Surface Encapsulation for Low-Loss Silicon Photonics

Encapsulation layers are explored for passivating the surfaces of silicon to reduce optical absorption in the 1500-nm wavelength band. Surface-sensitive test structures consisting of microdisk resonators are fabricated for this purpose. Based on previous work in silicon photovoltaics, coatings of SiNx and SiO2 are applied under varying deposition and annealing conditions. A short dry thermal oxidation followed by a long high-temperature N2 anneal is found to be most effective at long-term encapsulation and reduction of interface absorption. Minimization of the optical loss is attributed to simultaneous reduction in sub-bandgap silicon surface states and hydrogen in the capping material.Comment: 4 pages, 3 figure

Numerical and experimental efficiency estimation in household battery energy storage equipment

Battery energy storage systems (BESS) are spreading in several applications among transmission and distribution networks. Nevertheless, it is not straightforward to estimate their performances in real life working conditions. This work is aimed at identifying test power profiles for stationary residential storage applications capable of estimating BESS performance. The proposed approach is based on a clustering procedure devoted to group daily power profiles according to their battery efficiency. By performing a k-means clustering on a large dataset of load and generation profiles, four standard charge/discharge profiles have been identified to test BESS' performances. Different clustering approaches have been considered, each of them splitting the dataset according to different properties of the profiles. A well-performing clustering approach resulted, based on the adoption of reference parameters for the clustering process of the maximum power exchanged by the BESS and the variation of battery energy content. Firstly, the results have been proven through a numerical procedure based on a BESS electrical model and on the definition of a key performance index. Then, an experimental validation has been carried out on a precommercial sodium-nickel chloride BESS: this device is available in the IoT lab of Politecnico di Milano within the H2020 InteGRIDy project

Influence of particle density on flow behavior and deposit architecture of concentrated pyroclastic density currents over a break in slope: Insights from laboratory experiments

Geological granular flows are highly complex, gravity-driven phenomena whose different behaviors depend on the mechanical properties, density and granulometric distributions of the constituent materials. Years of research have produced significant advances in understanding transport and deposition processes in granular flows. However, the role and effects of clast densities and density contrast in a granular flow are still not fully understood. In this paper we show the effect that pumice has on dry granular flows; specifically on flow velocity and longitudinal segregation of the deposits. Our work confirms, by experimental results, field observations on pumice/lithic segregation and longer pumice runout. We report results of velocity decay and deposit architecture for a granular flow passing over a break in slope (from 38° to 4° inclination). The 30 experimental runs were carried out in a five-meter long laboratory flume equipped with a series of sensors that include laser gates and high-speed cameras (400 fps). We used two polydisperse mixtures of dacitic lithics and rhyolitic pumice in varying amounts, with Weibull and Gaussian particle size distributions. The pumice/lithic ratio changes the flow response passing over a break in slope. This effect is particularly evident starting from 10% of pumice volume into the flow mixture, independently of its granulometric distribution. Runout relates to mass following a power law, with an exponent close 0.2. The experiments confirm that pumice segregation affects polydispersed mixtures, similarly to what has been observed in real field deposits, where density decoupling produces lithic-enriched proximal areas and pumice-enriched distal areas. The results obtained prove that the presence of low-density materials in a dense granular flow has a strong influence on its behavior

Outcomes of the addition of oral administration of curcumin-phospholipid to hyaluronic acid-based tear substitute for the treatment of dry eye disease

The aim of this study is to report the clinical outcomes of oral supplementation with curcumin-phospholipid in addition to hyaluronic acid-based tear substitute for the management of dry eye disease (DED). Patients with a diagnosis of DED confirmed by pathological values of both NIKBUT <10 s. and OSDI Questionnaire score > 12 were included. Patients were randomized to receive 2 different treatments: 0.25% hyaluronic acid-based tear substitute 3 time daily (Group 1) or as above plus curcumin-phosphatidylcholine complex tablets once a day (Group 2). Patients were evaluated at baseline (T0) and after 90 days of treatment (T1) by means of Keratograph for the measurement of NIKBUT, TMH, meibomian gland dropout and bulbar redness. Overall, data from 90 eyes of 45 patients were included. Group 1 consisted of 48 eyes of 24 patients, while group 2 included 42 eyes of 21 patients. When comparing median values of both groups at T0, no statistically significant differences were found for all parameters; instead for T1, statistically significant differences were found for redness and OSDI compared to Group 1. In group 1, a statistically significant reduction after the treatment was detected for Nikbut average and OSDI questionnaire; while in group 2, a statistically significant reduction after treatment was recorded for Nikbut average, bulbar redness and OSDI questionnaire. The addition of an oral supplement containing curcumin-phospholipid may help in a greater improvement of bulbar redness and subjective ocular symptoms compared to the treatment with tear substitutes alone for the management of DED

