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  • Polymer and Materials Science  (12)
  • enthalpy of dissolution  (3)
  • Exocrine pancreas  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Investigation of salt — Mixed solvent systems. XXXVII. Crystallization enthalpy of lithium chloride in mixed solvent systems (1990)
    Springer
    Journal of solution chemistry 19 (1990), S. 437-446 
    Details
    ISSN: 1572-8927
    Keywords: Acetone ; enthalpy of crystallization ; enthalpy of dissolution ; enthalpy of transition ; ion-solvent interaction ; lithium chloride ; methanol ; N,N-dimethylformamide ; solvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystallization enthalpy of LiCl at 25°C in LiCl-H2O-cosolvent systems is determined calorimetrically as a function of the cosolvent content in the mixed solvent. This parameter is used for the investigation of heat phenomena accompanying the solvation of the salt in a saturated solution. The cosolvents employed include methanol, acetone, and N,N-dimethylformamide. The most pronounced change is effected by replacement of water with N,N-dimethylformamide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650376
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  • 2
    Electronic Resource
    Electronic Resource
    Investigations of salt — Mixed solvent systems XXXVIII. Crystallization enthalpy of magnesium chloride in mixed solvent systems (1990)
    Springer
    Journal of solution chemistry 19 (1990), S. 447-455 
    Details
    ISSN: 1572-8927
    Keywords: Acetone ; enthalpy of crystallization ; enthalpy of dissolution ; enthalpy of transition ; ion-solvent interaction ; magnesium chloride ; methanol ; N,N-dimethylformamide ; solvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystallization enthalpies of MgCl2 in MgCl2−H2O-cosolvent systems at 25°C were determined calorimetrically as a function of the cosolvent content in the mixed solvent. Methanol, acetone, and N,N-dimethylformamide were employed as cosolvents. The results show the individual cosolvents to have very differently influences on the energy state of the salt in the saturated solution. The most pronounced changes are effected by an increase of the DMF content in the mixed solvent. The intensity of Mg2+-DMF interaction at a higher DMF content in the saturated solution considerably exceeds the Li+-DMF interaction in LiCl solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650377
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  • 3
    Electronic Resource
    Electronic Resource
    Enthalpy of crystallization of lithium chloride from aqueous solution at 25°C (1986)
    Springer
    Journal of solution chemistry 15 (1986), S. 269-282 
    Details
    ISSN: 1572-8927
    Keywords: Activity coefficients ; enthalpy of crystallization ; enthalpy of dissolution ; enthalpy of formation ; lithium chloride ; solubility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The enthalpies of crystallization of LiCl and LiCl·H2O from aqueous solutions at 25°C are reported as measured by a calorimetric method and derived from the previously published concentration dependence of the enthalpy of solution data. The results are compared with those obtained from the concentration dependence of activity coefficients and from the temperature dependence of solubilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00646695
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  • 4
    Electronic Resource
    Electronic Resource
    Exocrine pancreas under experimental conditions (1976)
    Springer
    Cell & tissue research 171 (1976), S. 467-482 
    Details
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Secretion process ; Protein synthesis ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary After the application of parachlorophenylalanine (pCPA), an amino acid analogue, paracrystalline inclusions are observed in the exocrine pancreas of the rat. The formation of the paracrystalline structures varies according to the dose and the time of examination. Although the first alterations can be seen in the Golgi apparatus and the condensing vacuoles, the main localization of these structures is within the cisternae of the RER. At the same time as degenerative changes occur in the cells, involving autophagic and heterophagic processes, regneration also takes