Hierarchies and Dominance Behaviors in European Pond Turtle (Emys orbicularis galloitalica) Hatchlings in a Controlled Environment.

Few species of reptiles are known to establish stable social structures and among these, chelonians provided scarce and conflicting results. Moreover, studies on turtles are usually performed on adult individuals. In this study, we checked whether and when hatchlings of the European Pond Turtle (Emys orbicularis galloitalica) established stable hierarchical structures in their first year of life, whether hierarchies were stable in time and how steady they were. We also verified whether social ranks were associated to the individuals' size. We observed dyadic interactions daily within three small groups of turtles reared in a controlled environment for seven months. After two months, the hatchlings started to interact and progressively established stable hierarchical structures. However, the effectiveness of the three types of observed aggressive behaviors in reversing social ranks was low and the resulting hierarchies were flat. We did not find a significant effect of the turtles' size on their interactions' outcome and hierarchy structure. Our results provide clear evidence of the development and the characteristics of social behaviors in young reptiles in captivity. This study could be a starting point for investigating social structures in wild populations.

Radiation hardness of Ce-doped sol-gel silica fibers for high energy physics applications.

The results of irradiation tests on Ce-doped sol-gel silica using x- and γ-rays up to 10 kGy are reported in order to investigate the radiation hardness of this material for high-energy physics applications. Sol-gel silica fibers with Ce concentrations of 0.0125 and 0.05 mol. % are characterized by means of optical absorption and attenuation length measurements before and after irradiation. The two different techniques give comparable results, evidencing the formation of a main broad radiation-induced absorption band, peaking at about 2.2 eV, related to radiation-induced color centers. The results are compared with those obtained on bulk silica. This study reveals that an improvement of the radiation hardness of Ce-doped silica fibers can be achieved by reducing Ce content inside the fiber core, paving the way for further material development.

"Quantized" Doping of Individual Colloidal Nanocrystals Using Size-Focused Metal Quantum Clusters.

The insertion of intentional impurities, commonly referred to as doping, into colloidal semiconductor quantum dots (QDs) is a powerful paradigm for tailoring their electronic, optical, and magnetic behaviors beyond what is obtained with size-control and heterostructuring motifs. Advancements in colloidal chemistry have led to nearly atomic precision of the doping level in both lightly and heavily doped QDs. The doping strategies currently available, however, operate at the ensemble level, resulting in a Poisson distribution of impurities across the QD population. To date, the synthesis of monodisperse ensembles of QDs individually doped with an identical number of impurity atoms is still an open challenge, and its achievement would enable the realization of advanced QD devices, such as optically/electrically controlled magnetic memories and intragap state transistors and solar cells, that rely on the precise tuning of the impurity states (i.e., number of unpaired spins, energy and width of impurity levels) within the QD host. The only approach reported to date relies on QD seeding with organometallic precursors that are intrinsically unstable and strongly affected by chemical or environmental degradation, which prevents the concept from reaching its full potential and makes the method unsuitable for aqueous synthesis routes. Here, we overcome these issues by demonstrating a doping strategy that bridges two traditionally orthogonal nanostructured material systems, namely, QDs and metal quantum clusters composed of a "magic number" of atoms held together by stable metal-to-metal bonds. Specifically, we use clusters composed of four copper atoms (Cu4) capped with d-penicillamine to seed the growth of CdS QDs in water at room temperature. The elemental analysis, performed by electrospray ionization mass spectrometry, X-ray fluorescence, and inductively coupled plasma mass spectrometry, side by side with optical spectroscopy and transmission electron microscopy measurements, indicates that each Cu:CdS QD in the ensemble incorporates four Cu atoms originating from one Cu4 cluster, which acts as a "quantized" source of dopant impurities.

Real-time dosimetry with Yb-doped silica optical fibres.

Over the years, many efforts have been made to develop radiation detectors to handle the complex issues of small field dosimetry and achieve the increasing accuracy, precision and in vivo dose monitoring required by the new advanced treatment modalities. In this context, interest has surged in the development of sensors based on scintillating optical fibres. In this paper, the near-infrared radioluminescence and dosimetric properties of Yb-doped silica optical fibres, coupled with a laboratory prototype based on an avalanche photodiode, were studied by irradiating the fibres with photons and electron beams generated by a Varian Trilogy accelerator. The performance of the system in standard and small field sizes has also been investigated, comparing the output factor, percentage depth dose and off-axis ratio measurements of the prototypal detector with other commercial sensors, including the Exradin W1 scintillator. The results of this study demonstrate that the drawback due to the stem effect in Yb-doped silica optical fibres can be managed in a simple but effective way by optical filtering. The robustness of the system in complex dosimetric scenarios and the accuracy and precision achieved by Yb-doped fibres in relative dose assessments suggest an effective use of the system for real-time in vivo dosimetry applications.

Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices.

The development of integrated photonics and lab-on-a-chip platforms for environmental and biomedical diagnostics demands ultraviolet electroluminescent materials with high mechanical, chemical and environmental stability and almost complete compatibility with existing silicon technology. Here we report the realization of fully inorganic ultraviolet light-emitting diodes emitting at 390 nm with a maximum external quantum efficiency of ~0.3%, based on SnO(2) nanoparticles embedded in SiO(2) thin films obtained from a solution-processed method. The fabrication involves a single deposition step onto a silicon wafer followed by a thermal treatment in a controlled atmosphere. The fully inorganic architecture ensures superior mechanical robustness and optimal chemical stability in organic solvents and aqueous solutions. The versatility of the fabrication process broadens the possibility of optimizing this strategy and extending it to other nanostructured systems for designed applications, such as active components of wearable health monitors or biomedical devices.