Actuation of Micro-Optomechanical Systems Via Cavity-Enhanced Optical Dipole Forces

We demonstrate a new type of optomechanical system employing a movable, micron-scale waveguide evanescently-coupled to a high-Q optical microresonator. Micron-scale displacements of the waveguide are observed for milliwatt(mW)-level optical input powers. Measurement of the spatial variation of the force on the waveguide indicates that it arises from a cavity-enhanced optical dipole force due to the stored optical field of the resonator. This force is used to realize an all-optical tunable filter operating with sub-mW control power. A theoretical model of the system shows the maximum achievable force to be independent of the intrinsic Q of the optical resonator and to scale inversely with the cavity mode volume, suggesting that such forces may become even more effective as devices approach the nanoscale.Comment: 4 pages, 5 figures. High resolution version available at (http://copilot.caltech.edu/publications/CEODF_hires.pdf). For associated movie, see (http://copilot.caltech.edu/research/optical_forces/index.htm

Feasibility of detecting single atoms using photonic bandgap cavities

We propose an atom-cavity chip that combines laser cooling and trapping of neutral atoms with magnetic microtraps and waveguides to deliver a cold atom to the mode of a fiber taper coupled photonic bandgap (PBG) cavity. The feasibility of this device for detecting single atoms is analyzed using both a semi-classical treatment and an unconditional master equation approach. Single-atom detection seems achievable in an initial experiment involving the non-deterministic delivery of weakly trapped atoms into the mode of the PBG cavity.Comment: 11 pages, 5 figure

From Vineyard to Vision: Efficacy of Maltodextrinated Grape Pomace Extract (MaGPE) Nutraceutical Formulation in Patients with Diabetic Retinopathy

Despite recent advances, pharmacological treatments of diabetic retinopathy (DR) do not directly address the underlying oxidative stress. This study evaluates the efficacy of a nutraceutical formulation based on maltodextrinated grape pomace extract (MaGPE), an oxidative stress inhibitor, in managing DR. A 6-month, randomized, placebo-controlled clinical trial involving 99 patients with mild to moderate non-proliferative DR was conducted. The MaGPE group showed improvement in best-corrected visual acuity (BCVA) values at T3 (p < 0.001) and T6 (p < 0.01), a reduction in CRT (at T3 and T6, both p < 0.0001) and a stabilization of vascular perfusion percentage, with slight increases at T3 and T6 (+3.0% and +2.7% at T3 and T6, respectively, compared to baseline). Additionally, the levels of reactive oxygen metabolite derivatives (dROMs) decreased from 1100.6 ± 430.1 UCARR at T0 to 974.8 ± 390.2 UCARR at T3 and further to 930.6 ± 310.3 UCARR at T6 (p < 0.05 vs. T0). Similarly, oxidized low-density lipoprotein (oxLDL) levels decreased from 953.9 ± 212.4 μEq/L at T0 to 867.0 ± 209.5 μEq/L at T3 and markedly to 735.0 ± 213.7 μEq/L at T6 (p < 0.0001 vs. T0). These findings suggest that MaGPE supplementation effectively reduces retinal swelling and oxidative stress, contributing to improved visual outcomes in DR patients

Mechanisms of Degradation and Identification of Connectivity and Erosion Hotspots

The context of processes and characteristics of soil erosion and land degradation in Mediterranean lands is outlined. The concept of connectivity is explained. The remainder of the chapter demonstrates development of methods of mapping, analysis and modelling of connectivity to produce a spatial framework for development of strategies of use of vegetation to reduce soil erosion and land degradation. The approach is applied in a range of typical land use types and at a hierarchy of scale from land unit to catchment. Patterns of connectivity and factors influencing the location and intensity of processes are identified, including the influence of topography, structures such as agricultural terraces and check dams, and past land uses. Functioning of connectivity pathways in various rainstorms is assessed. Modes of terrace construction and extent of maintenance, as well as presence of tracks and steep gradients are found to be of importance. A method of connectivity modelling that incorporates effects of structure and vegetation was developed and has been widely applied subsequently