place. With the freeze-fracturing method, the paracrystalline inclusions are interpreted as lamellae or plates of probably altered secretory proteins in extremely extended RER-cisternae. The fracture surfaces of the paracrystals show a periodicity of about 80 Å running diagonally to the main axis of the paracrystalline structures, which are mainly oriented from the basal parts of the exocrine pancreatic cells to the cell apices. The mechanism of paracrystalline formation is discussed on the basis of the morphologic results. It could be shown that after pCPA administration the amylase content is decreased concomittantly with degranulation. pCPA seems not to be incorporated into secretory proteins; high intracellular concentrations, however, are required to induce the formation of the paracrystalline structures. This morphological study is the basis for other studies dealing with secretion and intracellular transport in the pancreatic acinar cell under experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220239
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  • 5
    Electronic Resource
    Electronic Resource
    Exocrine pancreas under experimental conditions (1977)
    Springer
    Cell & tissue research 177 (1977), S. 459-474 
    Details
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Isolated cells ; Cell membrane ; Tight junctions ; Gap junctions ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the cell membrane and intercellular junctions was studied after isolation of exocrine pancreatic cells by tryptic digestion and mechanical treatment. The number and distribution of membrane associated particles does not change significantly when acinar cells in situ are compared to those after the isolation procedure. However, intercellular junctions undergo distinct alterations. Gap junctions in normal pancreatic cells are macular in shape and localized at the lateral parts of the cell membrane. In isolated acinar cells gap junctions are irregularly shaped, more extended, and frequently associated with tight junctions. Tight junctions form belt-like structures which are found to persist after isolation but subsequently become elongated and interrupted. Thus extensive macular areas of tight junctions develop. Further, the strands on the P-face and the grooves on the E-face of freeze-fracture replicas change in array, dissociate, and become loosely packed on large membrane areas. The present investigation shows that the intramembranous proteins of tight and gap junctions are mobile structures within the fluid membrane. The shape of their array is dependent on the form of the intercellular contact zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220607
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  • 6
    Electronic Resource
    Electronic Resource
    Maßgeschneiderte Schicht-Interfacesysteme mittels ionenstrahlgestützter Beschichtung (1998)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 518-524 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Custom-Tailored Coating-Interface Systems by Means of lon Beam Assisted DepositionA coated sample represents in its most simple form a threefold junction consisting of substrate interface and top layer. In many cases the top layer consists again of several sublayers or the interface contains a modified substrate surface and an interconnection between top layer and interface. An ideal coating technique is evaporation under simultaneous ion bombardment with an ion source it is possible because of several free parameters to come close to an ideal system.For the coating Al/Al2O3 on steel it is shown that the width of a composition gradient between the sublayers Al and Al2O3 can be optimized with respect to excellent corrosion resistance.The example CrxN coating on steel or corrosion and wear resistence demonstrate the ability to optimize the corrosion and wear resistence by modifying the microstructure via variation of the parameters ion energy, ion impact angle, ion to atom ratio and process temperature.Finally, TiN layers on steel were chosen to show that the ion beam parameters influence the porosity and the crystal structure of the coatings. This fact can be used to optimize the corrosion protection or wear reduction obtained by the coating. Especially the multilayer Ti/TiO2/TiN exhibits very interesting properties.
