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  • 2000-2004  (8)
  • 1965-1969  (1)
  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have constructed a liquid He free SC-ECRIS and successfully extracted intense beams of various heavy ions. To improve its performance, we installed a negatively biased electrode in the plasma chamber and observed its effect on the beam intensity systematically. We measured the beam intensity and the current of biased electrode as a function of both the applied bias voltage and the electrode position. Using the negatively biased electrode, the beam intensity of highly charged Xe ions was strongly enhanced. Furthermore, both the beam intensity and the current of biased electrode oscillated strongly. The frequency became higher when increasing the magnitude of bias voltage. This result shows that the biased electrode causes a certain instability in the electron cyclotron resonance plasma, so that the beam intensity is enhanced. In this contribution, we present the results of our experiment and the discussions about possible mechanisms of such instability. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The nitrogen metabolism and excretion patterns of the grunting toadfish Allenbatrachus grunniens and the effects of salinity on these processes were examined. Individuals of A. grunniens were subjected to several experimental treatments, including variable salinity (2 to 30), high pH (8·5 compared to 7·0 for controls), high environmental ammonia (10 mM) and confinement to small water volumes, and measurements were made of activities of selected enzymes of nitrogen metabolism, ammonia and urea excretion rates, and tissue and plasma contents of ammonia, urea and amino acids. Activities of key ornithine-urea cycle enzymes were rather low (e.g. liver carbamoyl phosphate synthetase III activity was 0·001 μmols min−1 g−1), and A. grunniens consistently demonstrated a low capacity for urea excretion despite significant elevations of plasma and tissue ammonia contents by the high pH and high ammonia treatments. This species could thus be categorized as ammoniotelic. Total free amino acid contents in plasma and tissues were increased by the high pH and high ammonia treatments, but no patterns were discerned in individual amino acids that would indicate any preferential accumulation (e.g. alanine and glutamine) as has been noted previously in several semi-terrestrial fish species. Thus, it appeared that A. grunniens was not unusual in its patterns of nitrogen metabolism and excretion in comparison to other ‘typical’ teleosts. Furthermore, manipulation of salinity had no major effects on nitrogen excretion in either this species or in comparative studies with the ureotelic gulf toadfish Opsanus beta. The results are discussed in the context of the broader pattern of nitrogen metabolism and excretion in the Batrachoididae.
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 446-453 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ti bulk diffusion coefficients have been determined for Ti in single crystal MgO(100) for four types of samples: Ti evaporated onto MgO and Ti evaporated onto MgO that was pre-bombarded with 7 keV Cl+, Ar+, and Cr+, respectively. Diffusion was induced by annealing to 1000 °C following the evaporation or pre-bombardment. Diffusion penetration profiles were obtained by using secondary ion mass spectrometry depth profiling techniques. A model that includes a depth-dependent bulk diffusion coefficient was used to analyze the observed radiation enhanced diffusion (RED) effects. The bulk diffusion coefficients are of the order of 10−20 m2/s and are enhanced due to the defect structure inflected by the ion pre-bombardment. Different RED effects for the samples pre-bombarded with Cl+, Ar+, and Cr+ were observed despite their very similar ballistic implantation parameters. The diffusion model was extended to include the effects of lattice deformation, requirement of electrical neutrality, and chemical effects such as volatile compound formation. This extended model satisfactorily explains the RED differences observed for Cl+, Ar+, and Cr+ implantation. Our results show that RED is strongly influenced by the chemical properties of implanted ions. © 2001 American Institute of Physics.
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: There is growing evidence of the brain's ability to increase its reliance on alternative metabolic substrates under conditions of energy stress such as starvation, hypoxia and ischemia. We hypothesized that following traumatic brain injury (TBI), which results in immediate changes in energy metabolism, the adult brain increases uptake and oxidation of the alternative substrate β-hydroxybutyrate (βHB). Arterio-venous differences were used to determine global cerebral uptake of βHB and production of 14CO2 from [14C]3-βHB 3 h after controlled cortical impact (CCI) injury. Quantitative bioluminescence was used to assess regional changes in ATP concentration. As expected, adult sham and CCI animals with only endogenously available βHB showed no significant increase in cerebral uptake of βHB or 14CO2 production. Increasing arterial βHB concentrations 2.9-fold with 3 h of βHB infusion failed to increase cerebral uptake of βHB or 14CO2 production in adult sham animals. Only CCI animals that received a 3-h βHB infusion showed an 8.5-fold increase in cerebral uptake of βHB and greater than 10.7-fold increase in 14CO2 production relative to sham βHB-infused animals. The TBI-induced 20% decrease in ipsilateral cortical ATP concentration was alleviated by 3 h of βHB infusion beginning immediately after CCI injury.
