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  • Open Access

    ABSTRACT

    Molecular Dynamics Simulations of Carbon Nanotubes Cross-Bonding by Proton Irradiation

    N. J. Lee, C.R. Welch1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.1, pp. 11-12, 2009, DOI:10.3970/icces.2009.013.011

    Abstract Carbon nanotubes have significant potential as the basis for super infrastructure material. The shear modulus of carbon nanotube ensembles is relatively low, comparable to graphite, as the carbon nanotubes interact via weak van der Waals forces. Unmodified, their intermolecular interactions are insufficient to take full advantage of the extraordinarily high strengths predicted for carbon nanotube-based fibers. Thus, a key to their use in high-strength materials is developing strong bonds between these molecules. In this study, we examine the potential development of covalent bonds between carbon nanotube pairs cross-bonded by proton bombardment using molecular dynamics simulation. More >

  • Open Access

    ARTICLE

    Isolation of epithelial cells, villi and crypts from small intestine of pigeons (Columba livia)

    OSCAR MAC DONAL1, JUAN G. CHEDIACK1,2,3, ENRIQUE CAVIEDES-VIDAL1,2,3

    BIOCELL, Vol.32, No.3, pp. 219-227, 2008, DOI:10.32604/biocell.2008.32.219

    Abstract The isolation of viable enterocytes, villi and crypts from the small intestine of a feral bird (Columba livia) is important for performing physiological experiments in ecologically relevant processes of membrane transport. The effectiveness of mechanical disruption, enzymatic digestion and chelating agents were compared. The objectives were to isolate enterocytes, villi and crypts from the small intestine of young pigeons; to evaluate the viability of the isolated intestinal epithelial cells isolated; and to verify the integrity of enterocytes by biochemical features. Enzymatic and mechanical methods yielded both elongated columnar and spherical cells. With the chelating method villi More >

  • Open Access

    ARTICLE

    Characterization of associated environments to natural populations of Pavonia cymbalaria (Malvaceae) in rangelands of Sierra de la Ventana (Buenos Aires)

    Torres1 YA, MA Long2, SM Zalba1

    Phyton-International Journal of Experimental Botany, Vol.77, pp. 225-240, 2008, DOI:10.32604/phyton.2008.77.225

    Abstract The objective of this work is to contribute to the biology of Pavonia cymbalaria A. St. Hil & Naudin (Malvaceae), a native species of the Southern mountains of Buenos Aires Province. This knowledge will contribute to (1) promote its use as an ornamental species, (2) its conservation and (3) stimulate the interest and public valuation of mountain systems biodiversity. Seven populations of P. cymbalaria were selected. Two of them were growing under Pinus halepensis forests to characterize different environments were the herbaceous species is growing in the wild. Environmental characteristics immediately associated to six individuals of the species More >

  • Open Access

    ARTICLE

    Reproduction of Pavonia cymbalaria (Malvaceae), a native species with ornamental potential

    Torres, YA1, MA Long2, SM Zalba1

    Phyton-International Journal of Experimental Botany, Vol.77, pp. 151-160, 2008, DOI:10.32604/phyton.2008.77.151

    Abstract Pavonia cymbalaria A. St.-Hil. & Naudin (Malvaceae) is a native species of the southern mountains in the Province of Buenos Aires. Its morphological characteristics become it as a potential candidate for ornamental use. Crop requirements and seed germination were evaluated for this species in this study. Different treatments were applied to 640 mericarps: removal of carpel residues, mechanical scarification or exposition of mericarps and nude seeds to cold conditions. An untreated control was used for each of these treatments. Germination only occurred on nude seeds; this implies the existence of an extrinsic dormancy imposed by the… More >

  • Open Access

    ABSTRACT

    Kinematic Analysis of Lumbar Spine Undergoing Extension and Dynamic Neural Foramina Cross Section Measurement

    Yongjie Zhang1, Boyle C. Cheng2, Changho Oh1, Jessica L. Spehar2, James Burgess3

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.2, pp. 57-62, 2008, DOI:10.3970/icces.2008.007.057

    Abstract The spinal column plays a vital biomechanical role in the human body by providing structural support and facilitating motion. As degenerative changes occur in the spine, however, chronic pain can result which frequently forces patient to seek surgical treatment. Such treatments seek to address that pain, frequently by addressing both spinal motion and structural integrity. More >

  • Open Access

    ARTICLE

    Kinematic Analysis of Lumbar Spine Undergoing Extension and Dynamic Neural Foramina Cross Section Measurement

    Yongjie Zhang1, Boyle C. Cheng2, Changho Oh1, Jessica L. Spehar2, James Burgess3

    CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 55-62, 2008, DOI:10.3970/cmes.2008.029.055

    Abstract The spinal column plays a vital biomechanical role in the human body by providing structural support and facilitating motion. As degenerative changes occur in the spine, surgical treatment may be necessary in certain instances. Such treatments seek to address pain, frequently through the restriction of spinal motion. Traditional spinal implant devices are designed to restrict the motion of a functional spinal unit (FSU) but newer device designs allow for semi-constrained motion such as spinal arthroplasty devices. In this study, a sequence of fluoroscopic imaging data was recorded during the flexibility protocol with an interspinous process… More >

  • Open Access

    ARTICLE

    Transgenic wheat plants resistant to herbicide BASTA obtained by microprojectile bombardment

    MARIANA N. MELCHIORRE, HERNÁN R. LASCANO, VICTORIO S.TRIPPI

    BIOCELL, Vol.26, No.2, pp. 217-223, 2002, DOI:10.32604/biocell.2002.26.217

    Abstract Wheat (Triticum aestivum) transgenic plants of an important commercial cv (Oasis) was obtained with an efficient and short procedure. First, the optimum conditions for the embriogenic calli generation from inmature embryos with a high regeneration percentage were established. The transformation of calli was performed by high velocity microprojectile bombardment, using the pAHC25 plasmid, which contains the reporter gene β-glucuronidase (GUS) and the selectable BAR gene which confers resistance to the herbicide Basta. The transformations were confirmed by β-glucuronidase assay activity, PCR and Southern blot analysis. The efficiency of this procedure was high and similar to other More >

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