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  • ASFA_2015::G::Geomorphology  (10)
  • Polymer and Materials Science  (7)
  • Ecology  (5)
  • Glutamate synthase  (4)
  • 1
    Publication Date: 2021-05-19
    Description: Se presentan los resultados del análisis del comportamiento de las playas en el sector comprendido entre Barranquilla (Bocas de Ceniza) y la Flecha de Galerazarnba. Se levantaron 24 perfiles perpendiculares ala línea de costa durante los dos períodos climáticos característicos (seco y húmedo). En época seca, bajo la influencia de los vientos alisios, las playas pierden su berma y experimentan un retroceso significativo de su frente, en algunos casos del orden de decenas de metros exhibiendo un perfil cóncavo. En la época húmeda, cuando los vientos se debilitan, las playas se reconstruyen y exhiben en su morfología un perfil convexo. Entre Bocas de Ceniza y Santa Verónica las pendientes son suaves y están asociadas a sedimentos finos, mientras que en el sector sur aumenta el gradiente y el tamaño de grano en el frente de playa.
    Description: The results of analysis about the behavior of the beaches in the sector between Barranquilla (Bocas de Ceniza) and flecha de Galerazamba are presented. Twentyfour profiles perpendicular to the coastline were taken between both seasonal períods (dry and humid). On the chy period, under the influence of the westerlies, the beaches lose their berm and experience a significant retrogression on their foreshore, sometimes in the order of tens of meters, exhibiting a concave profile. On the humid season, when the easterlies weaken, the beaches bulld up and exhibit a convex profile in their morphology. Between Bocas de Ceniza and Santa Verónica the slof and are soft and are associated with fine sediment, while on the southern sector the gradient and the size of the grain increase on the foreshore.
    Description: Published
    Keywords: Nivel del mar. ; Vientos ; Oleaje ; Erosión ; Sedimentos ; ASFA_2015::G::Geodynamics ; ASFA_2015::G::Geomorphology ; ASFA_2015::M::Meteorology
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: pp.23-38
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  • 2
    Publication Date: 2021-05-19
    Description: Los procesos costeros de diferente intensidad producen efectos sobre la línea de costa de cualquier región que de una u otra forma afectan su economía. El balance erosión-sedimentación de las playas se encuentra íntimamente ligado a la hidrodinámica del mar y a su interacción con la atmósfera, complementando de esta forma el sistema costa-mar-aire. En el presente documento se relacionan los principales resultados contenidos en el estudio de las características hidrodinámicas y geológicas del Golfo de Urabá, llevado a cabo entre 1988 y 1989 en cooperación con la Misión Técnica Francesa. Este estudio ha permitido identificar la formación de prismas de acrecimiento sedimentario principalmente en los alrededores de los deltas de los ríos Atrato y Turbo, así como definir las condiciones oceanográficas durante las épocas húmeda y media, además de determinar las características morfológicas del lecho marino.
    Description: The coastal process of different intensity are responsible of effects over the coast line in a region which in a way or another affect their economy. The erosion-deposition balance in the beaches is close related to the hidrodinamics of the sea and the interaction with the atmosphere, completing in this way the sistem coast-sea-air. Is this document a relatioship between the main results obtained in the study of the hidrodinamic and geological characteristics of the Gulf of Urabá is presented, carried out between 1988 and 1989 with the cooperation of the French Technical Mission. This study permited to identify the formation of sedimentary accresion prism mainly in the surroundings of the deltas of the Atrato and Turbo rivers, as to define the oceanographical conditions during the humid and dry seasons, and also determine the morphological characteristics of the marine bottom.
    Description: Published
    Keywords: Temperatura ; Salinidad ; Corriente oceánica ; Río Atrato ; ASFA_2015::G::Geomorphology ; ASFA_2015::G::Geodynamics ; ASFA_2015::H::Hydrology
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: Pp.79-90
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  • 3
    Publication Date: 2021-05-19
    Description: En este informe se presentan los resultados obtenidos a partir de un estudio meteorológico, oceanográfico y sedimentológico del golfo de Morrosquillo durante la época seca (feb/93), cuando la velocidad y dirección del viento actuaron como factores determinantes en la circulación de las aguas, la cual se definió a partir de los siguientes parámetros: Distribución de los campos halinos y térmicos, tránsito de los sedimentos depositados sobre la superficie del lecho marino, repartición horizontal y vertical de la turbidez, determinada con base en muestras de campo y calibración y análisis de una imagen de satélite SPOT. El análisis morfológico efectuado mediante la comparación del trazado de la línea de costa sobre imágenes de satélite y fotografías aéreas a diferentes años, permitió establecer las principales variaciones morfológicas en esta zona. Por efecto de difracción y refracción del oleaje frente a Punta San Bernardo y de compensación al llegar a la fecha de Mestizos, el flujo originado por estos vientos produce dos direcciones principales de corrientes: Una en sentido sureste a partir de la Punta San Bernardo, que se desplaza por la costa este del Golfo y la otra en dirección este, bordeando la costa sur y sureste. Los principales cambios morfológicos de la línea de costa se presentaron en el sector sur del Golfo. Como resultado de los procesos de acrecimiento sedimentario se originó a partir de 1938 el delta del Río Sinú al desembocar por la zona de Tinajoes, el cual actualmente continúa su evolución. Los fenómenos erosivos han afectado considerablemente el cuerpo de la flecha de Mestizos, la terraza marina al este de la espiga y el sector de playas entre Coveñas y Tolú.
