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  • Polymer and Materials Science  (8)
  • Chemical Engineering  (5)
  • Picea glauca  (3)
  • Auxin  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Trees 2 (1988), S. 32-38 
    ISSN: 1432-2285
    Keywords: Auxin ; Cytokinin ; Gymnosperm ; Micropropagation ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Adventitious bud formation was induced on detached cotyledons and on cotyledons attached to excised embryos of Pinus caribaea and Pseudotsuga menziesii. The embryonic tissue was exposed to the cytokinin 6-benzyl amino purine contained within an agar medium. This exposure resulted in the formation of a meristematic zone, involving both epidermal and sub-epidermal cells, and then nodules on the tissue surface. Some of these nodules were induced to differentiate into bud primordia, and thence shoots, following exposure to a combination of auxin (IAA) and cytokinin. Shoots were produced over the entire surface of detached cotyledons of Ps. menziesii but predominantly on the adaxial surfaces of detached cotyledons of Pi. caribaea and the tips and adaxial surfaces of the cotyledons on the entire embryos of both species. Thus, inter-specific differences in the distribution of competent areas for adventitious bud production were detected in embryos.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Trees 2 (1988), S. 32-38 
    ISSN: 1432-2285
    Keywords: Auxin ; Cytokinin ; Gymnosperm ; Micropropagation ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Adventitious bud formation was induced on detached cotyledons and on cotyledons attached to excised embryos ofPinus caribaea andPseudotsuga menziesii. The embryonic tissue was exposed to the cytokinin 6-benzyl amino purine contained within an agar medium. This exposure resulted in the formation of a meristematic zone, involving both epidermal and sub-epidermal cells, and then nodules on the tissue surface. Some of these nodules were induced to differentiate into bud primordia, and thence shoots, following exposure to a combination of auxin (IAA) and cytokinin. Shoots were produced over the entire surface of detached cotyledons ofPs. menziesii but predominantly on the adaxial surfaces of detached cotyledons ofPi. caribaea and the tips and adaxial surfaces of the cotyledons on the entire embryos of both species. Thus, inter-specific differences in the distribution of competent areas for adventitious bud production were detected in embryos.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Abscisic acid ; Endochitinase ; Fungal elicitation ; β-1,3-Glucanase ; Picea glauca ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two cDNAs isolated from white spruce [Picea glauca (Moench) Voss] somatic embryos, are predicted to encode a basic class IV chitinase and a β-1,3-glucanase, respectively corresponding to genesPgChi-1 andPgGlu-1. Each represents a multigene family in spruce. Transcripts homologous toPgChi-1 orPgGlu-1 genes were highly abundant in embryogenic tissues and gradually decreased after tissues were placed on abscisic acid-containing maturation medium, with lowest abundance in globular embryos. Transcripts related toPgGlu-1 became highly abundant again in early cotyledonary embryos but decreased thereafter, whereas transcripts related toPgChi-1 were also highly abundant in late cotyledonary embryos and plantlets in vitro; transcripts were either low (PgChi-1) or were not detectable (PgGlu-1) in needles. Wounding, drying and flooding stresses enhancedPgChi-1-andPgGlu-1-related gene expression. Fungal cell wall suspension enhancedPgGlu-1-related transcript accumulation, but reducedPgChi-1-related transcript abundance within 24 h.PgChi-1 andPgGlu-1 and their homologues may have roles in plant defense, and possibly developmental roles during spruce somatic embryo maturation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 15 (1996), S. 516-521 
    ISSN: 1432-203X
    Keywords: conifer ; Picea glauca ; RNA extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A simple and efficient procedure suitable for extraction of high-quality RNA from cultured conifer tissues, somatic embryos, zygotic embryos, needles, stem and root tissues was developed. It produced from 100 μg up to 700 μg total RNA per gram tissue dependent on the types of tissues used. RNA quality was estimated by spectrophotometry, agarose gel electrophoresis, in vitro translation of mRNA, cDNA synthesis and Northern blot analysis. The method also worked well with Arabidopsis thaliana and tobacco tissues.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5028
    Keywords: embryo-abundant cDNAs ; gene expression ; gymnosperm ; Picea glauca ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six somatic embryogenesis-associated cDNAs (PgEMB2, 6, 7, 8, 24 and 34) from white spruce (Picea glauca (Moench) Voss) somatic embryos have been characterized. Transcript accumulation during somatic embryo development and subsequent germination related to these genes, indicated that they were developmentally regulated. The transcripts related to clones PgEMB2, 6, 24 and 34 were also detected during zygotic embryo development, but transcripts of clones PgEMB7 and 8 were not. PgEMB24 had a similar gene expression pattern to spruce Em-like late embryo abundant (lea) gene, but other clones had no similarities in gene expression to either spruce lea-like or storage protein genes. Abscisic acid, a stimulator for spruce somatic embryo maturation, did not obviously affect gene expression corresponding to these cDNAs. The predicted proteins are distinguishable from known LEA proteins based on analyses of hydropathy plots, amino acid compositions and deduced protein structures. The similarities of the spruce cDNAs, and protein sequences predicted from these cDNAs, to other sequence data are described.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1527-1534 
