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  • Polymer and Materials Science  (11)
  • Cell & Developmental Biology  (3)
  • Nucleosides  (3)
  • 1
    Electronic Resource
    Electronic Resource
    ESCA analysis of partially converted lignocellulosic materials (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 1909-1919 
    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: Further ESCA data of the solid residues obtained by supercritical extraction of Populus tremuloides are reported. The changes of the ESCA spectra with the severity of grinding are discussed. These data allow us to draw precise conclusions on the spatial distribution of carbonaceous recondensed material as thermal conversion proceeds. The C1s peaks are of special interest as the distribution of the four components in these peaks bears information on the nature of the chemical compounds present on the surface of the sample.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350716
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and antiviral evaluation of quinazoline, thieno-[2,3-d]pyrimidine, and lumazine analogues of 3′-fluoro-3′-deoxythymidine (FLT) (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1371-1375 
    Details
    ISSN: 0947-3440
    Keywords: Nucleosides ; HIV ; 3′-Fluoronucleosides ; FLT analogues ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4(1H,3H)-Quinazolinediones 3a-c, lumazine (3d) and thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione (8) were silylated and condensed with methyl 2,3-dideoxy-3-fluoro-5-O-(4-phenylbenzoyl)-β-D-erythro-pentofuranoside (2) by using trimethylsilyl triflate as a catalyst to afford the corresponding cyclic nucleosides 4 and 9 and acyclic nucleosides 5 and 10. Removal of the protecting group from the glycon moiety was achieved in good yields by treatment with sodium methoxide in methanol at room temperature. The new FLT analogues were devoid of activity against HIV-1 and HSV-1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199507183
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of surfactants on the corrosion of amorphous 76Ni-24P alloy in neutral solutions (1994)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 45 (1994), S. 242-248 
    Details
    ISSN: 0947-5117
    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: Einfluß von oberflächenaktiven Stoffen auf die Korrosion der amorphen Legierung 76Ni-24P in neutralen LösungenDie Legierung 76Ni-24P- wurde elektrolytisch aus Lösungen abgeschieden, die zur, Verbesserung der Oberflächenqualität Natriumlaurylsulfat (SLS) und Triton-X 100 (TX-100) enthielten. Das Korrosionsverhalten dieser amorphen Legierungen wurde in Sulfat- und Chloridlösungenbei 25°C untersucht, und zwar mittels Potential-Zeit-Verhalten, linearem Polarisationswiderstand und potentiodynamischen Methoden. Die anodischen Polarisationskurven zeigen, daß die Legierung bei Potentialen zwischen etwa -200 und 200 mV (SCE) eine gewisse Passivität erreicht und oberhalb 200 mV (SCE) transpassiv in Lösung geht. In der Sulfatlösung ist die Auflösung der NiP-Legierung verstärkt, bei deren Abscheidung auf Messing oberflächenaktive Stoffe anwesend waren. Nichtanionische oberflächenaktive Stoffe erhöhen dabei den Korrosionsstrom um den Faktor 10, anionische hingegen um den Faktor 400. Zur Erklärung wird angenommen, daß in der Sulfatlösung bevorzugt die Mikrokristalle gelöst werden; eine Rolle spielt auch die sterische Behinderung der oberflächenaktiven Stoffe. In Chloridlösung sind die Legierungen bestandiger, da dann ein Phosphat/Hypophosphit-Film entsteht, der die Auflösung der Oberfläche verhindert.
    Notes: 76Ni-24P amorphous alloys have been electrodeposited from solutions containing sodium lauryl sulphate (SLS) and triton-X 100 (TX-100) to improve the surface quality of the specimens. Corrosion behaviour of electrodeposited amorphous alloys in sulphate and chloride solutions at 25°C has been studied by potential-time decay, linear polarization resistance and potentiodynamic techniques. Anodic polarization curves show that the specimens exhibit mild passivity at potentials between approximately -200 mV and 200 mV (SCE) and dissolve transpassively above 200 mV (SCE). The sulphate solution was found to increase the dissolution of the samples treated by the surfactants during the substrate brass plating. The nonanionic surfactant increases the corrosion current by 10 times compared to the anionic one which enhances the current by 400 times; the interpretation was based on the enhanced dissolution of the microcrystals of the specimens in the sulphate solution and to the steric hindrance of the surfactants. In addition, the alloys are more resistant to chlorides due to the formation of a phosphate/hypophosphite film which protects the surface from dissolution.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19940450405
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of surfactants on the Corrosion of amorphous 76Ni-24P alloy in neutral solutions (1993)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 44 (1993), S. 461-466 
    Details
    ISSN: 0947-5117
    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: Einfluß von oberflächenaktiven Stoffen auf die Korrosion der amorphen Legierung 76Ni-24P in neutralen LösungenDie Legierung 76Ni-24P wurde elektrolytisch aus Lösungen abgeschieden, die zur Verbesserung der Oberflächenqualität Natriumlaurylsulfat (SLS) und Triton-X 100 (TX-100) enthielten. Das Korrosionsverhalten dieser amorphen Legierungen wurde in Sulfat- und Chloridlösungen bei 25°C untersucht, und zwar mittels Potential-Zeit-Verhalten, linearem Polarisationswiderstand und potentiodynamischen Methoden. Die anodischen Polarisationskurven zeigen, daß die Legierung bei Potentialen zwischen etwa -200 und 200 mV (SCE) eine gewisse Passivität erreicht und oberhalb 200 mV (SCE) transpassiv in Lösung geht. In der Sulfatlösung ist die Auflösung der NiP-Legierung verstärkt, bei deren Abscheidung auf Messing oberflächenaktive Stoffe anwesend waren. Nichtanionische oberflächenaktive Stoffe erhöhen dabei den Korrosionsstrom um den Faktor 10, anionische hingegen um den Faktor 400. Zur Erklärung wird angenommen, daß in der Sulfatlösung bevorzugt die Mikrokristalle gelöst werden; eine Rolle spielt auch die sterische Behinderung der oberflächenaktiven Stoffe. In Chloridlösung sind die Legierungen beständiger, da dann ein Phosphat/Hypophosphit-Film entsteht, der die Auflösung der Oberfläche verhindert.
