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  • Life and Medical Sciences  (7)
  • Polymer and Materials Science  (6)
  • Astrophysics
  • 1990-1994  (13)
  • 1
    Electronic Resource
    Electronic Resource
    Improved fire safety of composites for naval applications (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 16 (1992), S. 119-125 
    Details
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This study is based on the use of integral, hybrid thermal barrier to protect the core of the composite structure. Thermal barrier treatments evaluated in this study include ceramic fabric, ceramic coating, intumescent coating, hybrid of ceramic and intumescent coating, silicone foam, and phenolic skin. The composite systems evaluated in combination with thermal barrier treatments included glass/vinyl ester, graphite/epoxy, graphite/bismaleimide, and graphite/phenolic. All configurations were tested for flammability characteristics. These included smoke density and combustion gas generation (ASTM E-662), residual flexural strength (ASTM D-790), heat release rate, and ignitability (ASTM E-1354). ASTM E-662 test method covers the determination of specific optical density of smoke generated by solid materials. ASTM D-790 test method covers the determination of flexural properties of composite materials in the form of rectangular bars. ASTM E-1354 (cone calorimeter) covers the measurement of the response of materials exposed to controlled levels of radiant heating with or without an external ignitor, and is used to determine the ignitability, heat release rates, mass loss rates, effective heat of combustion, and visible smoke development. Without any fire barrier treatments, all composite systems evaluated in this study failed to meet ignitability and peak heat release requirements of MIL-STD-2031 (SH) at radiant heat fluxes of 75 and 100 kW m-2, respectively. Intumescent coating and a hybrid system consisting of intumescent coating over ceramic coating were the most effective fire barrier treatments for composite systems evaluated in this study. Using either of these treatments, all composite systems met the ignitability requirements of 90 and 60 at 75 and 100 kW m-2, respectively. Except for glass/vinyl ester, all systems also met the peak and average heat release requirements of MIL-STD-2031 (SH) at radiant heat fluxes of 25, 75, and 100 kW m-2, respectively.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fam.810160303
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of oligocyclosiloxanes via the hydrosilation of vinylsilanes and vinylsiloxanes with heptamethylcyclotetrasiloxane (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 891-900 
    Details
    ISSN: 0887-624X
    Keywords: oligocyclosiloxanes ; hydrosilation ; heptamethylcyclotetrasiloxane ; siloxane redistribution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of oligocyclosiloxanes via hydrosilation reactions has been investigated. Hydrosilation reactions employing heptamethylcyclotetrasiloxane and vinyl-containing silanes and siloxanes yielded a variety of oligocyclosiloxanes with various numbers of cyclosiloxane rings connected through tri-, tetra-, penta-, hexa-, hepta-, or octafunctional junctions. The oligocyclosiloxanes were characterized by gas chromatography, IR spectroscopy, 29Si-, 1H-, and 13C-NMR spectroscopy, elemental analysis, and vapor phase osmometry. The polycyclics were redistributed with hexamethyldisiloxane and the resulting fragments analyzed by gas chromatography. All results were consistent with the formation of isomeric oligocyclosiloxanes due to a lack of absolute regioselectivity of the hydrosilation reaction. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310407
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  • 3
    Electronic Resource
    Electronic Resource
    Torsional properties of healed canine diaphyseal defects grafted with a fibrillar collagen and hydroxyapatite/tricalcium phosphate composite (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 277-283 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The need for alternatives to autogenous bone grafts is widely recognized. This study compared the torsional strength of canine femora 1 year after grafting with one of three forms of a collagen/hydroxyapatite/tricalcium phosphate bone grafting material (COLLAGRAFT15), autogenous bone, or no graft. The groups were compared to each other and to the unoperated contralateral femora. Results of torsional testing were evaluated for torsional strength, torsional displacement, total energy to fracture and White fracture mode. Data analysis showed lower torsional strength of the operated vs. unoperated femora with the exception of morsellized COLLAGRAFT15 material, which had higher strength. However, the only difference in the operated groups was that the morsellized COLLAGRAFT15 had greater strength than several groups including the autogenous bone group. There was no difference found in angular displacement between any of the groups. However, there was a difference in the energy to fracture in both strip forms of the COLLAGRAFT15. The final conclusion is that in this model, grafting with COLLAGRAFT15 provided torsional properties at one year postoperatively at least equivalent to autogenous bone. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770050402