    Notes: Ein beschichtetes Bauteil stellt in seiner einfachsten Form einen Dreierverbund aus Substrat, Interface und Schicht dar, in vielen Fällen kann die Schicht aus mehreren Untersystemen bzw. das Interface aus der modifizierten Substatrandschicht und einem Zwischenbereich zur Schicht bestehen. Eine ideale Beschichtungsmethode sollte es daher erlauben, alle diese Schichten bzw. Schichtbereiche in kontrollierter und aufeinander abgestimmter Form zu erzeugen.Mittels des IBAd-Verfahrens, bei dem Aufdampfschichten während ihrer Abscheidung mit Ionen aus einer Ionenquelle beschossen werden, ist es möglich, infolge der zahlreichen frei wählbaren Parameter sich an das ideale System heranzutasten.Anhand des Verbunds Stahl/Al/Al2O3 wird erlätert, wie durch einen in der Ausdehnung optimierten Zusammensetzungsgradienten das Interface zwischen den Subschichten Al und Al2O3 bezüglich des Korrosionsschutzvermögens der Schicht verbessert werden kann.An CrxN-Schichten wird demonstriert, daß durch die Wahl der Parameter Ionenenergie, Ioneneinfallswinkel, Ionen/Atom-Verhältnis und Prozeßtemperatur über die Mikrostruktur von Schicht und Oberfläche das Verschleiß-und Korrosionsverhalten sowie die Härte angepaßt werden können.Am Beispiel TIN auf Stahl zeigt sich, daß je nach Ionenstrahlparameter die Porosität und damit das Korrosionsverhalten bzw. die Kristallinität und damit Härte und Verschleißverhalten optimiert werden können. Besonders Mehrlagenschichten Ti/TiO2/TiN zeigen interessante Eigenschaften.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19980290910
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  • 7
    Electronic Resource
    Electronic Resource
    Verschleißminderung an hartverchromten Kolbenringen durch Ionenimplantation (1987)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 18 (1987), S. 356-359 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19870181013
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  • 8
    Electronic Resource
    Electronic Resource
    Ionen- und plasmagestützte Verfahren der Oberflächentechnik für die Randschichtbehandlung von Leichtmetallwerkstoffen (1998)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 537-544 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Surface engineering of light weight materials with ion- and plasma-assisted methodsIncreasing applications of light weight materials are expected in the future. Pursuing this trend surface engineering of these materials - especially ion- and plasma-assisted methods - swill be of increasing interest to enhance their wear and corrosion resistance. In a research co-operation some promising methods were examined on different aluminium and titanium alloys to assess their potential to increase the surface properties. Among these were magnetron sputtering of chromium nitride, ion beam assisted deposition of Cr/CrN and Al/A2O3 layers, ion implantation and ion beam assisted nitriding. Compared to the steel substrates the assessment of the mechanical properties such as the critical load of the scratch test of the coated light weight materials is different. Furthermore, it could be shown that both spherical section and glow discharge optical spectroscopy are useful methods to characterize the near-surface zone influenced by ion implantation.
    Notes: Es ist zu erwarten, daß die Anwendungsbreite von Leichtmetall-legierungen in Zukunft noch steigen wird. Mit diesem Trend werden auch oberflächentechnische Methoden - insbesondere ionen- und plasmaunterstützte Verfahren - gefragt sein, um den Verschleiß- und Korrosionswiderstand der Oberflächen zu verbessern. Im Rahmen eines Verbundprojektes wurden verschiedene aussichtsreiche Verfahren untersucht, um ihr Potential zur Verbesserung der Oberflächeneigenschaften von Aluminium- und Titanlegierungen einschätzen zu können. Hierunter befanden sich das Magnetronsputtern von Chromnitrid, die ionenstrahluntersützte Abscheidung von Cr/CrN- und Al/A2O3Schichten, die Ionenimplantation und das Ionenstrahlnitrieren. Im Vergleich mit beschichteten Stahlsubstraten ergeben sich Unterschiede bei der Einschätzung wichtiger mechanischer Eigenschaften, wie der im Ritztest ermittelten kritischen Last. Weiterhin konnte gezeigt werden daß sowohl der Kalottenschliff als auch die Glimmentladungspektroskopie gut geeignet sind, die durch Ionenimplantation beeinflußte Randzone zu charakterisieren.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19980290912
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  • 9
    Electronic Resource
    Electronic Resource
    Erzeugung verschleißmindernder Randschichten durch Ionenstrahlverfahren (1993)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 24 (1993), S. 109-119 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Formation of Wear Resistant Surface Layers by Ion Beam TechniquesIon beam techniques are state of the art procedures for the microelectronic industries. Recently they found more and more interest in materials science with respect to surface improvement of polymers, ceramics and metals.In this contribution at first the procedures and the equipment for ion implantation and ion beam assisted deposition are described.Then examples for basic investigations concerning the formation of hard, dense and non-porous surface coatings with potential for wear and corrosion inhibition are given. Especially the interdependency of ion beam parameters, microstructure of coating and interface and macroscopic properties of the coating/substrate system are discussed. Finally the surface treatment of piston seals, ball bearings and metal forming tools is mentioned illustrating the application potential of ion beam techniques.
