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  • 1
    Electronic Resource
    Electronic Resource
    Sediment chemistry — Infaunal community structure in a southern European estuary related to solid-phase Microtox® toxicity testing (1995)
    Springer
    Aquatic ecology 29 (1995), S. 427-436 
    Details
    ISSN: 1573-5125
    Keywords: Sediment toxicity ; bioluminescent bacteria ; sediment contamination ; macrofaunal communities ; Sado estuary ; Portugal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper presents the results from a sedimentary survey undertaken in July 1992 in the Sado estuary, western coast of Portugal. Sediment samples were taken at 14 sites, corresponding to four organic enrichment gradients, three of which are located close to harbour facilities or to industrial or urban effluent outfalls. The fourth site is located away from direct sources of anthropogenic disturbance. An integrated approach was conducted in order to study the quality status of the superficial sediments, and included 1. the analysis of sediment descriptors and contaminants (grain-size, total organic matter, heavy metals, PCBs), 2. the evaluation of toxicity, using bioluminescent bacteria and the Microtox® solid-phase protocol and 3. the study of macrofaunal communities structure and composition. Most of the sediments showed low IC50 values (high toxicity), while benthic macrofauna did not indicate community disturbance in most of the sites, nor the contaminants analysed provided explanation for the potential toxicity observed. Most of the sediments showed high fines content. A statistical significant relation between fines and IC50 values was found, indicating the sensitivity of the toxicity assessment method for granulometry. This sensitivity might explain the lack of agreement between the IC 50 values and the sediment chemistry-infaunal communities structure. The potential grain-size sensitivity was further analysed using another test sediment from which artificial samples with different sand∶fines ratios were prepared. It is concluded that extreme caution should be used when applying the solid-phase Microtox® protocol to assess the toxicity of natural sediments, covering a range of granulometry and contamination situations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02084241
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  • 2
    Electronic Resource
    Electronic Resource
    Mineralogy, geochemistry and genesis of kaolins from the Amazon region (1998)
    Springer
    Mineralium deposita 33 (1998), S. 283-297 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The kaolin deposits of the Amazon region of Brazil are of lateritic origin, modified by subsequent reduced lacustrine and/or swamp environment. They are contemporaneous with lateritic bauxites found in the same region, all formed from aluminium silicate rocks. These are principally sedimentary rocks from the Cretaceous period (Itapecuru and Alter do Chão), but also include metamorphic and felsic volcanic rocks. After erosion of the upper part of these profiles they became locally a substratum for swampy and/or lacustrine environments mostly developed over the clayey saprolitic horizon where kaolin occurs. The saprolitic horizon is made up mainly of iron-mottled kaolinite which has been subject to an intense deferrification, which has increased the kaolin brightness and thickness. The kaolins are basically made up of well-crystallized kaolinite, quartz, sometimes illite-muscovite, anatase and hematite. In certain locations, crandallite-goyazite is also present. The deposits studied differ from each other in the mineral content levels, concentration of principal elements and in trace element distribution. The greatest quantity of quartz and, consequently SiO2, is intrinsically related to the type of parent rock. Small sedimentary deposits occur in alluvial flood plains located not very far from the lateritic source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050147
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  • 3
    Electronic Resource
    Electronic Resource
    On the prediction of order in the σ phases on the basis of a sphere-packing model (1981)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 37 (1981), S. 197-200 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A theory for the order in σ phases based on the sphere-packing model of Wilson & Spooner [Acta Cryst. (1973), A29, 342-352] has been examined using a mathematical analysis. The analysis suggests that the prediction of order in these phases based on lattice-constant variations associated with variations in atomic diameter should be treated with caution, particularly where the results are at variance with experimentally determined results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S056773948100048X
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  • 4
    Electronic Resource
    Electronic Resource
    Benzodiazepine Receptors on Primary Cultures of Mouse Astrocytes (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 36 (1981), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Benzodiazepines bind to glial membranes on a single type of site, with a high affinity (KD= 5 × 10−9 M) on about 100 fmol of sites per mg protein. The number of binding sites is increased when the membranes are treated with Triton X-100. Antiepileptic drugs such as clonazepam and phenobarbital and hypnotic drugs such as Ro-11-3128 and Ro-11-6896 are able in pharmacological concentrations to displace [3H]flunitrazepam from its glial binding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1981.tb00603.x
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulations of elementary chemical processes in liquid water using combined density functional and molecular mechanics potentials. II. Charge separation processes (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 3643-3657 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new approach to carry out molecular dynamics simulations of chemical reactions in solution using combined density functional theory/molecular mechanics potentials is presented. We focus our attention on the analysis of reactive trajectories, dynamic solvent effects and transmission coefficient rather than on the evaluation of free energy which is another important topic that will be examined elsewhere. In a previous paper we have described the generalities of this hybrid molecular dynamics method and it has been employed to investigate low energy barrier proton transfer process in water. The study of processes with activation energies larger than a few kT requires the use of specific techniques adapted to "rare events" simulations. We describe here a method that consists in the simulation of short trajectories starting from an equilibrated transition state in solution, the structure of which has been approximately established. This calculation is particularly efficient when carried out with parallel computers since the study of a reactive process is decomposed in a set of short time trajectories that are completely independent. The procedure is close to that used by other authors in the context of classical molecular dynamics but present the advantage of describing the chemical system with rigorous quantum mechanical calculations. It is illustrated through the study of the first reaction step in electrophilic bromination of ethylene in water. This elementary process is representative of many charge separation reactions for which static and dynamic solvent effects play a fundamental role. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473458
