Experimental characterization and numerical analysis of the 4H-SiC p-i-n diodes static and transient behaviour

Steady-state and turn-off switching characteristics of aluminium-implanted 4H-SiC p-i-n diodes designed for high current density operation, are investigated experimentally and by mean of numerical simulations in the 298-523 K temperature range. The diodes present circular structure with a diameter of 350 &#956;m and employ an anode region with an aluminium depth profile peaking at 6?1019 cm&#8722;3 at the surface. The profile edge and the junction depth are located at 0.2 and 1.35 &#956;m, respectively. At room temperature the measured forward current density is close to 370 A/cm2 at 5 V with an ideality factor always less than 2 before high current injection or device series resistance became dominant. The transient analysis reveals a strong potential of this diodes for use in high speed, high power applications, especially at high temperature, with a very low turn-off recovery time (<80 ns) in the whole range of test conditions. The simulated results match the experimental data, showing that the switching performance is mainly due to the poor minority charge carrier lifetime estimated to be 15 ns for these implanted devices

All-optical modulation in a CMOS-compatible amorphous silicon-based device

Active silicon photonic devices, which dynamically control the flow of light, have received significant attention for their use in on-chip optical networks. High-speed active silicon photonic modulators and switches rely on the plasma dispersion effect, where a change in carrier concentration causes a variation in the refractive index. The necessary electron and hole concentration change can be introduced either by optical pumping, or by direct electrical injection and depletion. We demonstrate a fast photoinduced absorption effect in low loss hydrogenated amorphous silicon (a-Si:H) waveguides deposited at a temperature as low as 190°C. Significant modulation (M% ~90%) occurs with a 1 mm-long device. We attribute the enhanced modulation to the significantly larger free-carrier absorption effect of a-Si:H. The complementary metal-oxide semiconductor (CMOS) compatible technology of a-Si:H could be considered as a promising candidate to enable an easy back-end integration with standard microelectronics processes

Some Considerations on the Behaviour of Bolted Stainless-Steel Beam-to-Column Connections: A Simplified Analytical Approach

Stainless-steel has proven to be a first-class material with unique mechanical properties for a variety of applications in the building and construction industry. High ductility, strain hardening, durability and aesthetic appeal are only a few of them. From a specific point of view, its nonlinear stress–strain behaviour appears capable of providing a significant increase in the rotational capacity of stainless-steel connections. This, in turn, may provide significant benefits for the overall response of a structure in terms of capacity and ductility. However, the bulk of the research on stainless-steel that has been published so far has mostly ignored the analysis of the deformation capabilities of the stainless-steel connections and has mostly focused on the structural response of individual members, such as beams or columns. For such a reason, the present study aims to contribute to the general understanding of the behaviour of stainless-steel connections from a conceptual, numerical and design standpoint. After a brief review of the available literature, the influence of the use of stainless-steel for column–beam connections is discussed from a theoretical standpoint. As a novel contribution, a different approach to compute the pseudo-plastic moment resistance that takes into account the post-elastic secant stiffness of the stainless-steel is proposed. Successively, a refined finite element model is employed to study the failure of stainless-steel column–beam connections. Finally, a critical assessment of the employment of carbon-steel-based design guidelines for stainless-steel connections provided by the Eurocode 3 design (EN 1993-1-8) is performed. The findings prove the need for the development of novel design approaches and more precise capacity models capable of capturing the actual stainless-steel joint response and their impact on the overall ductility and capacity of the whole structure

Policaptil Gel Retard in adult subjects with the metabolic syndrome: Efficacy, safety, and tolerability compared to metformin.

Abstract Background Policaptil Gel Retard® (PGR), is a new macromolecule complex based on polysaccharides slowing the rate of carbohydrate and fat absorption. It proved to significantly reduce body weight, acanthosis nigricans expression, HbA1c levels, and glucose metabolism abnormalities in obese, hyper-insulinemic adolescents. No such data are available for adults. Aim to compare the effects of PGR vs. metformin in adult subjects with the Metabolic Syndrome (MS) and T2DM on a Low Glycemic Index diet. Subjects and methods This spontaneous clinical, longitudinal, single-blind, randomized study based on a per-protocol analysis enrolled 100 outpatients with MS and T2DM consecutively referring to our clinic for three months, and randomly assigned to either the active treatment (Group A:, 6 tablets/day) or the comparator (Group B: Metformin tablets, 1500–2000 mg/day in two divided doses during the two main meals, to minimize side effects) to be taken 30 min before each main meal in equally divided doses. Serum lipid profile, anthropometry, HOMA-IR index, and tolerability parameters were evaluated before and after a 6-month follow-up period. Results all parameters improved at a similar rate in both groups but for the lipid profile, which got even better in Group A. Group A also experienced less prominent gastrointestinal side effects than its counterpart. Conclusion For the first time, we showed the non-inferiority of PGR compared to metformin in obese adult subjects with the MS and T2DM as for glycemic control and a clear-cut superiority of PGR in terms of both serum lipid-lowering capacity and tolerability