    Description: This report presents the results from a meteorological and sedimentological study, of the gulf of Morrosquillo during the dry, season (February/93), where the speed and direction of the wind acted as determinant factors in the circulation of the waters, which was defined from the following parameters: Distribution of the (haline) and thermal fields, transit of the sediment deposited on the surface of the marine botton, horizontal and vertical repartition of turbidity, determined on samples and gauging and analysis of a SPOT satellite image. The morphologic analysis through the comparison of the coastal line images and aereal photographies from differents years, allowedto establish the principal coastal morphologic variations in these zones. The effect of difraction and refraction of the surf front the punta San Bernardo and the compensation arriving to the Mestizos arrow, and the flow originated by the winds produces two principal currents: One in direction south-east starting from punta San Bernardo, that is displaced toward the east of the Gulf and the other east skirting the coast south and south-east. The principal morphological changes of the coastal line were introduced in the south sector of the Gulf. As result of the process of sedimentary acretion originated starting 1938 the delta of the Sinú river as its discharge in the Tinajones zone, evolution that continues. The erosive phenomen on has affected considerably the body of the Mestizos arrow, the marine terrace east of the spike and the sector of beaches between Coveñas and Tolú.
    Description: Published
    Keywords: Costa ; Erosión. ; Río. ; ASFA_2015::G::Geomorphology ; ASFA_2015::P::Physical oceanography ; ASFA_2015::M::Meteorology
    Repository Name: AquaDocs
    Type: Journal Contribution , Not Known
    Format: Pp.93-113
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular 957 (1988), S. 152-157 
    ISSN: 0167-4838
    Keywords: (C. reinhardtii) ; Antigenic similarity ; Ferredoxin dependent enzyme ; Glutamate synthase ; Nitrite reductase
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Plant Science 95 (1993), S. 9-21 
    ISSN: 0168-9452
    Keywords: Chlamydomonas reinhardtii ; Glutamate synthase ; Immunoaffinity purification ; Immunological comparison ; Nitrite reductase ; Proteolysis
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2048
    Keywords: Chlamydomonas (ferredoxin-glutamate synthase) ; Ferredoxin-glutamate synthase ; Glutamate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ferredoxin-glutamate synthase (EC 1.4.7.1) from Chlamydomonas reinhardii has been purified to electrophoretic homogeneity, with a specific activity of 10.4 units mg-1 protein, by a method which included chromatography on diethylaminoethyl sephacel and hydroxylapatite, and ferredoxin-sepharose affinity treatment. The enzyme is a single polypeptide chain of M r 146000 dalton which shows an absorption spectrum with maxima at 278, 377 and 437 nm, and an A276/A437 absorptivity ratio of 7.0. The anaerobic addition of dithionite results in the loss of the absorption peak at 437 nm, which is restored upon reoxidation of the enzyme with an excess of 2-oxoglutarate, alone or in the presence of glutamine. This indicates the presence in the enzyme of a flavin prosthetic group, which is functional during the catalysis. The ferredoxin-glutamate synthase can be assayed with methyl viologen, chemically reduced with dithionite, but it is unable to use reduced pyridine nucleotide. Azaserine, 6-diazo-5-oxo-norleucine, bromocresol green and p-hydroxymercuribenzoate are potent inhibitors of this activity, which, on the other hand, is stable upon heating at 45°C for 10 min.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2048
    Keywords: Amidotransferase ; Amino-terminal sequences ; Chromosomal assignment ; Glutamate synthase ; Hordeum (mutants) ; Photorespiration mutants (barley) ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The NH2-terminal sequences of ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) purified from barley (Hordeum vulgare L.) and Chlamydomonas reinhardtii (Dangeard), and of a barley peptide, were determined and the barley sequences were used to design oligonucleotide primers for the polymerase chain reaction. A specific 1.3-kilobase (kb) cDNA fragment specifying the NH2-terminal one-third of the mature barley polypeptide, was amplified, cloned and sequenced. The NH2-terminus of plant Fd-GOGAT is highly conserved and homologous to the NH2-terminus of the heavy subunit of Escherichia coli NADPH-GOGAT. Based on sequence homologies, we tentatively identified the NH2-terminal region of Fd-GOGAT as the glutamine-amidotransferase domain, which is related to the corresponding domain of the purF-type amidotransferases. The Fd-GOGAT cDNA clone, and polyclonal antibodies raised against the barley enzyme, were used to analyse four Fd-GOGAT-deficient photorespiratory mutants. Three mutants (RPr 82/1, RPr 82/9 and RPr 84/82) had no detectable Fd-GOGAT protein in leaves, while the fourth (RPr 84/42) had a small amount of cross-reacting material. Hybridization to Northern blots of total leaf RNA revealed that both RPr 82/9 and RPr 84/82 were indistinguishable from the parental line (Maris Mink), having normal amounts of a 5.7-kb mRNA species. On the other hand, RPr 82/2 and RPr 84/42 each contained two distinct hybridizing RNA species, one of which was larger than 5.7 kb, the other smaller. Using a set of wheat-barley telosomic addition lines we have assigned the Fd-GOGAT structural locus to the short arm of chromosome 2.