    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: Measures of mixing for laminar flow are developed from basic principles of continuum mechanics for infinitesimal rates of stretch. The entire analysis is performed from the basis of the eigenvalues and principal directions of the appropriate flow tensors. Measuring the rate of line growth, where the line marks the interface between two miscible fluids, in terms of the major eigenvalue provides a direct measure of the maximum rate of mixing. Two efficiency measures for mixing are derived in terms of the eigenvalues and their directions. The creation efficiency of the magnitude of the major eigenvalue as a function of the energy input into the flow field is evaluated. The orientation of the interface to the principal direction qualifies the mixing efficiency in laminar flow. The new theory is used to analyze two-dimensional and three-dimensional channels. The results demonstrate not only the continuum measures for mixing but also extend our present understanding on mixing and provide future directions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 1270-1278 
    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: Flow in a three-dimensional channel with a sinusoidally-wavy, vertical wall is examined for the case of applied down- and cross-channel velocity components. An important parameter for the analysis of the nature of laminar mixing in the flow field occurs when the changes in the downstream direction can be decoupled from the changes in the cross-channel direction, thereby allowing for a two-dimensional solution of the system of equations. This paper shows the effect on the nature of laminar mixing when the decoupling of the momentum equations from a fully three-dimensional case to one where a two-dimensional solution can be performed. Experiments are performed on a channel with sinusoidally varying vertical walls that cover the range of decoupling criteria. Silicone pigmented either white or black was run in the apparatus, cured, and cross-sectioned. The cross sections embody a local, detailed history of the state of mixing as it proceeds down the mixer. The amount of mixing is presented as a function of position at each cross section for the different channel configurations. The nature of mixing changes from a linear growth rate in the amount of interfacial area to an exponential rate as the amplitude of the wave is increased. Results demonstrate the existence of chaos, islands, and the factors affecting the mixing behavior.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1874-1883 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work, the bimodal/film model is compared with the cell model based on a case study using polystyrene/styrene devolatilization. It shows improvements over the cell model: (1) it requires a lower initial number of bubbles, which is more physically realistic and (2) it takes into account the observation of a limiting foam volume growth for a specific polymer in devolatilization. A stripper dispersion experiment was designed to investigate the effect of dispersed nitrogen stripper bubbles on the foam dynamics and devolatilization efficiency. The variables examined include polymer viscosity, initial volatile concentration, and the initial number and size of dispersed stripper bubbles. Polymer viscosity was the dominant factor in limiting the maximum foam volume expansion. The number and size of dispersed stripper bubbles show positive and negative effects (which are only secondary) on the maximum foam volume expansion, respectively. The initial volatile concentration has no effect on limiting the maximum foam volume expansion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1861-1873 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Volatile species are removed from polymers by devolatilization. Foaming experiments using corn syrup and low-density polyethylene were carried out to investigate effects of volatile content, operating vacuum level and stripping agent in devolatilization. When foaming and rupture occur, a limiting foam volume growth was observed for a polymer regardless of the volatile content and the addition of stripper bubbles. A mathematical model was also developed to study the effect of stripper bubbles in polymer devolatilization. Based on the cell model for bubble growth, a bimodal model for foam growth is developed as the first step to describe the initial formation and growth of the volatile and stripper bubbles in polymer during devolatilization. When foaming and breakup occur at a critical foam volume expansion, a film model for mass transfer is used to model the second step of devolatilization. A numerical factorial study shows that the devolatilization section should be designed and operated to provide the screw channel sufficient free volume and residence time for the desired foam expansion.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 649-659 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Drop breakup mechanisms inside a cavity flow are presented for two immiscible fluids. Due to the nonuniform flow condition of the cavity, the breakup mechanism varied along the streamlines. The streamlines were characterized by stream zones A and B, where zone A possessed a methodical transient breakup governed by Tomotika's breakup via capillary instabilities, and the breakup mechanism of stream zone B consisted of tip streaming breakup, an inefficient breakup mechanism. The flow behavior near flight region had a significant role in the drop breakup mechanisms. The study of the evolution of drop dispersion showed that the matrix viscosity is critical in controlling the transient breakup process and that the shear rate increase had little or no effect on the drop breakup.
    Additional Material: 27 Ill.
    Type of Medium: Electronic Resource
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