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  • 1
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Autoradiography at different levels of resolution was used to study the disposition of the polycyclic aromatic hydrocarbon benzo(a)pyrene (3H-BaP) in juvenile and sexually mature polar cod (Boreogadus saida). Exposure took place via the water or after intragastric administration at subzero temperatures. In water-exposed fish, high total tissue levels were found in the gills, olfactory organ, anterior kidney, liver, skin and intestinal wall. Only traces of radioactivity were present in the muscle, brain and gonads. No major differences in tissue levels or in general distribution pattern between males, females or juvenile fish were observed. The gills appeared to be the absorption site for exposure via water. After oral administration, tissue levels of 3H-BaP-derived radioactivity were negligible. Following both administration routes, levels of radioactivity were highest in the bile and intestinal contents while only traces were observed in the urine, indicating biliary excretion as the major excretory pathway in this aglomerular species. Tape-section autoradiography of fish exposed via water revealed tissue-bound residues of 3H-BaP in the olfactory organs, gills, kidney, liver, skin and intestinal mucosa. Light-microscopy autoradiography demonstrated that the bound residues in the olfactory organ, gills and anterior kidney were localized in epithelial cells, while those in liver and intestinal mucosa were evenly distributed. In conclusion, the present study shows that BaP is absorbed from the water via the gills at subzero temperatures, that tissue levels are considerably higher after water exposure than after dietary exposure, that biliary excretion is predominant and, finally, that site-specific tissue binding in the olfactory organs, gills and anterior kidney is confined to epithelial cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 2 (1983), S. 201-204 
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Induction of crown galls on 4–6 week old soybean (Glycine max (L.) Merr.) plants cultured in growth chambers was obtained with Agrobacterium tumefaciens strains C58, T37 and ACH5. The crown galls were isolated and cultured in vitro as sterile callus and liquid suspension cultures. Transformation was tested by opine tests and by molecular hybridization of restricted cell DNA with T-DNA fragments. Protoplasts were isolated from suspension cultures. Transformed protoplasts regenerate cell walls, divide and form calli without an exogenous supply of hormones.
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  • 3
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for plant regeneration via organogenesis in pea (Pisum sativum) using nodal thin cell layer segments has been developed. From 10 to 12 days old sterile pea seedlings, nodal expiants were excised from which leaves and axillary buds were removed. Shoot regeneration was consistently obtained from liquid cultures where the expiants were floated on the medium. Shoots could be harvested after two weeks and thereafter up to ten weeks and no important effect of the cultivar (Bodil, Puget, Rondo and Trille) used could be observed as far as shooting capacity was concerned. Rooting frequency of the regenerated shoots was cultivar dependent. Plantlets were obtained within 7 weeks after expiant excision. Agrobacterium tumefaciens carrying a disarmed Tiplasmid and a binary vector containing the ß-glucuronidase reporter gene, were used in cocultivation experiments on pea nodal expiants in order to obtain transgenic shoots.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 35 (1980), S. 21-33 
    ISSN: 0945-3245
    Keywords: AMS(MOS): 65B05 ; CR: 5.17
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary The trapezoidal rule with deferred corrections using uncentered end formulas is shown to converge. While the proof technique is more specialized than the standard asymptotic expansion approach, it has some advantages. In addition to providing a more complete theoretical justification for current implementations of deferred corrections with the trapezoidal rule, the approach given here will hopefully apply for several other discretization methods.
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  • 5
    ISSN: 1432-0630
    Keywords: 74.70 ; 81.15J ; 41.80D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Thin-film superconducting YBa2Cu3O7−x layers have been produced in a single-step process by pulsed electron beam evaporation from a stoichiometric 1-2-3 target. The films were produced at the 〈100〉 surface of SrTiO3 substrates heated to a temperature of approximately 1000 K in a pure oxygen atmosphere of about 10 Pa total pressure. After deposition the films were cooled in situ within 20 minutes to ambient temperature. At present, the films are polycrystalline and show a Tc,zero of 83 K with a transition width of 3–5 K. Critical current densities of 7·104 A/cm2 at 4.2 K and zero magnetic field have been achieved. The pulsed electron beams used in these experiments are produced by a pseudospark discharge; the estimated energy density deposited at the target surface by the electron beam is of the order of 4 J/cm2.
