Experimental Determination of Power Losses and Heat Generation in Solar Cells for Photovoltaic-Thermal Applications

Solar cell thermal recovery has recently attracted more and more attention as a viable solution to increase photovoltaic efficiency. However, the convenience of the implementation of such a strategy is bound to the precise evaluation of the recoverable thermal power and to a proper definition of the losses occurring within the solar device. In this work, we establish a framework in which all solar cell losses are defined and described. The aim is to determine the components of the thermal fraction. We therefore describe an experimental method to precisely compute these components from the measurement of the external quantum efficiency, the current–voltage characteristics, and the reflectivity of the solar cell. Applying this method to three different types of devices (bulk, thin film, and multi-junction), we could exploit the relationships among losses for the main three generations of PV cells available nowadays. In addition, since the model is explicitly wavelength dependent, we could show how thermal losses in all cells occur over the whole solar spectrum, and not only in the infrared region. This demonstrates that profitable thermal harvesting technologies should enable heat recovery over the whole solar spectral range.     

HVPTF—The high voltage laboratory for the ITER Neutral Beam test facility

In the MITICA research program for the construction of the ITER Neutral Beam Injector prototype, a Laboratory for the investigation on high voltage holding in vacuum has been set up. This Laboratory - HVPTF: High Voltage Padova Test Facility - is presently capable of experiments up to 300 kV dc, and planned for the upgrade to 800 kV. The specific mission for this ancillary lab is the support to the electrostatic design and construction of the MITICA accelerator and the development and testing of HV components to be installed inside the MITICA accelerator during its operation.The paper describes the structure of the lab, characterized by a high degree of automation and reports the results of the commissioning at 300 kV and the first results of voltage holding between test electrodes.     

Nanovoid Formation and Dynamics in He+-Implanted Nanocrystalline Silicon

Helium implantation in single crystal silicon is known to lead, after a proper thermal treatment, to the formation of voids with diameters ranging between 10 nm and 30 nm. Formation of voids is governed by the coalescence of vacancies created by implantation, initially trapping helium atoms. At high temperatures ( \({\ge}700^{\circ }\hbox {C}\) ), helium leaves the nanobubbles and outdiffuses, while the now empty voids grow in size and eventually change their shape to form tetrakaidecahedra (Wulff construction). In this communication, we report how He⁺ implantation in heavily boron-doped nanocrystalline silicon shows a completely different dynamics. Annealing at \(500^{\circ }\hbox {C}\) leads to the formation of large voids, located around grain boundaries, along with a large number of nanovoids with an average diameter of 2–4 nm and an estimated density of \(3\times 10^{17}\,\hbox {cm}^{-3}\) distributed throughout the grains. Annealing at higher temperature (up to \(1000^{\circ }\hbox {C}\) ) also induces a decrease of the void size with a change in their density, finally accounting to \(2\times 10^{18}\,\hbox {cm}^{-3}\) . The high temperature annealing also causes vacancy evaporation down to a depth of 80–100 nm from the outer surface. The possibility of obtaining a stable, uniform distribution of nanometer-sized voids is of major relevance as a novel tool for phonon and electron engineering in thermoelectric materials.     

Special considerations concerning regulatory requirements and drug development for peptides and biotech products in the EU

The marketing authorization for a new medicinal product is based on the scientific assessment of its quality, safety and efficacy. The marketing authorization application (MAA) which covers all the relevant documentation can be filed in the EU via different application procedures. For peptides and biological products special issues have to be taken into consideration during drug development. Due to special production procedures and the complexity of the active substance itself, peptides and biotech products are subject to specific regulatory requirements. This leads to the necessity to discuss the development program of a new peptide or biotech product with the health authorities on a case by case basis. This article will focus on the special regulatory requirements for peptides and biotech products including the registration procedures as well as technical, preclinical and clinical issues.     

Synthesis, enantiomeric resolution, and structure-activity relationship study of a series of 10,11-dihydro-5H-dibenzo[a,d]cycloheptene MT2 receptor antagonists

Racemic N-(8-methoxy-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-10-ylmethyl)acetamide (compound 5) was previously identified as a novel selective MT(2) antagonist fulfilling the requirements of pharmacophore and 3D QSAR models. In this study the enantiomers of 5 were separated by medium-pressure liquid chromatography and behaved as the racemate. Compound 5 was modified at the acylaminomethyl side chain and at position C8. The resulting analogues generally behaved as melatonin receptor antagonists (GTPgammaS test) with a modest degree of selectivity (up to 10-fold) for the MT(2) receptor. Changes at the amide side chain led to a decrease in binding affinity, whereas 8-acetyl and 8-methyl derivatives 12 and 11, respectively, were as potent as the 8-methoxy parent compound 5. Docking experiments with an MT(2) receptor model suggested binding modes consistent with the observed SARs and with the lack of selectivity of the enantiomers of 5.     

Efficient Parallel Transport of Deformations in Time Series of Images: From Schild’s to Pole Ladder

Group-wise analysis of time series of images requires to compare longitudinal evolutions of images observed on different subjects. In medical imaging, longitudinal anatomical changes can be modeled thanks to non-rigid registration of follow-up images. The comparison of longitudinal trajectories requires the transport (or “normalization”) of longitudinal deformations in a common reference frame. We previously proposed an effective computational scheme based on the Schild’s ladder for the parallel transport of diffeomorphic deformations parameterized by tangent velocity fields, based on the construction of a geodesic parallelogram on a manifold. Schild’s ladder may be however inefficient for transporting longitudinal deformations from image time series of multiple time points, in which the computation of the geodesic diagonals is required several times. We propose here a new algorithm, the pole ladder, in which one diagonal of the parallelogram is the baseline-to-reference frame geodesic. This drastically reduces the number of geodesics to compute. Moreover, differently from the Schild’s ladder, the pole ladder is symmetric with respect to the baseline-to-reference frame geodesic. From the theoretical point of view, we show that the pole ladder is rigorously equivalent to the Schild’s ladder when transporting along geodesics. From the practical point of view, we establish the computational advantages and demonstrate the effectiveness of this very simple method by comparing with standard methods of transport on simulated images with progressing brain atrophy. Finally, we illustrate its application to a clinical problem: the measurement of the longitudinal progression in Alzheimer’s disease. Results suggest that an important gain in sensitivity could be expected in group-wise comparisons.