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

The Regulation of Rat Liver Xanthine Oxidase CONVERSION IN VITRO OF THE ENZYME ACTIVITY FROM DEHYDROGENASE (TYPE D) TO OXIDASE (TYPE O)

Abstract The aerobic oxidation of xanthine by rat liver supernatant was greatly stimulated by the addition of methylene blue or of NAD+: the latter was reduced during the reaction. Storage of the supernatant at -20° brought about an enhancement of the xanthine oxidation rate measured without addition of cofactors. A similar "activation" was caused by prior incubation at 37° of the unfractionated liver homogenate, or of the supernatant separated after sonic disruption of the homogenate. The same effect was obtained by treatment with solvents, or by prior incubation at 37° of the supernatant in the presence of proteolytic enzymes or under anaerobic conditions. The presence of xanthine accelerated the effect of proteolytic enzymes and of anaerobiosis. Only the changes caused by anaerobiosis could be reversed by incubating the supernatant in air before the assay. The reaction rate was apparently unaffected by these treatments if activity of the enzyme was measured in the presence of methylene blue or of NAD+. The latter, however, was not reduced during the oxidation of xanthine by "activated" supernatants stored at -20° if the reaction was run in the presence of oxygen. If the reaction was in anaerobiosis, uric acid and a corresponding amount of NADH were formed by fresh, supernatant, and by supernatants activated at -20° or by prior incubation in anaerobiosis, but not by supernatant activated by trypsin. The hypothesis is formulated that most of the xanthine oxidase of rat liver supernatant is a dehydrogenase (Type D), and may be converted (activated) into an oxidase (Type O)

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

Atherosclerosis and Its Related Laboratory Biomarkers

Atherosclerosis constitutes a persistent inflammatory ailment, serving as the predominant underlying condition for coronary artery disease (CAD), peripheral artery disease (PAD), and cerebrovascular disease. The progressive buildup of plaques within the walls of medium- and large-caliber arteries characterizes the atherosclerotic process. This accumulation results in significant narrowing that impedes blood flow, leading to critical tissue oxygen deficiency. Spontaneous blockage of thrombotic vessels can precipitate stroke and myocardial infarction, which are complications representing the primary global causes of mortality. Present-day models for predicting cardiovascular risk incorporate conventional risk factors to gauge the likelihood of cardiovascular events over a ten-year span. In recent times, researchers have identified serum biomarkers associated with an elevated risk of atherosclerotic events. Many of these biomarkers, whether used individually or in combination, have been integrated into risk prediction models to assess whether their inclusion enhances predictive accuracy. In this review, we have conducted a comprehensive analysis of the most recently published literature concerning serum biomarkers associated with atherosclerosis. We have explored the potential utility of incorporating these markers in guiding clinical decisions

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

Comparison of two disaster drills' management performed by trained and not-trained students: key times evaluation

Introduction The aim of this report is to compare two disaster exercises' management of students with different backgrounds. To our knowledge nobody has ever compared two exercises, probably because of the difficulty in their evaluation. We implemented a tool for an objective evaluation [1] and we used it for this purpose. Methods Both drills represented a ceiling collapse over a crowded room with a similar amount of casualties and similar severity index. The START triage system was used. The trained students (T) were attending the European Master in Disaster Medicine (EMDM), while the not-trained students (NT) were at the beginning of an introductory course in disaster medicine. During the exercises we recorded key victim-provider interaction times [2] using victim-based data collection. Each victim had their own data card to record triage and time information. Results In this preliminary report we present data regarding the scene length of stay (LOS) and triage to collecting area/advanced medical post time (T-AMP). The LOS was 67.5 (50.0 to 111.0) minutes (25 to 75 IQR) for T as compared with 145.0 (110.0 to 150.0) minutes (25 to 75 IQR) for NT (P < 0.001). Stratification according to assigned triage code showed no difference for high-priority codes (reds and yellows) as opposed to the green code (55.0 (47.0 to 75.0) minutes for T vs 145.0 (141.0 to 155.0) minutes for NT with P < 0.01). T-AMP was 10.0 (3.0 to 34.5) minutes for T as compared with 63.5 (19.5 to 104.3) minutes for NT (P < 0.001). Stratification according to triage code showed no difference for red codes between T and NT but showed a difference for yellow codes (36.5 (15.0 to 82.0) vs 71.0 (30.0 to 99.0) minutes) and green codes (7.0 (3.0 to 12.0) vs 85.0 (17.3 to 115.0) minutes) with P < 0.01. Conclusions Both teams evacuated red codes before the yellow ones in similar time. T-AMP was shorter considering global, yellow and green codes for T as opposed to NT. Global and green LOS was also shorter in the T group as opposed to NT. Training seems to influence global exercise management, less affecting red codes but with an impact on yellow and green evacuation strategies