No abstract

Whereas efficient and sensitive nanoheaters and nanothermometers are demanding tools in modern bio-and nanomedicine, joining both features in a single nanoparticle still remains a real challenge, despite the recent progress achieved, most of it within the last year. Here we demonstrate a successful realization of this challenge. The heating is magnetically induced, the temperature readout is optical, and the ratiometric thermometric probes are dual-emissive Eu 3þ /Tb 3þ lanthanide complexes. The low thermometer heat capacitance (0.021 3 K À1 ) and heater/thermometer resistance (1 K 3 W À1 ), the high temperature sensitivity (5.8% 3 K À1 at 296 K) and uncertainty (0.5 K), the physiological working temperature range (295À315 K), the readout reproducibility (>99.5%), and the fast time response (0.250 s) make the heater/thermometer nanoplatform proposed here unique. Cells were incubated with the nanoparticles, and fluorescence microscopy permits the mapping of the intracellular local temperature using the pixel-by-pixel ratio of the Eu 3þ /Tb 3þ intensities. Time-resolved thermometry under an ac magnetic field evidences the failure of using macroscopic thermal parameters to describe heat diffusion at the nanoscale.

A precise measurement of p̄p elastic scattering in the Coulomb-strong interaction interference region was performed at the CERN Sp̄pS Collider at a centre-of-mass energy of 541 GeV. The ratio of the real to the imaginary part of the forward elastic scattering amplitude was found to be ρ = 0.135 ± 0.015. The slope of the exponential fall off of the strong interaction part was also measured to be b = 15.5 ± 0.1 GeV−2

The core antenna complexes of photosystem II, CP43 and CP47, were purified from two higher plants by anion-exchange chromatography, using a combination of the chaotropic agent UCIO4 and the nonionic detergent /3-dodecyl maltoside. The Qy transition was resolved at 48 K into two main bands near 682.3 and 671.5 nm for CP43, while the CP47 spectrum showed a more complex structure with main bands at 688, 681.2, 676, 670, 667, and 661 nm. Emission bands (77 K) were detected at 683 and 695 nm for CP43 and CP47, respectively. Fluorescence excitation spectra showed high efficiency of energy transfer between the different transitions of the chlorophylls and a somewhat lower efficiency from /3-carotene. The circular dichroism spectrum of CP47 indicated the presence of excitonic interactions between some chlorophylls. In contrast, CP43 showed a single negative circular dichroism band at 670 nm. The pigment content of the complexes was determined by both spectroscopic measurements and HPLC. Contents of 18 chlorophylls a and 5 /3-carotenes per CP43 polypeptide and 19 chlorophylls a and 3 /3-carotenes per CP47 polypeptide were found, using the methods of Lowry or Bradford for protein quantitation. When the protein concentration was determined from the amino acid analysis, 20 chlorophylls a and 5 /3-carotenes per CP43 and 21-22 chlorophylls a and 4 /3-carotenes per CP47 were obtained. Thus, a content of 46-48 chlorophylls a was obtained for the core complex, assuming 4-6 chlorophylls per reaction center, in agreement with the composition obtained experimentally using a highly purified oxygen-evolving core complex. This suggested that no pigments were lost during the purification procedure. Moreover, the amino acid analysis of the purified complexes revealed a high homology with the amino acid composition derived from the gene sequences reported for other higher plants.Photosystem (PS1) II is a membrane protein complex present in all oxygenic photosynthetic organisms. The smaller particle of PSII isolated so far, which is able to retain the primary processes of photosynthesis, i.e., charge separation, quinone reduction, and oxygen evolution, is a particle called the oxygenevolving core complex (OECC) (Ghanotakis & Yocum, 1986). This particle consists of eight main polypeptides, i.e., Di and D2, the a-and /3-subunits of cytochrome (Cyt) 6559, the psbl gene product of the reaction center (RC), the core antennae CP43 and CP47, and the 33-kDa extrinsic protein. Many * This work was supported by the Direccibn General de Investigacibn Cientifica y Tecnica (DGICYT, Grant PB92-0125). M.A. and G.M. are grateful to the Direccibn de Polltica Cientifica Gobierno Vasco and the CONAI-Diputacibn General Aragbn, respectively, for financial support.