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  • 6
    ISSN: 1432-0630
    Keywords: 52.50 ; 52.80 ; 81.15Jj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The investigation of the interaction of pulsed electron beams with PMMA (polymethylmethacrylate) targets is reported. The electron beam of some 10−8 s in duration is produced in a pulsed low-pressure gas discharge. The beam power density of up to 108 W/cm2 leads to a surface plasma formation similar to that of the pulsed laser ablation process. The propagation of the ablated material and the shock wave inside the PMMA target are observed by means of Schlieren diagnostics. An electron density gradient of over 3×1019 cm−4 has been observed in the expanding plasma up to 1.5 μs after the plasma formation. During the early stage of expansion, the expansion velocity of the plasma plume as determined by the steep electron density gradient is around 105 cm/s. The pressure behind the shock front inside the PMMA target as determined from the shock velocity exceeds 0.3 Gpa.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 20 (1981), S. 59-64 
    ISSN: 1432-1041
    Keywords: epilepsy ; carbamazepine ; particle size ; in-vitro-dissolution rates ; clinical biopharmacy ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a biopharmaceutical study of carbamazepine, the F-CBZ, DAK preparation, which contained small particles with minor variation in size, had a more rapid dissolution rate than Tegretol, which contained larger particles of more variable size. Accordingly, carbamazepine had a more rapid absorption rate from F-CBZ, DAK than from Tegretol in a comparative absorption test involving single-dose administration of 200mg to 8 healthy volunteers. The clinical significance of the difference in absorption rates for the steady state levels of carbamazepine and carbamazepine-10,11-epoxide, and the frequency of side-effects in relation to tablet intake, were evaluated in a double-blind, randomized, double-dummy cross-over trial of 35 days' duration, in 21 well-adjusted epileptic patients. 9 patients were treated with Tegretol alone and 12 with Tegretol combined with other antiepileptic drugs. A lower steady state plasma level of carbamazepine was found at 08.00 h during treatment with F-CBZ, DAK in comparison with Tegretol. The difference was small. There was no difference in the type and frequency of side-effects or seizures between the 2 preparations. The frequency of epileptic fits was not correlated with the plasma level of carbamazepine or the epoxide. Side-effects, however, had a tendency to be correlated with the concentration of the epoxide. Thus, the particle size influenced the absorption rate of carbamazepine, without having a significant correlation with the frequency of side-effects. The difference in the minimum plasma level of carbamazepine between treatments with the two preparations was modest, and appeared to be without clinical significance.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 14 (1978), S. 47-51 
    ISSN: 1432-1041
    Keywords: Carbamazepine ; carbamazepine-10,11-expoxide ; human brain concentration ; temporal lobe epilepsy ; combined treatment ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-Epoxide) in the temporal lobe were measured in five epileptic patients undergoing unilateral temporal lobectomy. The patients had been under CBZ treatment from 6 months to 6 years and all were in steady state at the time of operation. The brain tissue concentration of CBZ in all patients was higher than the plasma concentration; the brain/plasma ratio ranged from 1.4–1.6. Brain/plasma ratios of CBZ-Epoxide ranged from 0.6–1.5. The ratio for CBZ was similar in patients treated with CBZ alone or in combination with other anticonvulsants, but for the CBZ-Epoxide a higher ratio was found in patients on combined treatment. The results may mean that other antiepileptic drugs, too, can influence the brain concentration of an active metabolite, which could have a bearing on the enhanced therapeutic effect often seen on combining CBZ treatment with other antiepileptic drugs.
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  • 9
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The quadrupole hyperfine interaction of111Cd in Cd, In, Sn, and of67Zn,69Ge in Zn was measured with high accuracy using TDPAC and TDPAD methods; in addition the systems117In in Cd and In, and113Sn in Cd were investigated. The temperature dependence of the electric field gradienteq(T) can be reproduced by the simple relationeq(T)/eq(0)=1—B⋅T 3/2 over a range of temperatures from a few K up to the melting point. A comparison with other experiments was carried out to test the universality of this empirical relation. In particular, high precision NQR experiments on Ga, In and Sb strongly support this relation. It is discussed whether lattice vibrations can explain the observed temperature variation or whether the experimental data indicate the need for a new description. Some new ideas suggesting a basically different model are given.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 261 (1973), S. 13-23 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer spectra in α-Fe2O3 were measured below and above the Morin temperature following the reaction56Fe(d, p)57Fe. Within high accuracy, shift, quadrupole splitting, and Debye-Waller-factor are found to be the same as corresponding radioactive source data, whereas the magnetic field is lower by 10 kG. It follows that 10−7 s after the nuclear reaction essentially all excited recoils are at normal lattice sites with nearest neighbors being undisturbed. The deviation in magnetic field cannot be explained by a rise in temperature.
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