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  • 6
    ISSN: 1569-8041
    Keywords: high dose ; Hodgkin's lymphoma ; patterns ; relapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background:High-dose chemotherapy has an established role inrecurrent or refractory Hodgkin's lymphoma (HL) although a significantproportion of patients subsequently relapse. This manuscript describes theclinical characteristics of such patients and documents their furthermanagement at two major UK cancer centres. Patients and methods:Between 1987 and 1996 one hundred patientswith recurrent or refractory HL received high-dose chemotherapy (HDCT) withautologous haematopoietic rescue. All had recurred within 12 months of initialtherapy or had two or more recurrences. Results:With a median follow-up of 2 years, 56 patients arecurrently progression-free. There were six treatment-related deaths. Onepatient died of pneumonia in remission. Thirty-seven patients have relapsed,intrapulmonary disease being seen for the first time in 53% andrecurrence at previous sites of disease in 81%. Following recurrence,therapy was determined by circumstances: either one agent at a time was used(single sequential approach) or multiagent chemotherapy was chosen. There wasa survival advantage for those who achieved a symptomatic response (13 vs. 4months median, P = 0.0001). A trend towards longer survival was seenfor those whose disease recurred beyond six months following high-dosechemotherapy and in those who received combination chemotherapy. Conclusions:These results confirm that HDCT with autologoushaematopoietic support is inadequate for about half the patients who receiveit for high-risk HL. Relapse in the site of prior disease is the most likelypattern with intrapulmonary disease for the first time occurring frequently.It is possible to administer further chemotherapy after failure of HDCT, andboth objective as well as subjective benefit can be achieved. A few patientsappear to get long-term benefit from further treatment.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 1899-1910 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The circulating flows formed inside a spherical drop under time-periodic nonuniform electric fields are considered. For simplicity, it is assumed that there are axisymmetric electric fields and that the flow fields are in the Stokes flow regime. An analytical solution of the streamfunction distribution inside and outside the drop is obtained. The flow field is found to be dependent on the frequency of the time-periodic electric field and the ratios of the material properties such as the viscosity, the electrical conductivity, and the electrical permittivity. As part of the solution, an analytical expression of the dielectrophoretic migration velocity of a drop under a time-periodic electric field is also obtained. The result shows an interesting physics—that dielectrophoretic migration is possible in a time-periodic electric field even in the situation where dielectrophoresis would be impossible in a static electric field. By using the analytical solution of the streamfunction, fluid mixing inside a drop is analyzed based on the Poincaré maps. The mass transfer enhancement factor due to fluid mixing has also been computed by solving the unsteady mass transfer equation numerically. The existence of an optimal frequency has been confirmed as in other mass transfer enhancement processes by time-periodic forcing. © 2000 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 5058-5064 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Titanium bulk and dislocation diffusion coefficients at 1000 °C have been determined for Ti in single crystal α-Al2O3(0001) for three types of samples: (i) Ti evaporated onto Al2O3, (ii) 48Ti+at 100 eV deposited onto Al2O3, and (iii) 48Ti+ at 100 eV deposited onto radiation damaged Al2O3 (damage inflected by implantation of 46Ti+ at 7 keV). Diffusion penetration profiles were obtained by using secondary ion mass spectrometry depth profiling techniques. For the deposited and implanted Ti+ samples, the bulk diffusion coefficients (D) are 5.4×10−21 and 5.6×10−17 m2 s−1, respectively, and dislocation diffusion coefficients are 3.6×10−17 and 1.4×10−12 m2 s−1, respectively. Comparing the D's for Ti in the undamaged and damaged Al2O3, the D's for the latter samples are higher by a factor of 104–105, reflecting the radiation enhanced diffusion due to the defect structure inflected by the implanted 7 keV 46Ti+. Comparing the D's for Ti deposited onto Al2O3 (both the evaporated and 100 eV 48Ti+ samples) with those for Cr deposited onto Al2O3, the Ti D's are larger by a factor of 10, reflecting the influence of the valence state of the cation. These results show that cationic diffusion coefficients in Al2O3 can be controlled by varying the level of defects in the crystal. © 2000 American Institute of Physics.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 1431-1435 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Efforts to prepare 1,6-dicyano-2,4-hexadiyne resulted in the formation of insoluble, chemically inert, high-melting “brick dust” type polymeric materials. Similar appearing products arose from the dihalo-, ditosyl-, and dihydroxy- hexadiyne derivatives as well as propargyl halide starting materials. It appears that diacetylenic diols and their propargylic precursors undergo direct nitrilation.
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