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  • 4
    Electronic Resource
    Electronic Resource
    Growth and protein phosphorylation in the Nb2 lymphoma: Effect of prolactin, cAMP, and agents that activate adenylate cyclase (1990)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 43 (1990), S. 327-337 
    Details
    ISSN: 0730-2312
    Keywords: forskolin ; cholera toxin ; pertussis toxin ; interleukin-2 ; T lymphocyte ; G protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The Nb2 T lymphoma is unique in that these lymphocytes proliferate in response to prolactin as well as in response to interleukin-2. In this study, we have examined the responsiveness of the adenylate cyclase system in Nb2 cells and the role of this signaling system in regulating proliferation and protein phosphorylation. An analog of cAMP inhibited prolactin-stimulated proliferation and blocked a prolactin-induced decrease in protein phosphorylation. Forskolin, a potent activator of adenylate cyclase in T lymphocytes, did not elevate cAMP levels in Nb2 cells and was not an effective inhibitor of prolactin-induced proliferation. In fact, one preparation of forskolin stimulated proliferation of quiescent Nb2 cells. Like forskolin, prostaglandin E2 did not stimulate cAMP production in Nb2 cells even though, it increased cAMP in a preparation of rat peripheral blood lymphocytes. Cholera toxin appeared to ADP-ribosylate a stimulatory guanine nucleotide-binding protein in Nb2 cells, but the toxin did not increase intracellular levels of cAMP nor was it a potent anti-mitogenic agent. Pertussis toxin, an agent that can increase cAMP production through suppression of the inhibitory guanine nucleotide-binding protein, exerted only minor anti-proliferative actions on prolactin-stimulated Nb2 cells. These data suggest that cAMP inhibits Nb2 cell proliferation and prolactin-induced changes in protein phosphorylation but that the adenylate cyclase system in our clone of Nb2 cells responds poorly to agents that normally increase cAMP.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240430405
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  • 5
    Electronic Resource
    Electronic Resource
    Structure of the respiratory islets of accessory respiratory organs and their relationship with the gills in the climbing perch, Anabas testudineus (Teleostei, Perciformes) (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 209 (1991), S. 241-256 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The epithelial and sub-epithelial organization of the accessory respiratory organs of Anabas testudineus has been compared with that of gills by using light and transmission electron microscopy. The details of vascular supply of respiratory islets (RI) and gill filaments and the presence of venous sinusoids in the two systems suggest that the RI have been derived from gill filaments and lamellae. The biserial arrangement of transverse capillaries (TC) in the respiratory islets (RI) is evident under the scanning electron microscope and their homology with the gill filaments and their secondary lamellae has been established. The two sets of transverse capillaries of respiratory islets have been derived either from embryonic transverse or marginal channels of two sets of lamellae of a gill filament. These capillaries with their endothelial septate valves and tongue-like processes offer resistance to blood flow.Gill filaments have two vascular pathways, arterio-arterial and arterio-venous. However, the RI of accessory respiratory organs contain the arterio-venous pathways. This arrangement as well as the septate transverse capillaries may lower the “pulmonary” blood pressure considerably.Two types of mitochondria-rich cells are identified: i) chloride cells with flat microvilli bearing surfaces, devoid of apical pit and (ii) an elongated cell type with sac-like endoplasmic reticulum, with apical pit that comes into close contact with the complex matrix of macrophages, lymphocytes and other loose cells of the epithelium. These cells may be associated with detoxification of the internal media of fish inhabiting foul waters.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052090302
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  • 6
    Electronic Resource
    Electronic Resource
    Cell cycle arrest by prostaglandin A1 at the G1/S phase interface with up-regulation of oncogenes in S-49 cyc- cells (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 54 (1994), S. 265-272 
