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  • 1
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An experiment to synthesize element 109 is presented. Decay patterns characteristic of complete fusion products were searched for in an irradiation of209Bi targets with58Fe projectiles at specific incident energies of 4.95, 5.05, and 5.15 MeV/u. A total dose of 7 ×1017 particles was obtained. The experimental method involves in-flight separation of forward peaked reaction products with a static-field velocity filter, their passage through a time-of-flight device and their final implantation into position sensitive solid state detectors to measure their kinetic energy, approximate mass and their time and position of incidence. The subsequent decay of the narrowly localised reaction products by cascades of alpha particles and/or spontaneous fission is also registered in terms of the energies and times of all the emitted particles. One outstanding decay sequence that started with the emission of two alpha particles within subsequent time intervals of 5 ms and 22 ms and ended with spontaneous fission after 13 s was found at 5.15 MeV/u. The first alpha particle had a kinetic energy of (11.10±0.04) MeV. A detailed analysis of all the alternative interpretations of this observation, such as a purely random correlation of signals, the decay of a product from a transfer reaction or of any of the various energetically possible evaporation residues, shows that the isotope with mass 266 of element 109, i.e. the one neutron evaporation channel after complete fusion, is the statistically most significant assignment. The outlook for new element synthesis is also briefly discussed.
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  • 2
    ISSN: 1432-1432
    Keywords: Key words: Spectral tuning — Photopigments — Amino acid change — Color vision — New World monkeys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Although most New World monkeys have only one X-linked photopigment locus, many species have three polymorphic alleles at the locus. The three alleles in the squirrel monkey and capuchin have spectral peaks near 562, 550, and 535 nm, respectively, and the three alleles in the marmoset and tamarin have spectral peaks near 562, 556, and 543 nm, respectively. To determine the amino acids responsible for the spectral sensitivity differences among these pigment variants, we sequenced all exons of the three alleles in each of these four species. From the deduced amino acid sequences and the spectral peak information and from previous studies of the spectral tuning of X-linked pigments in humans and New World monkeys, we estimated that the Ala → Ser, Ile → Phe, Gly → Ser, Phe → Tyr, and Ala → Tyr substitutions at residue positions 180, 229, 233, 277, and 285, respectively, cause spectral shifts of about 5, −2, −1, 8, and 15 nm. On the other hand, the substitutions His → Tyr, Met → Val or Leu, and Ala → Tyr at positions 116, 275, and 276, respectively, have no discernible spectral tuning effect, though residues 275 and 276 are inside the transmembrane domains. Many substitutions between Val and Ile or between Val and Ala have occurred in the transmembrane domains among the New World monkey pigment variants but apparently have no effect on spectral tuning. Our study suggests that, in addition to amino acid changes involving a hydroxyl group, large changes in residue size can also cause a spectral shift in a visual pigment.
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  • 3
    ISSN: 1432-1432
    Keywords: Primates ; Strepsirhines ; Aye-aye ; Lemurs ; Phylogeny ; ε-globin gene ; Molecular evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic relationships among various primate groups were examined based on sequences of ε-globin genes. ε-globin genes were sequenced from five species of strepsirhine primates. These sequences were aligned and compared with other known primate ε-globin sequences, including data from two additional strepsirhine species, one species of tarsier, 19 species of New World monkeys (representing all extant genera), and five species of catarrhines. In addition, a 2-kb segment upstream of the ε-globin gene was sequenced in two of