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  • Polymer and Materials Science  (46)
  • bic Book Industry Communication::J Society & social sciences::JN Education  (6)
  • 2020-2024  (6)
  • 1990-1994  (37)
  • 1975-1979  (8)
  • 1970-1974  (1)
  • 1
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    Identificación y Recuperación de Valores Ancestrales Afrocolombianos en la Región Pacífico (2022)
    Universidad Santiago de Cali | Lenguajeando mediación pedagógica
    Details
    Publication Date: 2024-03-29
    Description: Based on the roots and convictions of the researchers - the rhizomatic study ventured into the identification and recovery of Afro-Colombian ancestral values in the Pacific Region (Colombia), generating two sequential and complementary stages for this purpose: language contact with elders and older adults from two Ancestral Black Communities Councils in Buenaventura and in La Playa respectively (Valle-Colombia), and the subsequent pedagogical mediation with young people from the Ancestral Black Communities Council of La Bocana (Valle-Colombia). From a rhizomatic methodological structure based on the positions of Deleuze andGuattari (2005), the respective interactions were conducted in a holistically way, under the recovery of human networks and language, in addition to dynamics such as the cane handover, all of the former with strong roots in the praxis of Afro-Colombian communities in general. The obtained results led to significant findings both at the axiological level, and in the terms of emerging cultural elements, in its final phase the research allowed to assertively show the realization of padagogical mediations achieving to reaffirm and recover the Afro-Colombian ancestral values in the context of their new generations.
    Description: Published
    Description: Dadas las raíces y convicciones de los investigadores, el estudio rizomático incursionó en la identificación y recuperación de los valores ancestrales afrocolombianos en la Región Pacifico (Colombia), generándose para el efecto dos etapas secuenciales y complementarias: el contacto de lenguajeo con ancianos y adul-tos mayores de dos Consejos Comunitarios Ancestrales de Comunidades Negras, respectivamente de Buenaventura y de La Playa (Valle–Colombia), y la posterior mediación pedagógica con jóvenes del Consejo Comunitario Ancestral de Comunidades Negras de La Bocana (Valle–Colombia). Desde una estructura metodológica rizomática asentada en las posturas de Deleuze y Guattari (2005), las respectivas interactuaciones de adelantaron de manera holística, bajo la recuperación de tejidos humanos y lenguajeos, además de dinámicas como el paso del bastón, todas con fuerte arraigo en las praxis de las comunidades afrocolombianas en general. Los resultados obtenidos conllevaron a significativos hallazgos tanto a nivel axiológico, como en cuanto a elementos culturales emergentes, y siendo que en su fase final la investigación permitió mostrar de manera asertiva la realización de mediaciones pedagógicas que logran reafirmar y recuperar los valores ancestrales afrocolombianos en el contexto de sus nuevas generaciones.
    Keywords: Afrocolombianos ; Identificación ; Recuperación ; Región Pacífico ; Valores Ancestrales ; bic Book Industry Communication::J Society & social sciences::JN Education ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: Spanish
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    E-BOOK
  • 2
    Electronic Resource
    Electronic Resource
    New oligomers with isatin. Condensation reactions of thiophene and 2,2′-bithiophene with isatin (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 178 (1990), S. 1-16 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die seit langem in der Literatur als “Indophenin-Reaktion” bekannte Umsetzung von Isatin mit Thiophen wurde systematisch untersucht und auf die Umsetzung mit Bithiophen erweitert. Die Reaktionsprodukte wurden isoliert und durch FT-IR, UV, 1H-NMR, 13C-NMR sowie GPC charakterisiert.Im Gegensatz zu den Literaturdaten wurden Reaktionsprodukte mit höheren Molgewichten und anderer Molmassenverteilung gefunden. Die Reaktionsbedingungen - Lösungsmittel, Temperatur und Konzentration - sind für den Reaktionsablauf und die entstehenden Produkte von entscheidender Bedeutung.Füur die oligomeren Reaktionsprodukte werden neue Strukturen vorgeschlagen, die in Übereinstimmung mit allen analytischen Daten sind. Anhand eines Formelschemas werden die Reaktionen des Isatins mit Thiophen (Bithiophen) erläutert.
