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  • Humans  (92)
  • Cell & Developmental Biology  (74)
  • Chemical Engineering  (68)
  • 2010-2014
  • 1990-1994  (234)
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  • 1990  (234)
  • 1
    Electronic Resource
    Electronic Resource
    Enhancing adhesion by ion beam-induced atomic mixing at the interface between copper film and polyimide substrate (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 137-141 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Ion beam mixing was used to improve the adhesion between deposited Cu film (400 Å) and polyimide (PI) substrate. Ar+ ion with the energy levels between 180 and 200 keV, and the dose between 1014 to 4 × 1016 ions/cm2 were used. The surface analyses were carried out by Rutherford Backscattering Spectroscopy (SEM). RBS analysis, using 2 MeV He+ ions, showed mixing of Cu and FI and the mixing depended on the Ar+ energy and dose. The X-ray study showed a very broad halo for deposited Cu film but the (111) peak appeared after the Ar+ implantation and the peak increased with Ar+ ion dose. Optical micrographs showed that Cu film formed circular bubbles after many thermal cycles when adhesion was poor and fracture cracks when adhesion was good.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300302
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization and processing of blends of polyethylene terephthalate with several liquid crystalline polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 519-526 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Blends of an engineering thermoplastic, poly(ethylene terephthalate) (PET), and two liquid crystalline polymers (LCPs) viz., copolyesters of PET and parahydrox-ybenzoic acid (PHB) in 40/60 mole percent (LCP60) and in 20/80 mole percent (LCP80) were prepared. A blend of LCP60 and LCP80 in 50/50 weight percent (LCP60-80) was blended with PET. Both flat films and rods were extruded and their properties examined. The morphology of the films investigated using Scanning Electron Microscopy (SEM) revealed that the LCP phase remained as dispersed droplets in the PET matrix. In spite of the lack of fibrillation in these films, the mechanical properties were enhanced to some extent with a maximum at 10 weight percent of the LCP phase. However, in the case of the rods thin fibrils of the LCP phase of the order of 1 μm in diameter were observed provided the composition of the LCP was 20 weight percent or greater. This success In achieving fibrillation is through to be due to the extensional flow fields present at the entrance of the capillary die and the fact that a short L/D ratio die was used. Differential Scanning Calorimetry (DSC) thermograms of the extruded films indicated that the LCP phase may act as a nucleating agent for the crystallization of PET. Rheology of the blends revealed that the complex viscosity of the blends is not much different from that of pure PET. This is attributed to the partial miscibility of the two components. Based on the DSC results and residence times in the extruder, it is concluded that no significant transesterification reactions appear to have: taken place in the blends. The rheology is studied further with respect to the cooling behavior of the pure components and factors important to the fibrillation of the LCP phase and the formation of in-situ reinforced composites are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300904
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  • 3
    Electronic Resource
    Electronic Resource
    Thermomechanical properties of 1C molding compoundsPresented at the Annual Meeting of American Institute of Chemical Engineers in San Francisco, California on November 6, 1989. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 609-617 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Eight commercial semiconductor grade epoxy compounds that are used to encapsulate 1C (integrated circuit) devices have been evaluated for their ability to minimize the development of thermal stresses which can cause failure during device temperature cycling. Thermal expansion, dynamic modulus and adhesion studies are used to describe the mechanical interaction between the plastic package and the silicon device it surrounds. A “figure of merit” is defined for the development of stress on the 1C device as it is cooled after the packaging process. The stress is shown to be proportional to the product of three terms: (αp-αs) Ep (Tanch-T) where αp and αs are the expansion coefficients for the plastic and silicon, respectively, Ep is the modulus of the epoxy and Tanch is the temperature at which the epoxy becomes anchored to the silicon device during transfer molding. In addition, the importance of good adhesion between the epoxy encapsulant and the silicon device to prevent package cracking has been demonstrated by finite element analysis and a novel adhesion test.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301008
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  • 4
    Electronic Resource
    Electronic Resource
    Comments on “fracture toughness of impact modified polymers based on the J-integral” (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1341-1344 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: In (1), Narisawa and Takemori examined the physical interpretations and some experimental techniques of the J-Integral (ASTM E813-81) as applied to toughened polymers. Their results and conclusions are reexamined and discussed in terms of recent developments in J testing.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760302102
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  • 5
    Electronic Resource
    Electronic Resource
    Upgrading of solvent extracted Athabasca Bitumen by membrane ultrafiltration (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1279-1282 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360821
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  • 6
    Electronic Resource
    Electronic Resource
    Thermodynamics of Lewis acid-base mixtures (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1851-1864 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The associated perturbed-anisotropic-chain theory (APACT) has been applied to treat multicomponent mixtures, in which components exhibit Lewis acid-base interactions. Mixtures of amphoteric molecules (such as alcohols), acidic molecules (such as chloroform), and basic molecules (such as ketones) as well as nonassociating components (diluents) are treated. The acid-base version of the perturbed-anisotropic-chain theory (ABPACT) is a closed form equation of state that takes into account explicitly dispersion interactions, polar interactions, and hydrogen bonding interactions between components that self-associate or solvate. The equation fits binary VLE mixtures quite accurately. Calculated results also are compared with those obtained from the Peng-Robinson equation of state, UNIFAC and the original APACT. In all cases where there are mixtures of associating components, the ABPACT gives a better fit of experimental data than these other equations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690361209
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  • 7