the five strepsirhines examined. This upstream sequence was aligned with five other species of primates for which data are available in this segment. Domestic rabbit and goat were used as outgroups. This analysis supports the monophyly of order Primates but does not support the traditional prosimian grouping of tarsiers, lorisoids, and lemuroids; rather it supports the sister grouping of tarsiers and anthropoids into Haplorhini and the sister grouping of lorisoids and lemuroids into Strepsirhini. The mouse lemur (Microcebus murinus) and dwarf lemur (Cheirogaleus medius) appear to be most closely related to each other, forming a clade with the lemuroids, and are probably not closely related to the lorisoids, as suggested by some morphological studies. Analysis of the ε-globin data supports the hypothesis that the aye-aye (Daubentonia madagascariensis) shares a sister-group relationship with other Malagasy strepsirhines (all being classified as lemuroids). Relationships among ceboids agree with findings from a previous ε-globin study in which fewer outgroup taxa were employed. Rates of molecular evolution were higher in lorisoids than in lemuroids.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 8 (1967), S. 138-154 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Wirkung verschiedener Gewebe-Fixierungsmittel auf Humanalbumin und die Proteine des Seretins® (menschliche Serumkonserve) wurde papierelektrophoretisch untersucht. A. Humanalbumin. 1. In nur wenigen Fällen kommt es als Primärwirkung der Fixierungslösungen zu einer Präzipitatbildung. Für alle untersuchten Fixierungsmittel gilt, daß der größere Teil des eingesetzten Humanalbumins nach kurzem Einwirken der Fixierungslösungen als natives Eiweiß wiedergefunden wird. Nur geringe Anteile des Humanalbumins werden in wenigen Fällen durch das betreffende Fixierungsmittel denaturiert. 2. Fünfstündige Einwirkungsdauer von 5% TCE in 6% igem Formol auf das Humanalbumin hat keine verstärkte Wirkung zur Folge. 3. Die Wirkung von 6% igem Glutardialdehyd auf das Humanalbumin ist streng zeitabhängig. Bereits 10 min nach Zugabe des Glutardialdehyds zum Humanalbumin enthält die Lösung kein natives Eiweiß mehr. B. Seretin ® . 1. Nach ihrer Wirkung auf das Seretin® lassen sich die untersuchten Fixierungsmittel in drei Gruppen gliedern: a) Fixierungsmittel mit sehr geringer Wirkung. Die Eiweiße des Seretins® werden durch diese Fixierungsmittel nicht oder kaum vermindert. Nur geringe Eiweißmengen werden denaturiert. Diese Fixierungsmittel wirken auch bei fortschreitender Einwirkungszeit nicht stärker. Zu der Gruppe gehören: Methanol 96%, Osmiumtetroxyd 2% und Formol 10%. b) Fixierungsmittel mit geringer bis stärkerer Wirkung. Meist kommt es nach Zusatz dieser Mittel zur Präzipitatbildung. Teilweise enthalten die Niederschläge aber noch beträchtliche Mengen nativen Eiweißes. Natives Protein wird in jedem Fall gefunden. Denaturiertes Eiweiß liegt in mittleren bis größeren Mengen vor. Die Wirkung dieser Fixierungsmittel ist nur wenig zeitabhängig. Geordnet nach steigender Wirksamkeit handelt es sich um folgende Mittel: TCE 10%, Äthanol 96%, 0,5% TCE in 6% igem Formol, Gemisch nach Carnoy, Perchlorsäure 2%, Gemisch nach Bouin und 5% TCE in 6% igem Formol, c) Stark wirkende Fixierungsmittel. Stets Präzipitat-oder Gelbildung. Weder die Überstände noch die Niederschläge enthalten nach dreistündiger Versuchsdauer noch natives Eiweiß. Die Proteine sind quantitativ denaturiert. Die Wirkung dieser Mittel verstärkt sich mit fortschreitender Einwirkungsdauer. Es handelt sich um die Lösung Susa nach Heidenhain und das Gemisch nach Stieve sowie um Glutardialdehyd 2% und 6%. — 2. Bei der Einwirkung von 0,5% TCE in 6% igem Formol auf das Seretin® konnte zwischen 0 und 37° C keine Temperaturabhängigkeit der Wirkung gefunden werden. — 3. 5% TCE in 6% igem Formol wirkt mit steigender Temperatur zunehmend stärker denaturierend auf die Seretineiweiße ein. Während bei einer Versuchstemperatur von 0° C nach 3 Std noch größere Mengen nativen Eiweißes wiedergefunden wurden, enthielt die Lösung bei einer Versuchstemperatur von 37° C nach dieser Zeit nur noch denaturiertes Eiweiß. Es scheint hier aber auch schon zu einer Eiweißhydrolyse zu kommen.