    Notes: A systematic study of the well-known indophenin reaction between isatin and thiophene was extended to embrace bithiophene. The products of the reactions were isolated and characterized by FT-IR, UV, 1H-NMR, 13C-NMR, and GPC. The values of the thus determined molar masses and molar mass distributions differed from the data given in the literature. The reaction conditions - solvent, temperature, and concentration - are of crucial importance for the course of the reaction and the products obtained.New structures suggested for the oligomeric reaction products agree with all the analytical data. The reactions between isatin and thiophene (bithiophene) are explained schematically.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051780101
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  • 3
    Electronic Resource
    Electronic Resource
    Computer simulation of hydrodynamic properties of semiflexible macromolecules: Randomly broken chains, wormlike chains, and analysis of properties of DNA (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 883-900 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The translational and rotational diffusion coefficients and the intrinsic viscosity of semiflexible, randomly broken, and wormilike chains have been obtained by Monte Carlo simulation in the context of the rigid-body treatment. Both approximate and rigorous rigid-body hydrodynamics are used, so that the error introduced by the approximate methods can be evaluated. A randomly broken chain and a wormilike chain having the same contour length and persistence length have the same radius of gyration but different values for any of the hydrodynamic properties. The two types of chains are compared in this regard. Considering that the cross section of the chain is represented by a cylinder better than by a string of spheres, we devise a cylindrical correction to be applied to the results simulated for chains of beads. Application is made to the analysis of experimental data for the translational and rotational coefficients of DNA fragments with up to 103 base pairs, obtaining the persistence length for each model. The values for the wormlike chain agree well with model-independent values obtained from radii of gyration and with other literature data at varying ionic strength. The randomly broken chain is equally able to reproduce the experimental length dependence of the properties, but the resulting persistence length may be too high.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290603
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  • 4
    Electronic Resource
    Electronic Resource
    Polyene sequence distribution in degraded poly(vinyl chloride) as a function of the tacticity (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2937-2945 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Four fractions of poly(vinyl chloride) (PVC) having appreciably different tacticity distributions were prepared by selective extractions on samples polymerised at temperatures between +60 and -50°C. They were degraded thermally at 180°C in the solid state to conversions in the range 0,2 to 0,5% and in solution at 200°C to conversions in the range 1,6 to 5%. The polyene sequence distribution was investigated by ultra violet/visible (UV/VIS) and resonance Raman spectroscopy. The results show that the type of polyene sequence distribution depends markedly on the tacticity distribution of the polymer. Cross-linking reactions occur more readily as the syndiotacticity increases. The results are discussed and interpreted with reference to previous work relating degradation processes and tacticity.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021801215
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  • 5
    Electronic Resource
    Electronic Resource
    Theoretical approach to cationic polymerization of alkenylfuranes (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 281-287 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular species proposed for the initial steps in the cationic polymerization of alkenylfurans were modeled by MNDO theoretically fully optimized structures. It was confirmed that the anomalous reactivity of ring C-5 of the monomers is determined by HOMO electron densitites, whereas calculated proton affinities from the semiempirical heats of formation fail to explain the low temperature experimental behavior of 2-vinylfuran (1c) from the point of view of stability of intermediate species. However, ab initio 4-31G calculations of proton affinities agree with the experimental facts and allow further explanations of the reactivity of furan derivatives in electrophilic media.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910202
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  • 6
    Electronic Resource
    Electronic Resource
