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  • Biochemistry and Biotechnology  (4)
  • Beam  (1)
  • Cell & Developmental Biology
  • 2005-2009
  • 1990-1994  (6)
  • 1980-1984
  • 1965-1969
  • 1930-1934
  • 1992  (6)
Collection
Keywords
Publisher
Years
  • 2005-2009
  • 1990-1994  (6)
  • 1980-1984
  • 1965-1969
  • 1930-1934
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effect of gravity on nonlinear oscillations of a horizontal, immovable-end beam (1992)
    Springer
    Nonlinear dynamics 3 (1992), S. 365-373 
    Details
    ISSN: 1573-269X
    Keywords: Beam ; gravity effect ; method of multiple scales ; nonlinear oscillations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A critical problem in designing large structures for space applications, such as space stations and parabolic antennas, is the limitation of testing these structures and their substructures on earth. These structures will exhibit very high flexibilities due to the small loads expected to be encountered in orbit. It has been reported in the literature that the gravitational sag effect under dead weight is of extreme importance during ground tests of space-station structural components [1–4]. An investigation of a horizontal, pinned-pinned beam with complete axial restraint and undergoing large-amplitude oscillations about the statically deflected position is presented here. This paper presents a solution for the frequency-amplitude relationship of the nonlinear free oscillations of a horizontal, immovable-end beam under the influence of gravity. The governing equation of motion used for the analysis is the Bernoulli-Euler type modified to include the effects of mid-plane stretching and gravity. Boundary conditions are simply supported such that at both ends there is no bending moment and no transverse and axial displacements. These boundary conditions give rise to an initial tension in the statically deflected shape. The displacement function consists of an assumed space mode using a simple sine function and unknown amplitude which is a function of time. This assumption provides for satisfaction of the boundary conditions and leads to an ordinary differential equation which is nonlinear, containing both quadratic and cubic functions of the amplitude. The perturbation method of multiple scales is used to provide an approximate solution for the fundamental frequency-amplitude relationship. Since the beam is initially deflected the small-amplitude fundamental natural frequency always increases relative to the free vibration situation provided in zero gravity. The nonlinear equation provides for interactions between frequency and amplitude in that both hardening and softening effects arise. The coefficient of the quadratic term in the nonlinear equation arises from the static (dead load) portion of the deflection. This quadratic term, depending upon its magnitude, introduces a softening effect that overcomes the hardening term (due to initial axial tension developed by deflection) for large slenderness ratios. For very large slender, immovable-end beams, the fundamental natural frequency is greater than that of beams without axial constraints undergoing small amplitude oscillations. This phenomenon is attributed to the stiffening effect of the statically-induced axial tension. However, the stiffening effect of axial tension in beams with slenderness ratios greater than approximately 392 undergoing large-amplitude symmetric-mode oscillations is overpowered by the presence of gravitational loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00045072
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    E.coli hemolysin interactions with prokaryotic and eukaryotic cell membranes (1992)
    New York, NY : Wiley-Blackwell
    BioEssays 14 (1992), S. 519-525 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hemolysin toxin (HlyA) is secreted across both the cytoplasmic and outer membranes of pathogenic Escherichia coli and forms membrane pores in cells of the host immune system, causing cell dysfunction and death. The processes underlying the interaction of HlyA with the bacterial and mammalian cell membranes are remarkable. Secretion of HlyA occurs without a periplasmic intermediate and is directed by an uncleaved C-terminal targetting signal and the HlyB and HlyD translocator proteins, the former being a member of a transporter superfamily central to import and export of a wide range of substrates by prokaryotic and eukaryotic cells. The separate process by which HlyA is targetted to mammalian cell membranes is dependent upon fatty acylation of a non-toxic precursor, proHlyA. This is achieved by a novel mechanism directed by the activator protein HlyC, which binds to an internal proHlyA recognition sequence and provides specificity for the transfer of fatty acid from cellular acyl carrier protein.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950140804
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  • 3
    Electronic Resource
    Electronic Resource
    Improving the detection of proteins after transfer to polyvinylidene difluoride membranes (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 715-717 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: N-Terminal sequence analysis of proteins separated by two-dimensional polyacrylamide gel electrophoresis and transferred onto polyvinylidene difluoride (PVDF) membranes has become the method for molecular characterization of proteins contained in biological samples. However, the proteins of lower abundance cannot be sequenced directly, without improving the technique. We have studied a drying method on several PVDF membranes including Trans-Blott, Immobilon P and Problott. Using Amido Black, Coomassie Brilliant Blue R-250 and Ponceau S, we have obtained, in comparison with the non-dried membranes, an enormous increase in the number of detectable proteins.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501301151
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  • 4
    Electronic Resource
    Electronic Resource
    Human liver protein map: A reference database established by microsequencing and gel comparison (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 992-1001 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: This publication establishes a reference human liver protein map obtained with immobilized pH gradients. By microsequencing, 57 spots or 42 polypeptide chains were identified. By protein map comparison and matching (liver, red blood cell and plasma sample maps), 8 additional proteins were identified. The new polypeptides and previously known proteins are listed in a table and/or labeled on the protein map, thus providing a human liver two-dimensional gel database. This reference map can be used to identify protein spots on other samples such as rectal cancer biopsies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501301201
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  • 5
    Electronic Resource
    Electronic Resource
    Two-dimensional polyacrylamide gel electrophoresis reveals differences between osteoblast and fibroblast extracellular proteins (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 329-332 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Normal human skin fibroblast primary cell lines secrete over 50 proteins into culture medium. These have been mapped previously using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and this technique has now been used to investigate extracellular protein secretion by human osteoblasts in vitro. We report the mapping of a number of consistent markers specific to the osteoblast. In particular, one protein chain with posttranslational modifications was found to be unique to the osteoblast extracellular protein map. The absence of the N- and O-glycoforms of collagenase from the osteoblast profile in this study concurs with findings reported using the immunoprecipitation functional assay and Northern blot analysis. The use of 2-D PAGE in phenotypic assessment provides a more complete analysis than the standard range of single-parameter tests for osteobiasts. Mapping of extracellular and cellular proteins in addition to bone matrix protein analysis will allow a comprehensive analysis of normal osteoblast function. This technique may also be applied to the study of osteoblasts in relation to bone disease and in assessing the phenotypic shift within a normal osteoblast culture.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150130165
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  • 6
    Electronic Resource
    Electronic Resource
    Plasma protein map: An update by microsequencing (1992)
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 707-714 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The reference plasma protein map, obtained with immobilized pH gradients in the first dimension of two-dimensional electrophoresis, is presented. By microsequencing, more than 40 polypeptide chains were identified. The new polypeptides and previously known proteins are listed in a table and labeled on the protein map, thus providing an update of the human plasma two-dimensional gel database.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501301150
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