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To improve the knowledge of emulsion copolymerization of monomers both swelling their copolymers, but which are of quite different polarity (water solubility), a series of styrene (S)/methyl acrylate (MeA) copolymerizations was carried out in batch at 50°C with potassium persulfate as initiator. The overall rates of copolymerization increase with the amount of MeA in the monomer feed. Copolymer composition follows the usual copolymerization equation if bulk/solution reactivity ratios (rij) and monomer partition between aqueous and organic phase are taken into account (simulation). However, accurate kinetic data at low conversion (gas chromatography) put in evidence an enhanced polymerization of the more hydrophilic monomer (MeA), which can be attributed to polymerization in the water phase. Particle sizes increase with conversion and tend to a limiting value, the higher the MeA content is. Particle number (Np), which is practically constant with conversion of S homopolymerization, tends to increase with MeA content as polymerization proceeds. This trend is enhanced if the emulsifier (sodium dodecanesulfonate, SDS) concentration is increased. Overall propagation rate constants were estimated as function of the experimental conditions and monomer concentration within the particles. From kinetic data (rate of polymerization) and Np, it was found that the average number of radicals per particle, ñ, remains close to 0,5. It was then possible considering S(kp = 125 1 · mol-1 · s-1) as a standard monomer, to estimate the polymerization rate constant for MeA (335 1 · mol-1 · s-1). Since adsorption of emulsifier was shown to be closely related to particle surface composition, the specific area As of SDS was measured on latices at various conversions and initial monomer feeds. As conversions increases, the particle surface appears to be richer and richer in MeA, which corresponds to a particle structuration. Strong and weak acid group titration is also in quite good agreement with the colloidal behaviour.
    Additional Material: 11 Ill.
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of emulsion copolymerizations of styrene (S) with methyl acrylate (MeA) initiated by the redox system potassium persulfate (KPS)/sodium hydrogen disulfite (SBS) was carried out at 50°C. The monomer feed composition and the monomer/water (M/W) ratios were widely varied. The polymerization rate was found to be higher than in the case when only KPS was applied. Initial (influence of polymerization in water phase) and final copolymer molecules (accumulation of MeA in the feed due to a lower reactivity) are richer in the more hydrophilic monomer (MeA). It could be shown that a high water solubility makes the emulsion reactivity ratios to be “apparent” kinetic parameters, which result in a higher number of azeotropic compositions, compared to bulk or solution, according to the M/W ratio. Particle sizes are smaller and the size distribution is larger than in polymerizations in the presence of KPS alone. Particle number (Np) tends to increase with conversion for monomer mixtures rich in MeA, contrary to S homopolymerizations in which Np remains constant. Comparison of Np and kinetic data suggests that only part of the particles in actually active in polymerization (N*p). N*p can be estimated assuming that the average number of radical per particle, ñ remains close to 0,5 - as found in a previous study - which gives also an estimate of very tiny particles generated at low conversion and undetectable by the usual QELS and MET techniques. The experimental data, to some extent, allow to quantify the competition between micellar and homogeneous nucleation mechanisms.
    Additional Material: 15 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 641-648 
    ISSN: 0887-6266
    Keywords: polyethylene ; glass transition ; TSDC ; γ transition ; β transition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New thermally stimulated depolarization currents (TSDC) results on LLD polyethylene functionalized with diethylmaleate polar groups are precisely computer fitted with the direct signal analysis technique. It is shown that the TSDC spectrum consists, with increasing temperatures, of a sub-γ peak, a sharp γ peak, and a β and an α relaxation. The first peak is analyzed in terms of Arrhenius relaxation times, whereas the γ and β transitions could only be fitted by using Vogel-Fulcher temperature dependence for the relaxation times. The best value for To obtained from both fittings is 69.7 K. This is a quantitative proof for the identification of the γ transition as one of the dielectric manifestations of the glass-rubber transition for polyethylenes, Tg = 136.5 K, which has been discussed extensively in the literature. The β relaxation, Tgβ = 237 K, has also the expected characteristic of a glass transition; the existence of two Tgs in polyethylene could explain our results. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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