos conjecture. Further investigation reveals that this detached coronal hole is actually linked to the extended coronal hole by a separatrix footprint on the photosphere of zero width. Therefore, the essential idea of the conjecture is preserved, if we modify it to state that coronal holes in the same polarity region are always linked, either by finite width corridors or separatrix footprints. The implications of these results for interchange reconnection and the sources of the slow solar wind are briefly discussed.
    Keywords: Solar Physics
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  • 7
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    Magnetic Topology of Coronal Hole Linkages (2010)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: In recent work, Antiochos and coworkers argued that the boundary between the open and closed field regions on the Sun can be extremely complex with narrow corridors of open ux connecting seemingly disconnected coronal holes from the main polar holes, and that these corridors may be the sources of the slow solar wind. We examine, in detail, the topology of such magnetic configurations using an analytical source surface model that allows for analysis of the eld with arbitrary resolution. Our analysis reveals three important new results: First, a coronal hole boundary can join stably to the separatrix boundary of a parasitic polarity region. Second, a single parasitic polarity region can produce multiple null points in the corona and, more important, separator lines connecting these points. Such topologies are extremely favorable for magnetic reconnection, because it can now occur over the entire length of the separators rather than being con ned to a small region around the nulls. Finally, the coronal holes are not connected by an open- eld corridor of finite width, but instead are linked by a singular line that coincides with the separatrix footprint of the parasitic polarity. We investigate how the topological features described above evolve in response to motion of the parasitic polarity region. The implications of our results for the sources of the slow solar wind and for coronal and heliospheric observations are discussed.
    Keywords: Solar Physics
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  • 8
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    A Model fot the Sources of the Slow Solar Wind (2011)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Models for the origin of the slow solar wind must account for two seemingly contradictory observations: the slow wind has the composition of the closed-field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to approx.60deg, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind, and magnetic field for a time period preceding the 2008 August 1 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere and propose further tests of the model. Key words: solar wind - Sun: corona - Sun: magnetic topology
    Keywords: Solar Physics
    Type: The Astrophysical Journal; 731; 2
    Format: text
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  • 9
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    The Structure and Dynamics of the Corona - Heliosphere Connection (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Determining the source at the Sun of the slow solar wind is one of the major unsolved problems in solar and heliospheric physics. First, we review the existing theories for the slow wind and argue that they have difficulty accounting for both the observed composition of the wind and its large angular extent. A new theory in which the slow wind originates from the continuous opening and closing of narrow open field corridors, the S-Web model, is described. Support for the S-Web model is derived from MHD solutions for the quasisteady corona and wind during the time of the August 1, 2008 eclipse. Additionally, we perform fully dynamic numerical simulations of the corona and heliosphere in order to test the S-Web model as well as the interchange model proposed by Fisk and co-workers. We discuss the implications of our simulations for the competing theories and for understanding the corona - heliosphere connection, in general.
    Keywords: Solar Physics
    Type: GSFC.JA.00292.2012
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  • 10
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    Predicting the Structure of the Solar Corona for the Total Solar Eclipse of March 29,2006 (2007)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We describe the use of a three-dimensional MHD model to predict the s tructure of the corona prior to the total solar eclipse of March 29, 2006. The calculation uses the observed photospheric radial magnetic f ield as a boundary condition. We use a new version of our model that has an improved description of energy transport in the corona. The mo del allows us to predict the emission of X-ray and EUV radiation in t he corona. We compare the predicted polarization brightness in the co rona with four observations of the eclipse from Greece, Egypt, and Li bya, and we demonstrate that the model accurately predicts the largescale structure of the corona. We also compare X-ray emission from the model with GOES/SXI images.
    Keywords: Solar Physics
    Type: Solar and Stellar Physics Through Eclipses. ASP Conference Series; 370; 299-307
    Format: text
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