    Blends of poly(hydroxy ether of bisphenol-A) with poly(2-vinylpyridine) and poly(4-vinylpyridine) (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 501-510 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(hydroxy ether of Bisphenol-A), so-called Phenoxy resin (structure-based IUPAC name: poly[oxy(2-hydroxytrimethylene)oxy-1,4-phenyleneisopropylidene-1,4-phenylene]), is shown to be miscible with poly(4-vinylpyridine) (P4VPy, poly[1-(4-pyridyl)ethylene]) and poly(2-vinylpyridine) (P2VPy, poly[1-(2-pyridyl)ethylene]) over the entire composition range. Miscibility of the blends is evidenced by their glass transition temperatures being intermediate between the pure polymers for the blends of P4VPy and Phenoxy but being higher than the average for the case of the P2VPy/Phenoxy blends. Hydrogen bonding between the components was detected through infrared spectroscopy, which was also used in the study of mixtures of low-molecular-weight analogues, in order to calculate the free energies of mixing according to the association model of Painter and Coleman.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940213
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  • 7
    Electronic Resource
    Electronic Resource
    Acetylene-terminated amide oligomers (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 953-962 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Six new acetylene-terminated (AT) oligomers were synthesized by reaction of 3-ethynylbenzoyl chloride and 4-ethynylbenzoyl chloride with three aromatic diamines containing four aromatic rings. The functionalization led quantitatively to AT oligomeric diamides of well defined composition, as confirmed by IR, 1H NMR and 13C NMR spectroscopy. The materials exhibited comparatively high melting points, over 200°C; thus, heating promoted curing before melting or simultaneously with melting, with the only exception of one sample that could be isolated in the amorphous state. Heating at 325°C led to insoluble cured materials, with excellent thermal resistance and glass transition temperatures Tg around 300°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940318
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  • 8
    Electronic Resource
    Electronic Resource
    Composites from furfuryl alcohol and inorganic solids by cationic initiation, 2Part 1: cf. ref.1.. Spectroscopic studies of poly(furfuryl alcohol)-silica composites obtained by trifluoroacetic acid initiation (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1537-1544 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Furfuryl alcohol polymerizes in a suspension of dispersed inorganic solids such as silica in 1,2-dichloroethane using trifluoroacetic acid as initiator. Depending on the experimental conditions the reactions load to (1) agglomeration of particles, (2) composite and soluble polymer formation, (3) composite formation. The chemical structure of the soluble polymers is not regular but the furfurylic sequence is predominant. The polymer grafted on the surface of the solid is a strongly reticulated poly(furfuryl alcohol), which also possesses conjugated double bonds that are involved in an acid-base equilibrium with trifluoroacetic acid.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021940602
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  • 9
    Electronic Resource
    Electronic Resource
    Polymerization of furfuryl alcohol with trifluoroacetic acid: the influence of experimental conditions (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1-9 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Furfuryl alcohol was polymerized by trifluoroacetic acid in methylene chloride to give a colored polymer. This polymer possesses two main sequences in which the furan rings are connected by methylene groups (sequence 1) or by dimethylene ether groups (sequence 2). The polymer is not linear but highly branched, as detected by 1H and 13C NMR spectroscopy. Variations of the experimental conditions, such as the presence of air, the trifluoroacetic acid concentration, the reaction temperature and the solvent, do not allow a significant increase in the linear structure of the polymer. However, an increase in the acid concentration or an increase in temperature produce a decrease in the ether-bridged structure (sequences 2).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930101
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  • 10
    Electronic Resource
    Electronic Resource
    Polymer precursor synthesis of alumina fibers (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 495-503 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High strength alumina fibers were fabricated with a polymer precursor process which was monitored with 13C-NMR, elemental analysis, gas evolution, SEM, and X-ray diffraction. Methylaluminoxane was chain extended by reaction with H2O, the unreacted methyl groups were converted to propanoyloxyl and i-propanoyl groups in molar ratios of 0.2 : 0.8 to 0.4 : 0.6 to afford spinning dope of adequate fluidity which can be spun into filaments with suitable stability. These precursor fibers were hydrolyzed in two stages at ambient temperatures and at 320-350°C, and then calcined at 950°C. The resulting alumina fibers have average tensile strengths up to 1.1 GPa and modulus of greater than 140 GPa.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290406
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