    Notes: Summary The influence of various tissue fixatives on human albumin and the proteins of Seretin® (bottled human serum) is tested by means of electrophoresis. A. Human Albumin. 1. Only in a few cases the formation of a precipitate is the first reaction to a treatment with fixatives. All fixatives tested show, that if the treatment lasts for only a short period, the major part of the human albumin treated with fixative is recovered as native protein. In a few cases a small quantity of the human albumin is denatured by the respective fixative. — 2. Treating human albumin with 5% trichloracetic acid (TCE) in 6% formalin for 5 hours shows no increased effect. — 3. The action of 6% glutardialdehyde on human albumin is strictly time-dependent. 10 minutes after glutardialdehyde is added to human albumin no native protein is demonstrable in the solution. B. Seretin ® . 1. According to their action on Seretin the fixatives in question can be divided in three groups: a) Fixatives which have very little effect. The proteins of Seretin® are little or not at all affected by the action of the fixative. Only very small quantities of protein are denatured. The effect of these fixatives does not increase with increasing time. The group includes: Methanol 96%, osmiumtetroxyd 2%, and formalin 10%. b) Fixatives with slight to stronger effects. In most cases a precipitate will form after the fixative has been added to the protein solution. Some of the precipitates, however, contain considerable amounts of native protein. Native protein is demonstrable in any case. Denatured protein is demonstrable in medium to large amounts. The effect of these fixatives is hardly influenced by time. In order of increasing effect the fixatives in question are: TCE 10%, ethanol 96%, 0,5% TCE in 6% formalin, Carnoy's solution, perchloric acid 2%, Bouin's solution, and 5% TCE in 6 % formalin. c) Fixatives with strong effects. They regularly induce the formation of either a precipitate or a gel. After three hours neither supernates nor precipitates contain any native protein. The proteins are qualitatively denatured. The effect of the fixatives increases with the time of treatment. The fixatives in question are: Susa solution (Heidenhain), Stieve's solution, glutardialdehyde 2% and 6%. — 2. Temperatures between 0° C and 37° C have no influence on the effect of 0,5 % TCE in 6% formalin on Seretin. — 3. With rising temperatures 5% TCE in 6% formalin has an increasing denaturing effect on the proteins of Seretin®. While larger quantities of native protein are found after 3 hours a t0° C, only denatured proteins are demonstrable after the same period of time at 37°. It seems, however, that in this case too a protein hydrolysis takes place.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 4 (1964), S. 348-350 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 6
    ISSN: 1573-4927
    Keywords: MARMOSETS ; TAMARINS ; CALLITRICHINI ; POLYMORPHISM ; GENETIC DISTANCE ; GENETIC VARIABILITY
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Five hundred forty-three blood samples from 15populations of the four genera of callitrichin primateswere studied electrophoretically. Polymorphism andgenetic distances were estimated for 20 loci, 13 of which were polymorphic. The lion tamarin(Leontopithecus) studied here exhibited theleast variability for these loci, while the monospecificCebuella showed the most. The genetic distancesobserved between Callithrix andCebuella genera support previous evidenceindicating a close taxonomic relationship between them.Genetic distance values obtained in this study alsosupport the synonimization of the kuhli form with Callithrix jacchuspenicillata.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of computer aided molecular design 14 (2000), S. 487-494 
    ISSN: 1573-4951
    Keywords: de novo design ; diversity ; docking ; genetic algorithm ; peptide mimetic ; pharmacophore ; similarity ; thrombin ; virtual screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An evolutionary algorithm was developed for fragment-based de novo design of molecules (TOPAS, TOPology-Assigning System). This stochastic method aims at generating a novel molecular structure mimicking a template structure. A set of ∼25,000 fragment structures serves as the building block supply, which were obtained by a straightforward fragmentation procedure applied to 36,000 known drugs. Eleven reaction schemes were implemented for both fragmentation and building block assembly. This combination of drug-derived building blocks and a restricted set of reaction schemes proved to be a key for the automatic development of novel, synthetically tractable structures. In a cyclic optimization process, molecular architectures were generated from a parent structure by virtual synthesis, and the best structure of a generation was selected as the parent for the subsequent TOPAS cycle. Similarity measures were used to define `fitness', based on 2D-structural similarity or topological pharmacophore distance between the template molecule and the variants. The concept of varying library `diversity' during a design process was consequently implemented by using adaptive variant distributions. The efficiency of the design algorithm was demonstrated for the de novo construction of potential thrombin inhibitors mimicking peptide and non-peptide template structures.