    Electronic Resource
    Electronic Resource
    The reaction-independence of mixing coefficients in fixed-bed reactors (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1449-1451 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360920
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  • 8
    Electronic Resource
    Electronic Resource
    Solidification behavior and recovery kinetics of liquid crystalline polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 989-995 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 supercooling behavior of three thermotropic liquid crystalline polymers (TLCP's), 60 mole% p-hydroxybenzoic acid and 40 mole% poly(ethyleneterephthalate), 60/40 PHB/PET, 80 mole% p-hydroxybenzoic acid and 20 mole% poly(ethyleneterephthalate), 80/20 PHB/PET and a copolyester of 73 mole% p-hydroxybenzoic acid and 27 mole% of 2-hydroxy-6-naphthoic acid, Vectra A900, was studied by means of both rheological and thermal methods. 60/40 PHB/PET and Vectra A900 exhibited a degree of supercooling as high as 80°C while there was only 20°C of supercooling for 80/20 PHB/PET. The degree of supercooling for the blends of 60/40 PHB/PET and 80/20 PHB/PET also decreased with the increase in 80/20 PHB/PET content. The increase in G′ as the temperature decreased was more gradual for 60/40 PHB/PET and Vectra A900 than that for 80/20 PHB/PET, which was beneficial from a processing point of view. The solidification of the LCP melt was attributed to both the crystallization and the freezing of the mesophase. The degree of crystallinity for all three TLCP's was very small, less than 5%, as measured by the DSC. It was found that both 60/40 PHB/PET and Vectra A900 showed an induction period of a few minutes during solidification while 80/20 PHB/PET solidified continuously at the test temperature. Therefore, 60/40 PHB/PET and Vectra A900 seem to be more suitable for use in processes such as blow molding and film blowing than 80/20 PHB/PET.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301608
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  • 9
    Electronic Resource
    Electronic Resource
    Changes in the mitochondrial calcium influx and efflux properties are responsible for the decline in sperm calcium during epididymal maturation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 186-194 
    Details
    ISSN: 1040-452X
    Keywords: Intracellular calcium ; Intracellular pH ; Mitochondira ; Epididymal sperm ; Bovine ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study was undertaken to determine the role of calcium ion, a key regulator of the intensity and form of motility in mature demembranated sperm, in the development of motility during passage through the bovine epididymis. Cellular calcium levels in bovine caput and cauda epididymal spermatozoa were measured with three different techniques. 45Ca2+ uptake measurements revealed that net calcium uptake and Ca2+-Ca2+ exchange in caput spermatozoa were about 2 to 3 times higher than in caudal spermatozoa. Intracellular free calcium determination with the calcium fluorophore Fura 2 showed that the levels were 6 times higher in caput spermatozoa. The values for caput and caudal sperm were 875±55 nM (n = 15) and 155±6 nM (n = 24), respectively. Total cellular calcium levels quantitated by atomic absorption were 626±30 (n = 48) and 304±19 (n = 46) ng/108 sperm in caput and caudal epididymal sperm, respectively. At least one of the reasons for the high calcium content of caput epididymal sperm is the result of a higher rate and extent of mitochondrial calcium accumulation in caput compared to caudal sperm. Mitochondrial calcium uptake rates measured in digitonin permeabilized cells revealed uptake rates 2- to 3-fold higher in caput compared to caudal sperm. However, mitochondrial calcium efflux rates were identical in caput and caudal epididymal sperm. The efflux rates in both cell types were unaffected by external sodium levels but were found to be proportional to pH. Alkalinization or acidification of internal pH of intact sperm resulted in a corresponding lowering or elevation of cytoplasmic free calcium levels. We propose that external calcium has access to sperm only via the mitochondria (Vijayaraghavan and Hoskins: Cell Calcium 10:241-253, 1989) and that this mitochondrial calcium is subsequently redistributed into the cytoplasmic space as a function of the internal pH. We document for the first time that changes in mitochondrial calcium handling properties are important in epididymal sperm maturation and suggest that the acquisition of sperm motility in the epididymis could be related to these changes in sperm calcium handling properties.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250212
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  • 10
    Electronic Resource
    Electronic Resource
    Stimulation of plasma membrane and matrix vesicle enzyme activity by transforming growth factor-β in osteosarcoma cell cultures (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 145 (1990), S. 200-206 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Transforming growth factor-β (TGFβ) serves an important role in extracellular matrix formation by stimulating the production of numerous extracellular matrix proteins by connective tissue cells and by osteoblasts or bone-forming cells. TGFβ has been shown to stimulate alkaline phosphatase (ALPase) activity in the rat osteoblast-like osteosarcoma cell line ROS 17/2.8. Previous studies have shown that this enzyme is elevated during calcification of bone and that it is enriched in matrix vesicles, an extracellular organelle associated with initial hydroxyapatite formation. To test the hypothesis that TGFβ plays a role in regulating mineral deposition in the matrix, the effects of TGFβ on ALPase and phospholipase A2, two enzymes associated with mineralization, were examined. ROS 17/2.8 cells were cultured at high and low density with recombinant human TGFβ (0.1-10 ng/ml) to examine the influence of cell maturation on response to TGFβ. Maximal stimulation of ALPase activity in the low density cultures was seen at 5 ng/ml; in high-density cultures, there was further stimulation at 10 ng/ml. There was a dose-dependent increase in ALPase activity seen in the matrix vesicles and plasma membranes in both types of cultures. Matrix vesicle ALPase exhibited a greater response to factor than did the plasma membrane enzyme. However, in low density cultures, the two membrane fractions exhibited a parallel response with greatest activity consistently in the matrix vesicles. There was a dose-dependent increase in phospholipase A2-specific activity in the plasma membranes and matrix vesicles of both high- and low-density cultures. In agreement with previous studies, TGFβ inhibited cellular proliferation 50%. The results show that addition of TGFβ stimulates the activity of enzymes associated with calcification. The effect of TGFβ is dependent on the stage of maturation of the cell. This study indicates that TGFβ may play an important role in induced bone formation, calcification, and fracture repair in addition to its role in promoting chondrogenesis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041450203
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