    Details
    ISSN: 0730-2312
    Keywords: DNA synthesis ; cAMP ; cell growth inhibition ; lymphoma ; PGA1 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Our previous studies have implied that prostaglandins inhibit cell growth independent of cAMP. Recent reports, however, have suggested that prostaglandin arrest of the cell cycle may be mediated through protein kinase A. In this report, in order to eliminate the role of c-AMP in prostaglandin mediated cell cycle arrest, we use the-49 lymphoma variant (cyc-) cells that lack adenylate cyclase activity. We demonstrate that dimethyl prostaglandin A1 (dmPGA1) inhibits DNA synthesis and cell growth in cyc- cells. DNA synthesis is inhibited 42% by dmPGA1 (50 μM) despite the fact that this cell line lacks cellular components needed for cAMP generation. The ability to decrease DNA synthesis depends upon the specific prostaglandin structure with the most effective form possessing the α,β unsaturated ketone ring. Dimethyl PGA1 is most effective in inhibiting DNA synthesis in cyc- cells, with prostaglandins PGE1 and PGB1 being less potent inhibitors of DNA synthesis. DmPGE2 caused a significant stimulation of DNA synthesis. S-49 cyc- variant cells exposed to (30-50 μm) dmPGA1, arrested in the G1 phase of the cell cycle within 24 h. This growth arrest was reversed when the prostaglandin was removed from the cultured cells; growth resumed within hours showing that this treatment is not toxic. The S-49 cyc- cells were chosen not only for their lack of adenylate cyclase activity, but also because their cell cycle has been extensively studied and time requirements for G1, S, G2, and M phases are known. Within hours after prostaglandin removal the cells resume active DNA synthesis, and cell number doubles within 15 h suggesting rapid entry into S-phase DNA synthesis from the G1 cell cycle block. The S-49 cyc- cells are known to have a G1/S boundary through M phase transition time of 14.8 h, making the location of the prostaglandin cell cycle arrest at or very near the G1/S interface. The oncogenes, c-fos and c-myc which are normally expressed during G1 in proliferating cells have a 2-3 fold enhanced expression in prostaglandin G1 arrested cells. These data using the S-49 variants demonstrate that dmPGA1 inhibits DNA synthesis and arrests the cell cycle independent of cAMP-mediated effects. The prostaglandin arrested cells maintain the gene expression of a G1 synchronous cell which suggests a unique molecular mechanism for prostaglandin action in arresting cell growth. These properties indicate that this compound may be an effective tool to study molecular mechanisms of regulation of the cell cycle.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240540302
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  • 7
    Electronic Resource
    Electronic Resource
    PBI powder processing to performance parts (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 485-496 
    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 new route (“direct forming”) was developed for forming dense PBI shapes from PBI powder. The new process affords the possibility of automated PBI powder shaping (“cold compaction”) and densification in batches of multiple parts by a “powder-assisted hot isostatic pressing” process. Direct forming is a more productive alternative to hot compression molding. Two developments enable PBI direct forming: (1) the discovery that PBI powders that are porous and plasticized with moisture can be shaped by compaction at ambient temperatures (cold-compacted), and (2) a finding that cold-compacted shapes can be densified in large batches by a powder-assisted hot isostatic pressing. The porous PBI powder is formed from PBI in solution by a spray-precipitation process. When plasticized with moisture, this powder is cold-compactible to PBI shapes with densities up to 94% of that of ultimate density of PBI. These shapes, which have sufficient strength to be handled, are then further consolidated via powder-assisted hot isostatic pressing to shapes with excellent thermal and mechanical properties and densities of about 99% of the ultimate. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530503
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  • 8
    Electronic Resource
    Electronic Resource
