Assessment of crystalline materials for solid state lighting applications: Beyond the rare earth elements

In everyday life, we are continually exposed to different lighting systems, from the home interior to car lights and from public lighting to displays. The basic emission principles on which they are based range from the old incandescent lamps to the well-established compact fluorescent lamps (CFL) and to the more modern Light Emitting Diode (LEDs) that are dominating the actual market and also promise greater development in the coming years. In the LED technology, the key point is the electroluminescence material, but the fundamental role of proper phosphors is sometimes underestimated even when it is essential for an ideal color rendering. In this review, we analyze the main solid-state techniques for lighting applications, paying attention to the fundamental properties of phosphors to be successfully applied. Currently, the most widely used materials are based on rare-earth elements (REEs) whereas Ce:YAG represents the benchmark for white LEDs. However, there are several drawbacks to the REEs’ supply chain and several concerns from an environmental point of view. We analyze these critical issues and review alternative materials that can overcome their use. New compounds with reduced or totally REE free, quantum dots, metal–organic framework, and organic phosphors will be examined with reference to the current state-of-the-art

A microscopic description of the aging dynamics: fluctuation-dissipation relations, effective temperature and heterogeneities

We consider the dynamics of a diluted mean-field spin glass model in the aging regime. The model presents a particularly rich heterogeneous behavior. In order to catch this behavior, we perform a **spin-by-spin analysis** for a **given disorder realization**. The results compare well with the outcome of a static calculation which uses the ``survey propagation'' algorithm of Mezard, Parisi, and Zecchina [Sciencexpress 10.1126/science.1073287 (2002)]. We thus confirm the connection between statics and dynamics at the level of single degrees of freedom. Moreover, working with single-site quantities, we can introduce a new response-vs-correlation plot, which clearly shows how heterogeneous degrees of freedom undergo coherent structural rearrangements. Finally we discuss the general scenario which emerges from our work and (possibly) applies to more realistic glassy models. Interestingly enough, some features of this scenario can be understood recurring to thermometric considerations.Comment: 4 pages, 5 figures (7 eps files

Compton processes in the bright AGN MCG+8-11-11

We present preliminary results on the hard X-ray emission properties of the Seyfert 1.5 galaxy MCG+8-11-11 as observed by INTEGRAL and SWIFT. All the INTEGRAL IBIS/ISGRI data available up to October 2009 have been analyzed together with two SWIFT/XRT snapshot observations performed in August and October 2009, quasi-simultaneously to INTEGRAL pointed observations of MCG+8-11-11. No correlation is observed between the hard X-ray flux and the spectral slope, while the position of the high-energy cut-off is found to have varied during the INTEGRAL observations. This points to a change in the temperature of the Comptonising medium from a minimum value of kT = 30-50 keV to values larger than 100-150 keV. There is no significant detection of Compton reflection, with a 3 sigma upper limit of R < 0.2, and no line has been detected at 112 keV, as previously claimed from HEAT observations (112 keV flux F < 2.4e-4 ph/cm^2/s). The variability behaviour of MCG+8-11-11 is found to be similar to that shown by IC 4329A, with different temperatures of the electron plasma for similar flux levels of the source, while other bright Seyfert galaxies present different variability patterns at hard X-rays, with spectral changes correlated to flux variations (e.g. NGC 4151).Comment: 6 pages, 4 figures. Accepted for publication on PoS (contribution PoS(INTEGRAL 2010)077), proceedings of the 8th INTEGRAL Workshop "The Restless Gamma-ray Universe" (September 2010, Dublin, Ireland

Modifications of the hydrogen bond network of liquid water in a cylindrical SiO_2 pore

We present results of molecular dynamics simulations of water confined in a silica pore. A cylindrical cavity is created inside a vitreous silica cell with geometry and size similar to the pores of real Vycor glass. The simulations are performed at different hydration levels. At all hydration levels water adsorbs strongly on the Vycor surface; a double layer structure is evident at higher hydrations. At almost full hydration the modifications of the confinement-induced site-site pair distribution functions are in qualitative agreement with neutron diffraction experiment. A decrease in the number of hydrogen bonds between water molecules is observed along the pore radius, due to the tendency of the molecules close to the substrate to form hydrogen-bonds with the hydrophilic pore surface. As a consequence we observe a substrate induced distortion of the H-bond tetrahedral network of water molecules in the regions close to the surface.Comment: Talk presented at "Physics of Liquids: Foundations, Highlights, Challenge", Murau Sept. 1998. To appear in J. Mol. Li