    Notes: 76Ni-24P amorphous alloys have been electrodeposited from solutions containing sodium lauryl sulphate (SLS) and triton-X 100 (TX-100) to improve the surface quality of the specimens. Corrosion behaviour of electrodeposited amorphous alloys in sulphate and chloride solutions at 25°C has been studied by potential-time decay, linear polarization resistance and potentiodynamic techniques. Anodic polarization curves show that the specimens exhibit mild passivity at potentials between approximately -200 mV and 200 mV (SCE) and dissolve transpassively above 200 mV (SCE). The sulphate solution was found to increase the dissolution of the samples treated by the surfactants during the substrate brass plating. The nonanionic surfactant increases the corrosion current by 10 times compared to the anionic one which enhances the current by 400 times; the interpretation was based on the enhanced dissolution of the microcrystals of the specimens in the sulphate solution and to the steric hindrance of the surfactants. In addition, the alloys are more resistant to chlorides due to the formation of a phosphate/hypophosphite film which protects the surface from dissolution.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19930441106
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  • 5
    Electronic Resource
    Electronic Resource
    Isolated pancreatic islets of the rat: An immunohistochemical and morphometric study (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 237 (1993), S. 489-497 
    Details
    ISSN: 0003-276X
    Keywords: Immunohistochemistry ; Isolated islets ; Morphometry ; Pancreas ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Although there is a recent increase in the use of the isolated pancreatic islets of the rat in the transplantation and functional studies, there has been no detailed quantitative assessment on the size and cellular constituents of islets after the isolation procedure. The present work was undertaken to study the size classes of the isolated islets and the morphometry of their cellular populations.Islets of the rat pancreas were isolated by using the intraductal collagenase digestion technique, the most commonly used procedure for the isolation of pancreatic islets. Different endocrine cells of the isolated islets were stained by immunoperoxidase staining techniques. The distribution of the cellular constituents of the isolated islets was similar to that of the intact islets of the normal pancreas; A, D, and PP cells were peripherally arranged around the centrally located B cells. However, morphometric quantitative study showed that the percent volume and percent number of A, D, and PP cells of the isolated islets were lower than those of the corresponding intact ones. Further, the mean true diameter of the isolated islets was lower than that of the intact ones. These data indicate loss of islet cells during the process of isolation. Most of the lost cells were from the periphery of islets. This may provide an explanation for the incomplete metabolic control and recurrence of hyperglycemia encountered after isolated islet transplantation in the treatment of diabetes mellitus. It seems that further refinements of the isolation techniques are necessary to obtain islet tissue with total cellular integrity, before a complete success in transplantation could be achieved. © 1993 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092370408
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  • 6
    Electronic Resource
    Electronic Resource
    ESCA study of the solid residues of supercritical extraction of Populus tremuloïdes in methanol (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 359-375 
    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: A systematic ESCA study of the solid residues of supercritical critical extraction of Populus tremuloïdes prepared in various conditions has been performed. Reference materials also examined by ESCA included the initial wood, Whatman no. 1 paper, and two lignins prepared by different procedures. Interest has been focused on the Cls and Ols spectra and on the determination of surface O/C atomic ratio. A difference between bulk O/C values measured by chemical analysis and surface O/C ratios obtained from ESCA data is considered diagnostic of a difference in chemical composition of the bulk and the surface. In the Cls peaks of wood and its constitutive polymers, the usual components peaks C1, C2, and C3 were observed. For the solid residues, however, a fourth peak designated as C0 appears, the importance of which increases steadily when the temperature of extraction is raised from 250 to 350°C. The component C0 was ascribed to polyaromatic constituants. Its proportion is correlated with the fraction of the carbon in the residue comprised in the recondensed material and determined independently. The Ols peak shows also a complex structure with three components in the wood-derived reference materials and four in some of the solid residues. These structures have not been discussed previously in the literature and a tentative assignment for the component peaks is proposed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340129
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  • 7
    Electronic Resource
    Electronic Resource
    Literature Survey on Solubility Data of Hydrogen in Liquid Solvents (1992)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 750-751 
    Details
    ISSN: 0009-286X
    Keywords: Data ; Solubility ; Hydrogen ; Solvents ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330640824
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  • 8
    Electronic Resource
    Electronic Resource
