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  • 1
    ISSN: 1615-6102
    Keywords: Xylem pressure probe ; Turgor pressure probe ; Xylem osmotic pressure ; Diurnal changes ; Liana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Long-term xylem pressure measurements were performed on the lianaTetrastigma voinierianum (grown in a tropical greenhouse) between heights of 1 m and 9.5 m during the summer and autumn seasons with the xylem pressure probe. Simultaneously, the light intensity, the temperature, and the relative humidity were recorded at the measuring points. Parallel to the xylem pressure measurements, the diurnal changes in the cell turgor and the osmotic pressure of leaf cells at heights of 1 m and 5 m (partly also at a height of 9.5 m) were recorded. The results showed that tensions (and height-varying tension gradients) developed during the day time in the vessels mainly due to an increase in the local light intensity (at a maximum 0.4 MPa). The decrease of the local xylem pressure from positive, subatmospheric or slightly above-atmospheric values (established during the night) to negative values after daybreak was associated with an almost 1 ∶ 1 decrease in the cell turgor pressure of the mesophyll cells (on average from about 0.4 to 0.5 MPa down to 0.08 MPa). Similarly, in the afternoon the increase of the xylem pressure towards more positive values correlated with an increase in the cell turgor pressure (ratio of about 1 ∶ 1). The cell osmotic pressure remained nearly constant during the day and was about 0.75–0.85 MPa between 1 m and 9.5 m (within the limits of accuracy). These findings indicate that the turgor pressure primarily determines the corresponding pressure in the vessels (and vice versa) due to the tight hydraulic connection and thus due to the water equilibrium between both compartments. An increase in the transpiration rate (due to an increase in light intensity) results in very rapid establishment of a new equilibrium state by an equivalent decrease in the xylem and cell turgor pressure. From the xylem, cell turgor, and cell osmotic pressure data the osmotic pressure (or more accurately the water activity) of the xylem sap was calculated to be about 0.35–0.45 MPa; this value was apparently not subject to diurnal changes. Considering that the xylem pressure is determined by the turgor pressure (and vice versa), the xylem pressure of the liana could not drop to — in agreement with the experimental results — less than -0.4 MPa, because this pressure corresponds to zero turgor pressure.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic investigation of the structure and magnetic properties of novel compounds Tb3(Fe1−xVx)29 (x=0.033, 0.044, 0.056, and 0.061) has been performed. The lattice parameters and Curie temperatures are obtained. The saturation magnetization of Tb3(Fe1−xVx)29 decreases but the anisotropy field increases linearly with increasing V concentration at 4.2 K and room temperature. The spin reorientations of the easy magnetization direction of Tb3(Fe1−xVx)29 occur at around 160 K. A first order magnetization process of Tb3(Fe1−xVx)29 is observed with magnetic field in the range between 2.0 and 1.6 T at room temperature. The saturation magnetization of Tb3Fe29−yVy with a low V concentration at 4.2 K can be roughly calculated based on a combination of that of the Tb2Fe17 and TbFe12−yVy units in a ratio of 1:1. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using the57Fe Mössbauer effect the influence of the Ga content in amorphous (Fe1−x Ga x )84B16 on the average hyperfine fields $$\bar H$$ and isomer shift has been studied. For the sample (Fe0.98Ga0.02)84B16 the $$\bar H$$ , as well as the recoilless fraction,f a were measured as functions of temperature ranging from 12 K to 300 K. The experimental results show a linear correlation between Inf a and δ, and well as between δ andx. In the temperature range $$\bar H(T)$$ can be described by the Brillouin function and the second-order Doppler shift is appreciable. The characteristic temperature for such an amorphous alloy is 372 K. the effective vibrating massM eff=79 a.u.
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  • 4
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic properties of Sm2(Fe1−xGax)17 compounds and their nitrides have been studied. Substitution of Ga for Fe leads to an increase in lattice constants. Introduction of nitrogen results in a further increase in lattice constants. Substitution of Ga for Fe causes a dramatic change of the Curie temperature of the Sm2(Fe1−xGax)17 compounds. When x=0.2 the Curie temperature is enhanced by about 200 K. X-ray-diffraction patterns of aligned samples of Sm2(Fe1−xGax)17 compounds show that alloys with x=0.15, 0.20, and 0.25 exhibit uniaxial anisotropy at room temperature. The introduction of nitrogen made the samples with x≤0.4 exhibit uniaxial anisotropy at room temperature. The Curie temperature of the nitrides decreases with the Ga concentration. The anisotropy fields of the nitrides derived from the high-field magnetization. The changes of the magnetic anisotropy, saturation magnetization, and the moment of the Fe atoms in the nitrides and their parent compounds with Ga concentration are discussed.
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  • 6
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The absolute pressure in conducting xylem vessels of roots of 2-week-old, slowly transpiring intact maize plants (bathed in nutrition medium) was determined to be +0·024 ± 0·044 MPa using the xylem pressure probe. When the roots were subjected to osmotic stress (NaCI, KCI or sucrose), the xylem pressure decreased immediately and became more negative. However, the response of xylem pressure to osmotic stress was considerably attenuated, indicating that the radial reflection coefficients, σ13 of the maize root for these solutes were rather low (between 0·2 and 0·4 depending on the concentration of the osmoticum). The low values of a, may be caused (partly) by unstirred layer effects. In repeated osmoticum/nutrition regimes a complex pattern of changes in xylem pressure was observed which was apparently linked to the interplay between transpiration and (passive and/or active) solute loading of the xylem. These processes were not observed when the roots were subjected to osmotic stress after excision. In this case, a biphasic response was observed comparable to that found for excised roots using the root pressure probe.
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  • 7
    Publication Date: 2018-10-02
    Description: Purpose: Toca 511 is a gammaretroviral replicating vector encoding cytosine deaminase that selectively infects tumor cells and converts the antifungal drug 5-fluorocytosine into the antineoplastic drug 5-fluorouracil, which directly kills tumor cells and stimulates antitumor immune responses. As part of clinical monitoring of phase I clinical trials in recurrent high-grade glioma, we have performed extensive molecular analyses of patient specimens to track vector fate. Patients and Methods: Toca 511 and Toca FC (extended-release 5-fluorocytosine) have been administered to 127 high-grade glioma patients across three phase I studies. We measured Toca 511 RNA and DNA levels in available body fluids and tumor samples from patients to assess tumor specificity. We mapped Toca 511 integration sites and sequenced integrated Toca 511 genomes from patient samples with detectable virus. We measured Toca 511 levels in a diverse set of tissue samples from one patient. Results: Integrated Toca 511 is commonly detected in tumor samples and is only transiently detected in blood in a small fraction of patients. There was no believable evidence for clonal expansion of cells with integrated Toca 511 DNA, or preferential retrieval of integration sites near oncogenes. Toca 511 sequence profiles suggest most mutations are caused by APOBEC cytidine deaminases acting during reverse transcription. Tissue samples from a single whole-body autopsy affirm Toca 511 tumor selectivity. Conclusions: Toca 511 and Toca FC treatment was not associated with inappropriate integration sites and clonal expansion. The vector is tumor-selective and persistent in patients who received Toca 511 injections. Clin Cancer Res; 24(19); 4680–93. ©2018 AACR .
    Print ISSN: 1078-0432
    Electronic ISSN: 1557-3265
    Topics: Medicine
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