An experimental procedure using monoenergetic Synchrotron Radiation x‐ray Fluorescence (SR‐XRF) method was studied, justified and applied to determine trace elements concentrations of normal and neoplastic human breast tissues in the same individual. Scattered radiation from each sample was used as an internal standard in x‐ray emission spectroscopy in order to construct calibration curves used to determine Ca, Fe, Cu and Zn concentrations in 52 breast tissue specimens (26 neoplastic and 26 adjacent normal tissues).This work showed that this experimental alternative is approximately matrix independent and also allows a reduction in instrumental variables. Our results showed, as expected, that Ca, Fe, Cu and Zn concentrations levels were significantly higher in neoplastic than in healthy breast tissues (all p < 0.001). It was also observed that Fe and Cu levels are correlated in malignant breast tissues as well as Ca and Zn levels, indicating that these elements' concentrations are related, in agreement with the hypothesis that there is a connection between Fe and Cu with both increased cellular activity and blood supply in the formation of neoplasies in breast tissue, and between Ca and Zn as regulators of neoplasies growth, since these metals are present in active matrix metalloproteinases (MMPs). Copyright © 2008 John Wiley & Sons, Ltd.

The citrus (Citrus sinensis) cyclophilin CsCyp is a target of the Xanthomonas citri transcription activator-like effector PthA, required to elicit cankers on citrus. CsCyp binds the citrus thioredoxin CsTdx and the carboxyl-terminal domain of RNA polymerase II and is a divergent cyclophilin that carries the additional loop KSGKPLH, invariable cysteine (Cys) residues Cys-40 and Cys-168, and the conserved glutamate (Glu) Glu-83. Despite the suggested roles in ATP and metal binding, the functions of these unique structural elements remain unknown. Here, we show that the conserved Cys residues form a disulfide bond that inactivates the enzyme, whereas Glu-83, which belongs to the catalytic loop and is also critical for enzyme activity, is anchored to the divergent loop to maintain the active site open. In addition, we demonstrate that Cys-40 and Cys-168 are required for the interaction with CsTdx and that CsCyp binds the citrus carboxyl-terminal domain of RNA polymerase II YSPSAP repeat. Our data support a model where formation of the Cys-40-Cys-168 disulfide bond induces a conformational change that disrupts the interaction of the divergent and catalytic loops, via Glu-83, causing the active site to close. This suggests a new type of allosteric regulation in divergent cyclophilins, involving disulfide bond formation and a loop-displacement mechanism.

We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 0:003 < x < 0 : 7. From these asymmetries and the previously published inclusive spin asymmetries we determine, for the rst time, the x-dependent spin distributions for up and down valence quarks and for non-strange sea quarks. We nd that the rst moments of the valence quark Recent results from the polarised inclusive deep inelastic scattering of leptons by protons and deuterons [1,2,3,4,5] show that the quark spins contribute only about 20% to the nucleon spin with a relatively large negative contribution of about 10% from the strange quarks. These conclusions are based on the analysis of the rst moments of the spin-dependent structure functions g 1 (x) of the proton and deuteron in the framework of the quark parton model (QPM). More detailed information on the spin structure of the nucleon can be obtained from polarised semi-inclusive deep inelastic scattering, where in addition to the scattered lepton also hadrons are detected. An early theoretical pre-

Electron spin resonance ͑ESR͒ experiments at different fields or frequencies ͑4.1Յ Յ 34.4 GHz͒ in the Kondo lattice ͑T K Ӎ 25 K͒ YbRh 2 Si 2 single-crystal compounds confirmed the observation of a single anisotropic Dysonian resonance with g Ќc Х 3.55 and no hyperfine components for 4.2Շ T Շ 20 K. However, our studies differently reveal that ͑i͒ the ESR spectra for H Ќc show strong-field-dependent spin-lattice relaxation, ͑ii͒ a weak-field and temperature-dependent effective g value, ͑iii͒ a dramatic suppression of the ESR intensity beyond 15% of Lu doping, and ͑iv͒ a strong sample and Lu-doping ͑Յ15%͒ dependence of the ESR data. These results suggest a different scenario where the ESR signal may be associated to a coupled Yb 3+ -conduction electron resonant collective mode with a strong bottleneck and dynamiclike behavior.

Long-range order evolution of self-assembled phosphonic acid multilayers as a function of temperature is studied here for two molecules with different alkyl chain length. By using synchrotron conventional diffraction, distinct order configurations are retrieved on phosphonic acid multilayers and their thermodynamic behavior monitored by energy-dispersive diffraction. This later technique allows us to observe the system behavior near order-disorder temperatures, as well as to determine the most stable configurations in the range from room temperature up to 120 °C. Planar order is also addressed by wide-angle X-ray scattering (WAXS) transmission experiments. Order parameter phase diagrams are built based on the experimental results, showing the dominant configuration at each temperature. The multilayer molecular long-range order retrieved from the experiments is corroborated by first principles calculations based on the Density Functional Theory. The bulk configurations depicted in this work are produced by molecule-molecule interactions and allow for future comparisons with the behavior of ordered molecules in few-monolayers configurations, commonly used in organic devices, where the presence of surfaces and interfaces strongly affects the molecule packing.

The x-ray fluorescence beamline of the Laboratorio Nacional de Luz Síncrotron (LNLS) is described. The main optical component of the beamline is a silicon (111) channel-cut monochromator, which can tune energies between 3 and 14 keV. A general description of two experimental stations is given. Beam characterization was done by measuring experimental parameters such as vertical profile and monochromatic flux. These results show that the photon flux at 8 keV in an area of 20 mm 2 is 4.2 × 10 9 photons s −1 . The possibility of achieving fine tuning of energies (high resolution) was confirmed. This paper presents some original results derived from the commissioning of the beamline, such as a comparison of detection limits in different experimental conditions, and a novel mechanical system to align capillaries together with a semi-automatic adjustment procedure. So far, there have been several proposals to perform a variety of experiments at this beamline, covering different fields, such as physics, chemistry, geology and biology.

We present a new measurement of the spin-dependent structure function g d 1 of the deuteron in deep inelastic scattering of 190 GeV polarised muons on polarised deuterons, in the kinematic range 0:003 < x < 0 : 7 and 1 GeV 2 < Q 2 < 60 GeV 2 . This structure function is found to be negative at small

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