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  • 6
    Electronic Resource
    Electronic Resource
    Local magnetization and hyperfine field systematics of s−p and noble impurities in Gd and Ni hosts : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4215-4217 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic hyperfine data of s−p and noble impurities diluted in ferromagnetic Gd and Ni hosts are described within a simple model which is an extension on that one of Daniel and Friedel. We also include in the present model the effect of next-neighbor perturbation, due to the translational invariance break introduced by the impurity. Performing a self-consistent calculation of the local magnetic moments at the impurity site, one obtains the conduction electron polarization (CEP) hyperfine field. It is found that the model can explain the different hyperfine field trends observed in Gd and Ni hosts, e.g., a remaining negative value along the s−p series in the Gd case and a change of sign behavior in the Ni case. Period effects observed in noble impurities are also discussed and the theoretical calculations are in good agreement with available experimental data. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365124
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  • 7
    Electronic Resource
    Electronic Resource
    Application of commercial antennas to very long baseline interferometry radio astronomy (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 995-999 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Groundstation antennas located in Western Australia have been used as elements in the Southern Hemisphere very long baseline interferometry (VLBI) experiment. These commercial antennas of 27.5 and 15 m diameter provide a very economical improvement to the imaging capability of this array and the practice of using such antennas can be extended to other sites in the Southern Hemisphere in preparation for the forthcoming space-VLBI experiments. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145634
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  • 8
    Electronic Resource
    Electronic Resource
    On the local magnetic moments at X sites in XFe2 compounds: Pressure effects (X=Y, Lu, Zr, Hf) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3880-3882 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Adopting a simple model to describe the intermetallic cubic Laves phase compounds XFe2 (X=Y, Lu, Zr, Hf) we discuss the effect of an external applied pressure on the local magnetic moments at both sublattices. We assume that pressure acts on the system, modifying the widths of the sublattice bands and the spin-dependent hybridization between d states of the two sublattices. Using realistic densities of states we obtain, in a self-consistent way, the local d-magnetic moments at X and Fe sites which turn out to be antiparallel. As pressure increases one shows that the magnitude of the local magnetic moment at the X site increases until saturating, whereas the local magnetic moment at the Fe site decreases until saturating. Similarly to the experimental data, which show that the hyperfine field at the X site increases with applied pressure, our theoretical model predicts that the magnetic moment at the X site also increases with pressure. The calculated hyperfine and magnetic moments at the Fe site are also consistent with available experimental data. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365054
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  • 9
    Electronic Resource
    Electronic Resource
    Theoretical study of hyperfine fields at impurity nuclei in GdX (X=Zn,Cd) compounds: A two-center model : The 7th joint MMM-intermag conference on magnetism and magnetic materials (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 6971-6973 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We theoretically discuss the local moment formation and the hyperfine field behavior of nonmagnetic (s−p and noble) impurities diluted in ferromagnetic rare-earth compounds GdX (X=Zn, Cd). It is experimentally observed in these systems that all impurities enter substitutionally at the "nonmagnetic" X lattice site, creating a strong local charge perturbation. In our simplified model, one calculates the local magnetic moment in the perturbed conduction band at the origin (a charge perturbed X site). The polarization of the conduction band arises from the Gd 4f moments and the conduction electron polarization produced by the host magnetic moment at the origin is treated within the Born approximation. The general trend of the experimental hyperfine field data is well reproduced by our self-consistent calculations. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367747
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  • 10
    Electronic Resource
    Electronic Resource
    ADRENALINE SYNTHESIZING NERVE CELLS IN THE MEDULLA OF NORMOTENSIVE AND HYPERTENSIVE RATS (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 8 (1981), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. We have studied the number and distribution of adrenaline synthesizing nerve cells in the medulla oblongata of the rat, using a combination of immunofluorescence to visualize the enzyme phenylethanolamine-N-methyltransferase (PNMT) and catecholamine fluorescence to detect central catecholamines.2. The distribution of adrenaline synthesizing nerve cells was similar in normo-tensive (Wistar Kyoto) rats, spontaneous hypertensive rats, and stroke-prone rats. Few of the cells visualized by PNMT immunofluorescence were detected by the Faglu fluorescence method for catecholamines. The CI (ventrolateral) and C2 (dorsomedial) groups of PNMT cells were anatomically distinct from the Al and A2 groups of catecholamine fluorescent cells and lay rostral to these cells within the medulla. There was a third group of adrenaline synthesizing cells close to the midline in the rostral medulla, and we have called this the C3 group.3. There was a 32% increase in the number of PNMT cells in the medulla of 4-week-old stroke-prone rats.4. PNMT enzyme activity in a cross-segment of the medulla containing the adrenaline synthesizing cells was also increased by 30% in both spontaneous hypertensive rats and stroke-prone rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1981.tb00749.x
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