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  • 8
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. MaleDanaus chrysippus butterflies the larvae of which have been raised indoors on their natural foodplants (Asclepias) lack the pyrrolizidinone pheromone (Fig. 1, I) which is known from the hairpencils of field-caught butterflies. 2. MaleD. chrysippus have been observed actively approaching withered parts of aHeliotropium plant in Kenya. These observations could be repeated in the laboratory. On the plants, the males suck extensively. 3. A pyrrolizidine alkaloid (Fig. 1, II) has been isolated and characterized as lycopsamine from thisHeliotropium species. 4. Significant and up to “normal” amounts of I are found in the hairpencils after the indoors-raised males were allowed to: a) suck on withered and remoistenedHeliotropium, or b) feed on a methanol extract ofHeliotropium, or c) feed on a solution of alkaloid (II) isolated fromHeliotropium (see Table 1, Fig. 2). It therefore appears that substance II is a dietary precursor of I. 5. Electroantennogram recordings revealed the presence of antennal olfactory receptors for both substances I and II, as well as for the odor of the withered and remoistenedHeliotropium (Fig. 3). 6. Experiments in which radiolabelled compounds were administered toD. gilippus berenice males also suggest that the pyrrolizidine pheromone (I) is biosynthesized from an exogenous alkaloid precursor.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 9 (1972), S. 127-140 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Adsorption isotherms of water on human red cell membranes have been measured and the results used to determine the Brunauer-Emmett-Teller monolayer coverage, saturation hydration, and relevant heats and entropies of hydration. The tightly bound monolayer corresponds to a complete covering of only one membrane surface and the saturation hydration is greater than values for globular proteins and phospholipids. A hysteresis loop is observed in the adsorption-desorption cycle. Circular dichroism spectra of membrane films have been measured as a function of hydration in the ultraviolet region of the spectrum. The spectra resemble those of membrane suspensions with reduced scattering. The circular dichroism did not change upon dehydration of the membrane films from 92 to 0% relative humidities, implying a stable membrane protein structure independent of both water content and lipid phase.
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  • 10
    ISSN: 1573-8604
    Keywords: IRBP intron 1 DNA sequences ; ceboid phylogenetic systematics ; Callithrix pygmaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We determined DNA sequences spanning the 1.8-kb long intron 1 of the interstitial retinol-binding protein nuclear gene (IRBP) for Callithrix geoffroyi, Callithrix humeralifer, and Callithrix argentata. With the 22 previously determined IRBP intron 1 sequences—21 from the 16 currently recognized genera of New World monkeys—the enlarged IRBP data represent for the marmoset genus Callithrix both its argentata and its jacchus species groups. Maximum-parsimony and neighbor-joining trees, constructed for the 25 aligned IRBP intron 1 sequences, support a provisional phylogenetic classification with three families: Atelidae, containing subfamily Atelinae; Pitheciidae, containing subfamily Pitheciinae; and Cebidae, containing subfamilies Cebinae, Aotinae, and Callitrichinae. In order to have taxa at the same hierarchical rank at equivalent age, this classification has all living callitrichines in a single tribe, Callitrichini, with four subtribes: Saguinina (Saguinus), Callimiconina (Callimico), Leontopithecina (Leontopithecus), and Callitrichina (Callithrix with the pygmy marmoset, Cebuella pygmaea, merged into it). The DNA evidence shows not only that Callithrix must include C. pygmaea to be monophyletic but also that the times of separation of pygmaea and the argentata and jacchus species groups from one another are to be expected (〈5 Ma—million years ago) for species in a single genus. On relating the time course of the ceboid radiation to biogeographic information, it appears that in mid-Miocene times (10–11 Ma) a basal callitrichin stock branched into the ancestral population of Saguinus in one clade and the ancestral population of Leontopithecus and Callimico–Callithrix (or Leontopithecus–Callimico and Callithrix) in another clade. The proto-lion tamarins migrated south and eastward, where they were isolated in refugia, becoming the genus Leontopithecus. The stock remaining in Amazonia gave rise to present-day Callimico and Callithrix. The latter genus occupied a vast geographic area, giving rise to the argentata and pygmaea groups in Amazonia and to the jacchus group in central and eastern Brazil.
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