Ba+2 ion trapping using organic submonolayer for ultra-low background neutrinoless double beta detector.

If neutrinos are their own antiparticles the otherwise-forbidden nuclear reaction known as neutrinoless double beta decay can occur. The very long lifetime expected for these exceptional events makes its detection a daunting task. In order to conduct an almost background-free experiment, the NEXT collaboration is investigating novel synthetic molecular sensors that may capture the Ba dication produced in the decay of certain Xe isotopes in a high-pressure gas experiment. The use of such molecular detectors immobilized on surfaces must be explored in the ultra-dry environment of a xenon gas chamber. Here, using a combination of highly sensitive surface science techniques in ultra-high vacuum, we demonstrate the possibility of employing the so-called Fluorescent Bicolor Indicator as the molecular component of the sensor. We unravel the ion capture process for these molecular indicators immobilized on a surface and explain the origin of the emission fluorescence shift associated to the ion trapping.

Adenopatía intramamaria metastásica como única manifestación de carcinoma mamario / Metastatic intramammary lymph node as the only manifestation of breast carcinoma

En el 5% de los estudios mamográficos de cribado se detectan adenopatías intramamarias. La ausencia de centro graso, la pérdida del hilio ganglionar, un tamaño superior al centímetro o un crecimiento con respecto a controles previos son motivos suficientes para realizar un estudio histológico de la adenopatía, con el objetivo de descartar enfermedad tumoral. A pesar del avance en los estudios radiológicos de cribado y el empleo generalizado de la técnica de biopsia selectiva del ganglio centinela en el tratamiento quirúrgico del carcinoma mamario precoz, el hallazgo de adenopatías intramamarias afectadas por tumor, en el carcinoma de mama infiltrante es generalmente un hallazgo casual durante la cirugía o en el subsiguiente exámen an atomopatológico. En la actualidad existe controversia en cuanto al manejo quirúrgico de la axila ante el hallazgo de una adenopatía intramamaria metastásica. Independientemente, tanto del manejo quirúrgico de la axila, como de la presencia o no de afectación tumoral ganglionar axilar, la afectación metastásica de una adenopatía intramamaria cambia no sólo el pronóstico de la paciente sino también la actitud en cuanto a terapia adyuvante (AU)

Abstract Intramammary lymph nodes are detected in 5% of screening mammographies. Suffi-cient grounds for histological examination to exclude malignancy are the absence of the hilarfatty radiolucent notch, a reduction in the volume of the central echogenic hilum, size greater than 1 cm or an increase in size compared with previous screens. Despite advances in radiological screening and the widespread use of sentinel lymph node biopsy in the surgical treatment of early breast carcinoma, breast cancer metastasis to intramammary lymph nodes is usually an incidental finding during surgery or in subsequent histological examination. The surgical treatment of the axilla in cases of metastatic intramammary lymph nodes is currently controversial. Independently of the surgical management of the axilla and the presence or absence of metastatic axillary lymph node, a finding of a metastatic intramammary lymph node changes not only the patient’s prognosis but also the approach to the use of adjuvant therapy (AU)

Photophysical properties of lumichromes in water.

The photophysics of lumichrome, 1-methyllumichrome, and lumiflavin in water solutions have been investigated. Fluorescence lifetimes of 2.7 and 2.2 ns were observed for lumichrome and 1-methyllumichrome, respectively, the corresponding triplet state lifetimes of 17 and 18 micros have been obtained from the transient absorption spectra. Evidence for long lived species with absorption maxima near 450 nm and lifetimes of ca. 400 micros has been found in the transient absorption spectra of both lumichromes. Quantum yields for the sensitised production of singlet oxygen, phi(Delta), are 0.36 and 0.41 for lumichrome and 1-methyllumichrome, respectively, in D(2)O.

On the Z-E photoisomerization of chiral 2-pentenoate esters: stationary irradiations, laser-flash photolysis studies, and theoretical calculations.

Chiral pentenoates 1-3 in both Z and E isomeric forms underwent stationary irradiations in several solvents and in the presence of different photosensitizers. The photostationary-state ratio has been determined for each Z/E couple showing a predominance of the thermodynamically more stable isomer for 1 and 3. Moreover, transient species were generated by pulsed laser excitation and detected by their characteristic ultraviolet absorptions, being the first time that enoate-originated triplets are detected. Stern-Volmer quenching studies afforded a quantitative measure for the efficiency of the photosensitization processes induced by benzophenone or acetophenone and allowed the determination of the corresponding quenching rate constants. Density functional calculations permitted the determination of the geometries and the energies of the diastereomeric excited states. Two diastereomeric orthogonal and two diastereomeric planar structures result as a consequence of the presence of a chiral substituent. The orthogonal triplets are the energy minima in all cases, whereas the planar triplets are the transition states linking these orthogonal structures, the corresponding energy barriers being 8-10 kcal mol(-1) for enoates 1-3. The computed S(0) to T(1) excitation energies show a trend which is consistent with the quenching rate constants. On the other hand, the triplet lifetimes determined for 1 and 2 are unusually long (1-20 micros) if compared with the data already described for several enones, in the range of nanoseconds. This fact has been rationalized from calculations of spin-orbit coupling at several points of the T(1) potential energy surface. This coupling is maximum for structures with a torsional angle close to 45 degrees, which are 4-5 kcal mol(-1) above the minima of T(1). Calculations done on the hypothetical aldehyde 4 and methyl vinyl ketone show much lower energy barriers, thus accounting for the shorter lifetimes reported for enone triplets.

Opening the Schiff base moiety of bacteriorhodopsin by mutation of the four extracellular Glu side chains.

The quadruple bacteriorhodopsin (BR) mutant E9Q+E74Q+E194Q+E204Q shows a lambda(max) of about 500 nm in water at neutral pH and a great influence of pH and salts on the visible absorption spectrum. Accessibility to the Schiff base is strongly increased, as detected by the rapid bleaching effect of hydroxylamine in the dark as well as in light. Both the proton release kinetics and the photocycle are altered, as indicated by a delayed proton release after proton uptake and changed M kinetics. Moreover, affinity of the color-controlling cation(s) is found to be decreased. We suggest that the four Glu side chains are essential elements of the extracellular structure of BR.