Electro-optical modulating multistack device based on the CMOS-compatible technology of amorphous silicon

In this paper we report results on a field-effect induced light modulation at λ = 1.55 um in a high-index-contrast waveguide based on a multisilicon-on-insulator (MSOI) platform. The device is realized with the hydrogenated amorphous silicon (α-Si:H) technology and it is suitable for monolithic integration in a CMOS Integrated Circuit. The device exploits the free carrier optical absorption electrically induced in the semiconductor core waveguide. The dynamic behaviour of the device was experimentally and theoretically analyzed in presence of a visible illumination showing a link between the photogeneration and the free carriers provided by doped α-Si:H layers. The core waveguide contains several thin dielectric films of amorphous silicon carbonitride (α-SiCN) embedded along its thickness highly enhancing the absorbing action of the modulator held in the on-state

The Natriuretic Peptide System: A Single Entity, Pleiotropic Effects

In the modern scientific landscape, natriuretic peptides are a complex and interesting network of molecules playing pleiotropic effects on many organs and tissues, ensuring the maintenance of homeostasis mainly in the cardiovascular system and regulating the water-salt balance. The characterization of their receptors, the understanding of the molecular mechanisms through which they exert their action, and the discovery of new peptides in the last period have made it possible to increasingly feature the physiological and pathophysiological role of the members of this family, also allowing to hypothesize the possible settings for using these molecules for therapeutic purposes. This literature review traces the history of the discovery and characterization of the key players among the natriuretic peptides, the scientific trials performed to ascertain their physiological role, and the applications of this knowledge in the clinical field, leaving a glimpse of new and exciting possibilities for their use in the treatment of diseases

CORRELATION BETWEEN MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Al-Si CAST ALLOYS

The influence of microstructure and process history on mechanical behaviour of cast Al-Si alloys is reported.In the present work, the EN-AC 46000 and 46100 aluminium alloys have been gravity cast using a stepbarpermanent mould, with a range of thickness going from 5 to 20 mm. Metallographic and image analysistechniques have been used to quantitatively examine the microstructural parameters of the ?-Al phaseand eutectic Silicon. Microstructure has been also correlated with the results coming from the numericalsimulation of the casting process. The results show that SDAS and length of eutectic silicon particles increasewith section thickness, and consequently mechanical properties decrease

Low-loss amorphous silicon waveguides grown by PECVD on indium tin oxide

Low-loss hydrogenated amorphous silicon (α-Si:H) waveguides were realized by plasma enhanced chemical vapour deposition (PECVD) on a transparent conductive oxide (TCO) layer which is intended to provide the buried contact for the application of an external bias in active devices, e.g. switches and modulators. In particular we propose a technological solution to overcome both the strong reduction in optical transmittance due to the very high extinction coefficient of metal contacts and, at the same time, the optical scattering induced by the texturization effect induced in α-Si:H films grown on TCO. The very high optical propagation losses were minimized by depositing a spin-on-glass (SOG) layer between the α-Si:H core-layer and the TCO bottom contact. In this case, propagation losses of 2.5 dB/cm at 1550 nm were measured. All the fabricated samples were optically characterized and the surface roughness was accurately measured using a mechanical profilometer. We observed that, for an α-Si:H core-layer directly deposited on the TCO contact, the surface roughness is of the order of 100 nm leading to totally opaque waveguides. The experimental performances have been compared to those obtained through calculations using an optical simulation package. The results are found to be in agreement with the experimental data

Electro-optically induced absorption in α-Si:H/α-SiCN waveguiding multistacks

Electro optical absorption in hydrogenated amorphous silicon (α-Si:H) – amorphous silicon carbonitride (α-SiCxNy) multilayers have been studied in two different planar multistacks waveguides. The waveguides were realized by plasma enhanced chemical vapour deposition (PECVD), a technology compatible with the standard microelectronic processes. Light absorption is induced at λ = 1.55 μm through the application of an electric field which induces free carrier accumulation across the multiple insulator/semiconductor device structure. The experimental performances have been compared to those obtained through calculations using combined two-dimensional (2-D) optical and electrical simulations