Studies on the cytokinins in fruits I. Occurrence and levels of cytokinin-like substances in grape berries at different developmental stages

The occurrence and levels of cytokinin-like substances in the berries of Bangalore Blue grapes were studied at different stages of growth. The concentration of cytokinins was maximum cluring anthesis ancl the first rapid growth period. The level of cytokinins cleclined markedly cluring the lag and subsequent rapid growth phase. Two growth promoting zones were cletectecl by soybean callus bioassay in the thin layer chromatographs of berry extracts, at all stages of sampling. Although the identity of cytokinin-like substances has not been establishecl, the present study supports the hypothesis that besides auxins, gibberellins, abscisic acid and ethylene, cytokinins are also involvecl in the growth and development of grape berries.Untersuchungen über die Cytokinine in FrüchtenI. Vorkommen und Gehalt cytokininartiger Substanzen in Traubenbeeren verschiedenen EntwicklungszustandesIn verschiedenen Entwicklungsstadien der Beeren von Bangalore Blue wurden das Auftreten und die Menge cytokininartiger Substanzen untersucht. Die Cytokininkonzentration war während der Anthese und der ersten Phase raschen Wachstums am höchsten. Während der anschließenden Phase verlangsamten Wachstums und der darauf folgenden Phase erneuten starken Wachstums fiel die Cytokininkonzentration deutlich ab. Mit Hilfe des Sojabohnenkallus-Tests wurden auf den Dünnschichtchromatogrammen von Beerenextrakten aller Entwicklungsstadien zwei wachstumsfördernde Zonen nachgewiesen. Obgleich die cytokininartigen Substanzen nicht identifiziert wurden, wird durch die vorliegende Untersuchung doch die Hypothese gestützt, daß neben Auxinen, Gibberellinen, Abscisinsäure und Äthylen auch Cytokinine in das Wachstums- und Entwicklungsgeschehen der Traubenbeeren eingeschaltet sind

Multi-gap superconductivity in a BaFe1.84Co0.16As2 film from optical measurements at terahertz frequencies

We measured the THz reflectance properties of a high quality epitaxial thin film of the Fe-based superconductor BaFe$_{1.84}$Co$_{0.16}$As$_2$ with T$_c$=22.5 K. The film was grown by pulsed laser deposition on a DyScO$_3$ substrate with an epitaxial SrTiO$_3$ intermediate layer. The measured $R_S/R_N$ spectrum, i.e. the reflectivity ratio between the superconducting and normal state reflectance, provides clear evidence of a superconducting gap $\Delta_A$ close to 15 cm$^{-1}$. A detailed data analysis shows that a two-band, two-gap model is absolutely necessary to obtain a good description of the measured $R_S/R_N$ spectrum. The low-energy $\Delta_A$ gap results to be well determined ($\Delta_A$=15.5$\pm$0.5 cm$^{-1}$), while the value of the high-energy gap $\Delta_B$ is more uncertain ($\Delta_B$=55$\pm$7 cm$^{-1}$). Our results provide evidence of a nodeless isotropic double-gap scenario, with the presence of two optical gaps corresponding to 2$\Delta/kT_c$ values close to 2 and 7.Comment: Published Versio

Pressure dependence of the charge-density-wave gap in rare-earth tri-tellurides

We investigate the pressure dependence of the optical properties of CeTe$_3$, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of $R$Te$_3$.Comment: 5 pages, 4 figure

Interplay of the electronic and lattice degrees of freedom in A_{1-x}Fe_{2-y}Se_{2} superconductors under pressure

The local structure and electronic properties of Rb$_{1-x}$Fe$_{2-y}$Se$_2$ are investigated by means of site selective polarized x-ray absorption spectroscopy at the iron and selenium K-edges as a function of pressure. A combination of dispersive geometry and novel nanodiamond anvil pressure-cell has permitted to reveal a step-like decrease in the Fe-Se bond distance at $p\simeq11$ GPa. The position of the Fe K-edge pre-peak, which is directly related to the position of the chemical potential, remains nearly constant until $\sim6$ GPa, followed by an increase until $p\simeq 11$ GPa. Here, as in the local structure, a step-like decrease of the chemical potential is seen. Thus, the present results provide compelling evidence that the origin of the reemerging superconductivity in $A_{1-x}$Fe$_{2-y}$Se$_2$ in vicinity of a quantum critical transition is caused mainly by the changes in the electronic structure