Trapping dust particles in the outer regions of protoplanetary disks

Aims. We attempt to explain grain growth to mm sized particles and their retention in the outer regions of protoplanetary disks, as observed at sub-mm and mm wavelengths, by investigating whether strong inhomogeneities in the gas density profiles can decelerate excessive radial drift and help the dust particles to grow. Methods. We use coagulation/fragmentation and disk-structure models, to simulate the evolution of dust in a bumpy surface density profile, which we mimic with a sinusoidal disturbance. For different values of the amplitude and length scale of the bumps, we investigate the ability of this model to produce and retain large particles on million-year timescales. In addition, we compare the pressure inhomogeneities considered in this work with the pressure profiles that come from magnetorotational instability. Using the Common Astronomy Software Applications ALMA simulator, we study whether there are observational signatures of these pressure inhomogeneities that can be seen with ALMA. Results. We present the conditions required to trap dust particles and the corresponding calculations predicting the spectral slope in the mm-wavelength range, to compare with current observations. Finally, we present simulated images using different antenna configurations of ALMA at different frequencies, to show that the ring structures will be detectable at the distances of either the Taurus Auriga or Ophiucus star-forming regions

Comparative US-MRI evaluation of the Insall–Salvati index

Purpose: To investigate whether the universally accepted range of normal patellar height ratio derived from MRI for the Insall–Salvati (IS) method could be similarly applied to ultrasound (US). Materials and methods: This study included 52 patients (age range 11–75&nbsp;years) who underwent a bi-modality (US and MRI) examination, with a total of 60 knees evaluated. IS index (ratio of the patella tendon length to length of the patella) was acquired with both methods. Two operators, with different experiences of musculoskeletal imaging and blinded to the results of other investigators, separately performed the MRI and US measurements. Results: For the two operators, MRI reported a mean value of patellar height ratio of 1.10&nbsp;±&nbsp;0.16 (mean&nbsp;±&nbsp;standard deviation SD), while US a mean value of 1.17&nbsp;±&nbsp;0.16 (mean&nbsp;±&nbsp;SD). For comparable results, the small addition of 0.16 is needed for the measurements on US compared with MRI. Inter-observer agreements using intra-class correlation coefficient (ICC) was, respectively, 0.97 for MRI and 0.98 for US. The difference of mean values in patellar height ratios between MRI and US was not statistically significant (p&nbsp;=&nbsp;0.15). The ICC between the two modalities was 0.94. Conclusion: According to our experience, IS index can be appropriately evaluated on US images, reducing the need of other imaging techniques

Metronomic Chemotherapy with Vinorelbine Produces Clinical Benefit and Low Toxicity in Frail Elderly Patients Affected by Advanced Non-Small Cell Lung Cancer

Lung cancer is the leading cause of death worldwide. The treatment choice for advanced stage of lung cancer may depend on histotype, performance status (PS), age, and comorbidities. In the present study, we focused on the effect of metronomic vinorelbine treatment in elderly patients with advanced unresectable non-small cell lung cancer (NSCLC). Methods. From January 2016 to December 2016, 44 patients affected by non-small cell lung cancer referred to our oncology day hospital were progressively analyzed. The patients were treated with oral vinorelbine 30 mg x 3/wk or 40 mg x 3/wk meaning one day on and one day off. The patients were older than 60, stage IIIB or IV, ECOG PS ≥ 1, and have at least one important comorbidity (renal, hepatic, or cardiovascular disease). The schedule was based on ECOG-PS and comorbidities. The primary endpoint was progression-free survival (PFS). PFS was used to compare patients based on different scheduled dosage (30 or 40 mg x3/weekly) and age (more or less than 75 years old) as exploratory analysis. We also evaluated as secondary endpoint toxicity according to Common Toxicity Criteria Version 2.0. Results. Vinorelbine showed a good safety profile at different doses taken orally and was effective in controlling cancer progression. The median overall survival (OS) was 12 months. The disease control rate (DCR) achieved 63%. The median PFS was 9 months. A significant difference in PFS was detected comparing patients aged below with those over 75, and the HR value was 0.72 (p<0.05). Not significant was the difference between groups with different schedules. Conclusions. This study confirmed the safety profile of metronomic vinorelbine and its applicability for patients unfit for standard chemotherapies and adds the possibility of considering this type of schedule not only for very elderly patients