    Notes: Die in der Mikroelektronik industriell angewandten Ionenstrahlverfahren finden mehr und mehr Eingang in die Materialforschung zur Oberflächenvergütung von Polymeren, Keramiken und Metallen. In diesem Beitrag werden zunächst die Ionenimplantation und die ionenstrahlgestützte Beschichtung (IBAD) methodisch und apparativ beschrieben. Sodann werden Beispiele für Grundlagenuntersuehungen zur Erzeugung harter, dichter, verschleiß- und korrosionsmindernder Randschichten erwähnt. Dabei wird besonders anf die Zusammenhänge zwischen Ionenstrahlparametern, Mikrostruktur der Schicht bzw. Grenzzone Schicht/Substrat und mechanischen und chemischen makroskopischen Systemeigenschaften eingegangen. Schließlich werden am Beispiel von Kolbenringen, Umformwerkzeugen und Wälzlagern Anwendungspotentiale der Verfahren erläutert.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19930240309
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  • 10
    Electronic Resource
    Electronic Resource
    Electrochemical evaluation of thin films and coatings deposited with ion beam assisted deposition (IBAD) using scanning electrochemical microelectrode (1998)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 66-71 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Elektrochemische Untersuchungen an mittels ionenstrahlunterstützter Beschichtung (IBAD) abgeschiedenen Schichten mit der „Scanning-Electro-chemical-Microelectrode“In diesem Beitrag wird die Anwendung einer neueren elektrochemischen Methode, der Scanning-Electrochemical Microelectrode (SEME), am Beispiel der Charakterisierung dünner ionenstrahlunterstützter Beschichtungen (IBAD) vorgestellt. Der Trend bei der Entwicklung korrosionschützender dünner Beschichtungen führt zu kombinierten Mehrfach-Schichtsystemen, die bei geringerer Schichtdicke technisch etablierte Verfahren ersetzen Könnten. Aufgrund der geringen Schichtdicke können Verunreinigungen oder Schichtfehler das Korrosionsschutzvermögen erheblich beeinflussen. Die SEME, für die eine Anlage aufgebaut wurde, steht eine geeignete Methode zur Detektion dieser Schichtfehler dar. Die Funktionsweise beruht im wesentlichen auf Potential- und Stromdichte-Messungen, wobei wegen der lateralen Auflösung von ca. 20 μm Potentiale bzw. Stromdichten lokal gemessen werden können. 2-dimensionale Scans führen zu einem elektrochemischen Abbild der Oberfläche. Die Leistungsfähigkeit dieser Methode wird im vorliegenden Artikel am Beispiel von Al/Al2O3 Schichtsystemen auf CK45 demonstriert, wobei die großflächige und lokale elektrochemische Information verglichen werden.
    Notes: In this contribution the application of a modern technique-scanning electrochemical microelectrode - for the evaluation of thin films which were deposited (IBAD) is illustrated. New tendencies in the development of thin films with anticorrosive purpose lead to the development of multi-layer systems acting similar to those commonly, applied in the industry, however, being much thinner. Imperfections and defects are commonly introduced in the coating during the deposition process, and these affect the anticorrosive properties of the film. In order to make a local electrochemical study of these multi-layer systems we have developed equipment in order to perform electrochemical surface-scans (potential and current density) on the basis of a microelectrode with a good lateral resolution (approximately 20 μm). Al-Al2O3 multilayers on steel substrates with differently designed interfaces were investigated to show the variation of uniform and local electrochemical information obtained in dependence on the coating deposition parameters.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19980290209
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