Colloidal Radioalbumin Aggregates for Organ Scanning

Colloidal aggregates (10 to 20 m mu ) of human serum albumin /sup 131/I may be used safely by intravenous injection to perform photoscans of the heart, liver, spleen, stomach, and salivary glands in man. Large particle size suspensions (10 to 50 mu ) of the same material were investigated experimentally in animals for scanning the lungs after intravenous injection and the brain following injection into an internal carotid artery. The advantages of this test material are the relatively low radiation exposure to the target organs and the number of organs that may be examined. Radiation exposure is low because of the rapid turnover in the target organs and removal from the body, mainly by urinary excretion, within 72 hr. The mechanism of liverspleen localization with this organic colloid is the same as for inorganic colloidal /sup 198/Au, namely, rapid removal from the blood by the phagocytic cells of the liver and spleen. However, in contrast to the inorganic colloid, which remains in the phagocytic cells permanently, albumin is digested by proteolytic enzymes and the /sup 131/I label is set free to re-enter the general circulation. With the thyroid blocked, the / sup 131/ is excreted mainly in the urine as free iodide together with other labeled albumin degradation products, such as tyrosine and peptides. The calculated radiation dose to the liver is at least 100 times less from colloidal albumin Jail than from an equal dose of /sup 198/Au. (auth

DELAYED BRAIN SCANNING WITH /sup 99m/Tc PERTECHNETATE FOR IMPROVED TUMOR DETECTABILITY.

This investigation describes the results of 99m Tc pertechnetate brain scans performed during the first hour following tracer injection and of rescanning selected patients one to twenty four hours later

East Asia and the global/transatlantic/Western crisis

This paper introduces the special collection on East Asia and the Global Crisis. After justifying why a focus on East Asia is appropriate, it draws out the main themes that run through the individual contributions. These are the extent to which the region is decoupling from the global economy (or the West), the increasing legitimacy of statist alternatives to neoliberal development strategies, and the impact of crises on the definition of ―region‖ and the functioning of regional institutions and governance mechanisms

Ecosystem carbon 7 dioxide fluxes after disturbance in forests of North America

Disturbances are important for renewal of North American forests. Here we summarize more than 180 site years of eddy covariance measurements of carbon dioxide flux made at forest chronosequences in North America. The disturbances included stand-replacing fire (Alaska, Arizona, Manitoba, and Saskatchewan) and harvest (British Columbia, Florida, New Brunswick, Oregon, Quebec, Saskatchewan, and Wisconsin) events, insect infestations (gypsy moth, forest tent caterpillar, and mountain pine beetle), Hurricane Wilma, and silvicultural thinning (Arizona, California, and New Brunswick). Net ecosystem production (NEP) showed a carbon loss from all ecosystems following a stand-replacing disturbance, becoming a carbon sink by 20 years for all ecosystems and by 10 years for most. Maximum carbon losses following disturbance (g C m−2y−1) ranged from 1270 in Florida to 200 in boreal ecosystems. Similarly, for forests less than 100 years old, maximum uptake (g C m−2y−1) was 1180 in Florida mangroves and 210 in boreal ecosystems. More temperate forests had intermediate fluxes. Boreal ecosystems were relatively time invariant after 20 years, whereas western ecosystems tended to increase in carbon gain over time. This was driven mostly by gross photosynthetic production (GPP) because total ecosystem respiration (ER) and heterotrophic respiration were relatively invariant with age. GPP/ER was as low as 0.2 immediately following stand-replacing disturbance reaching a constant value of 1.2 after 20 years. NEP following insect defoliations and silvicultural thinning showed lesser changes than stand-replacing events, with decreases in the year of disturbance followed by rapid recovery. NEP decreased in a mangrove ecosystem following Hurricane Wilma because of a decrease in GPP and an increase in ER