    Thin film PMMA precoating for improved implant bone-cement fixation (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 679-704 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: It has been argued that various specific requirements based on known principles of good adhesion are not being met in the current procedures of formation of the implant-bone cement interface. It has been shown that an annealed thin film PMMA precoating, applied in a low-contact-angle form to surgical alloy surfaces devoid of weak boundary layers, satisfies the majority of the requirements during interface formation. Techniques for the application of the precoating have been developed for SS316LVM, Co-Cr-Mo, and Ti-6Al-4V based on fracture toughness and fatigue tests, and fractography of the interface. Implant surface preparation methods have been established to yield surfaces amenable to adhesive bonding. The composition of the coatings have been studied from the point of view of implant surface wetting, coating roughness and thickness, and interface strength. A biocompatible silane coupling agent (A-174), currently used in orthodontics, has been introduced to provide saline resistant interfaces. The final precoated metal-bone cement interfaces have demonstrated fracture toughnesses in excess of that of bone cement even after prolonged exposure to 37°C physiological saline. Fatigue tests have shown that the fatigue lives (6.5 MPa) of the precoated metal interfaces in saline are at least twice, and in one case several orders of magnitude greater than, that of the uncoated ones even when the latter are tested dry. Fractography of the interfaces show failures that are entirely cohesive in nature. For the UHMWPE (ultrahigh molecular weight polyethylene)-bone cement interface, similar improvement with precoating, however, could not be attained. Finally, the coated metal-bone cement interfaces have been tested as a function of some clinical variables such as cement type, joining time, clinical contamination, and sterilization procedure. Results show that coated metals exhibit a certain level of insensitivity to these variables and retain their performance under all conditions except after particular repeated sterilizations.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160515
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of a cement-bone composite layer and prosthesis geometry on stresses in a prosthetically resurfaced tibia (1982)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 16 (1982), S. 929-949 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A comparative study of stress distributions in the component materials of a number of models of a prosthetically resurfaced tibia is presented. Although the geometry is idealized to be axisymmetric, the loadings for which the finite element analyses are performed are considered to be nonaxisymmetric, simulating more realistically the loading conditions in vivo. The different models are chosen with the view of determining the influence of changes in the prosthesis design on the induced stress distribution in the component materials. The changes considered are in the thickness of the cement and the cement-bone composite layers, and in the shape of the prosthesis. Experimentally measured values of strains are compared with the analytically predicted values to check the validity of the assumptions used in the finite element modeling. The comparison of induced stresses in the different materials reveals the desirability, from a mechanical behavior point of view, of introducing a cement-bone composite layer and using a prosthesis with domed subsurface in the fixation system. It is shown that for a model incorporating these features, considerable reduction of stresses in the cement, in its bulk and at its interface with the prosthesis plate, is achieved. The reduced stresses can be expected to have beneficial effects on the long-term behavior of the cement and its interfaces in the fixation system.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820160616
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  • 10
    Electronic Resource
    Electronic Resource
    The quasistatic and fatigue performance of the implant/bone-cement interface (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 15 (1981), S. 159-182 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Loosening is a major cause of failure in total arthroplasties. The efficacy of the fixation systems depends not only on the bulk properties of the components but also on the interfaces through which they interact. This study was initiated to examine the implant/bone-cement interface for four of the most commonly used implant materials, Co—Cr—Mo, Ti—6Al-4V, 316SSLVM and ultrahigh molecular weight polyethylene (UHMWPE). The surface preparation, specimen design, joining, and testing techniques were studied and then standardized in a manner which accurately represents current clinical procedures. The interfaces were tested for both their quasistatic and fatigue properties. Finite-element and fracture toughness analyses of the quasistatic shear specimens were performed in order to provide results of an absolute nature which could be subsequently compared to bulk material properties of bone cement. The interfaces were tested “dry” (i.e., at room temperature and 50% R.H.) and in physiological saline at 37°C. The interfaces demonstrated both fracture toughness and fatigue properties far inferior to those of bone cement. A predominantly interfacial type failure was observed using SEM fractography. The ultimate compressive strength (U.C.S.) of bone cement was measured after prolonged exposure to saline at 37°C and showed no decrease in U.C.S. suggesting that the reasons for the interface strength reductions were interfacial rather than bulk in nature. The “wetting'” ability of bone cement was measured using contact angles at various cure times on the four implant materials. These measurements showed that intimate interfacial contact is impossible with current clinical methods. This study indicates that failure of the implant/bonecement interface is likely only a short period after implantation and therefore may be a major contributor to implant loosening.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820150205
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