    Fibroblasts inhibit mineralised bone nodule formation by rat bone marrow stromal cells in vitro (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 146 (1991), S. 442-450 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ability of rat skin fibroblasts (RSF) and human periodontal ligament fibroblasts (HPL) to inhibit the formation of mineralised bone nodules in rat bone marrow stromal cell (BMSC) cultures was studied. Co-culture of HPL or RSF with BMSC resulted in a large reduction of bone nodule formation when compared with controls. Conditioned medium from HPL or RSF cultures inhibited bone nodule formation in a dose-dependent manner. HPL-conditioned medium depressed cell proliferation and alkaline phosphatase expression in BMSC cultures. These effects were not due to increased cytotoxicity or nutrient depletion. Inhibitory activity was recovered in a fraction of less than 1 kD following ultrafiltration and was insensitive to freeze-thawing. The inhibitory activity was blocked when HPL cultures were grown in the presence of 105M indomethacin. Dose-dependent inhibition of bone nodule formation was also observed in cultures incubated with prostaglandins E2 (at 10-6M) or F2α(at 10-7). The results indicate that fibroblasts may inhibit osteoblast differentiation and function in part by release of soluble factors including prostaglandins.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041460315
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  • 9
    Electronic Resource
    Electronic Resource
    Bindings of the lectins Griffonia simplicifolia-1 and pokeweed mitogen mark discrete stages of myoepithelial-like differentiation of cell lines from the rat mammary gland (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 146 (1991), S. 222-233 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Individual single-cell-cloned cell lines of the different rat mammary (Rama) cell types have been tested for their ability to bind the lectins Griffonia simplicifolia-1(GS-1) and pokeweed mitogen (PWM) using fluorescent, histochemical, and radioactive assays. Myoepithelial-like cell lines isolated from neonatal rat mammary glands and from nonmetastasizing tumors strongly bind GS-1 and PWM, whereas the corresponding epithelial and fibroblastic cell lines do not. When the epithelial cell lines are grown on floating gels of polymerised rat tail collagen, the basally situated or peripheral cells are stained strongly with peroxidase-conjugated lectins, whereas the apically or luminally situated cells are unstained. The capacity of cell lines intermediate in morphology between epithelial and myoepithelial-like cells to bind to GS-1 is as follows: Rama 25 epithelial 〈 Rama 25-12 〈 Rama 25-I1 〈 Rama 25-14 〈 Rama 29 myoepithelial-like cells, the same order as for other markers of myoepithelial cells. Conjugated PWM, however, binds only to the myoepithelial-like cell lines. Treatment of Rama 25 epithelial cells with agents that disrupt microtubules accelerates their conversion to elongated, myoepithelial-like cells in culture. The binding of cells to GS-1 is observed prior to, and that to PWM after, the major morphological change. It is suggested that the stepwise appearances of carbohydrate receptors for GS-1 and PWM mark discrete stages in the differentiation of epithelial to myoepithelial-like cells in culture, in the same way that they mark similar differentiation stages in ductal development in mammary glands of prepubertal rats.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041460206
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  • 10
    Electronic Resource
    Electronic Resource
    The effects of heat treatments and bead size on the corrosion of porous F75 in saline and serum (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 79-94 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An accelerated anodic corrosion method was used to study the effects of heat treatment and bead size on corrosion and metal ion release of porous coated F75 cylinders in saline and serum. Three heat treatments were used: a standard process for F75 implants (HTA), the standard plus an additional hour in air to produce a thin oxide film (HTA′), and a sintering in high vacuum to produce a chromium-depleted surface (HTB). Three bead sizes of similar composition were used, with approximate sizes of 215, 300, and 560 μm. The results demonstrated that HTA′ had the lowest corrosion rate and that of HTB was significantly greater than either HTA or HTA′. The corrosion rates of HTA and HTA′ were significantly greater in serum as compared with saline, whereas that of HTB was not affected by the presence of serum, suggesting an interaction between chromium and serum proteins. Bead size had a minimal effect on the corrosion rate of HTA′. For HTA, the small beads had the highest corrosion rate; the lowest was with the medium-sized beads. Bead size had the most significant effect with HTB, with that of the smaller beads having the higher corrosion rates. The effects of bead size were less consistent in serum, suggesting that protein adsorption may mask some of the surface area effects. It is concluded that the oxide film does reduce corrosion, that proteins do have an influence on the corrosion of F75, and that this method can be a suseful tool for studying the effects of improved heat treatment methods on the corrosion rate of F75 implants.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820240108
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