Microwave FinFET modeling based on artificial neural networks including lossy silicon substrate

Nowadays, FinFET represents a new and promising transistor structure for the aggressive downscaling of the CMOS technology. Typically, the small-signal modeling for FinFET is based on compact models or on equivalent circuit representations. As an alternative to such approaches, a small-signal behavioral model based on artificial neural networks is developed in this paper. Particular attention is devoted to modeling the low-frequency kinks of the scattering parameters, due to the lossy silicon substrate. The model is efficient and accurate, as confirmed by the comparison between measured and simulated microwave behavior.     

Synthesis and characterization of poly(2-hydroxyethyl methacrylate/itaconic acid) copolymeric hydrogels

In the present study poly(2-hydroxyethyl methacrylate-co-itaconic acid) (P(HEMA/IA)) hydrogels were synthesized by free-radical copolymerization of 2-hydroxyethyl methacrylate and itaconic acid in order to evaluate as controlled release drug delivery system. All polymerizations were performed in a mixture of water/ethanol with ethylene glycol dimethacrylate, as crosslinking agent, potassium persulfate, as initiator, and N, N, N′, N′-tetramethylethylene diamine, as activator. The samples were characterized by FTIR and SEM. Swelling kinetics and antibiotic release studies were performed using gravimetry and UV spectrophotometry, respectively. The antibacterial activity studies were performed bearing in mind that infections are the most common cause of biomaterial implant failure and represent a constant menace to the application of medical implants. The hemocompatibility testing was performed as imperative for medical devices intended for direct or indirect blood exposure. In accordance with the results of antibacterial assessment on gels loaded with antibiotics and hemolytic activity testing these gels exerted good bacterial growth inhibition and favorable hemolytic activity. The release profiles of antibiotics, evaluated in vitro conditions, were correspondent for antibacterial therapeutics. Therefore, it was concluded that (P(HEMA/IA)) gels could be propound for the potential application as drug delivery systems for the controlled release of antibiotics.     

Independent impact of thrombolytic therapy and vessel patency on left ventricular dilation after myocardial infarction. Serial echocardiographic follow-up

BACKGROUND: It has been shown that successful reperfusion of the infarct-related artery by thrombolysis can prevent left ventricular dilation after acute myocardial infarction; these beneficial effects were detected from several days to several months after infarction. To date, however, no study has shown that these effects can be demonstrated within hours after the onset of infarction. Furthermore, data are scarce on the independent impact of thrombolytic therapy and late vessel patency on ventricular volume and function. The aim of this study was to assess separate effects of thrombolysis and patency of the infarct-related artery on left ventricular size and function by serial two-dimensional echocardiographic examinations. METHODS AND RESULTS: We evaluated 131 consecutive patients with first acute myocardial infarction by two-dimensional echocardiography in the following sequence: days 1, 2, 3, 7, and after 3 and 6 weeks. Intravenous streptokinase was administered in 81 patients, and 50 patients were treated without thrombolysis. Left ventricular end-diastolic volume, end-systolic volume, and ejection fraction were determined from apical two- and four-chamber views using the Simpson biplane formula and normalized to body surface area. Coronary angiography was performed in 107 patients after a mean of 26.0 +/- 20.2 (mean +/- SD) days after infarction. Patency of the infarct-related artery was assessed using TIMI criteria, with 54 considered patent (TIMI 3) and 53 with TIMI grade < 3. On day 1, end-systolic volume was significantly higher in patients not receiving thrombolysis (37.7 +/- 15.3 versus 33.0 +/- 10.6 mL/m2, P = .045). End-systolic volume (ESVi) was significantly higher in patients treated without thrombolysis throughout the study, whereas significant differences in end-diastolic volume (EDVi) were detected from day 3 (P = .041) onward and in ejection fraction (EF) from day 2 (P = .025) onward, all differences becoming progressively more significant with time (6-week values: EDVi, 78.8 +/- 25.4 versus 65.9 +/- 15.7 mL/m2, P = .001; ESVi, 45.4 +/- 22.6 versus 33.9 +/- 15.1 mL/m2, P = .002; EF, 45.1 +/- 11.6% versus 50.2 +/- 10.1%, P = .018). Patients with an occluded infarct-related artery (TIMI < 3) demonstrated highly significant differences at 6 weeks compared with patients with patent vessels (EDVi, 76.8 +/- 24.7 versus 65.2 +/- 15.6 mL/m2, P = .006; ESVi, 44.6 +/- 23.3 versus 31.9 +/- 12.2 mL/m2, P = .001; EF, 45.0 +/- 11.6% versus 52.1 +/- 9.0%, P < .001), but these differences developed more slowly than that seen among the thrombolytic subgroups. Indeed, multivariate analysis demonstrated that thrombolysis was the major determinant of initial volumes (P = .08, .02, and .08 for EDVi, ESVi, and EF, respectively), while vessel patency was the overwhelming determinant of subsequent changes (P = .0033, .0002, and .0024 for EDVi, ESVi, and EF, respectively). Additionally, ventricular volumes were significantly higher and ejection fractions lower in patients with anterior versus inferior infarction, but even adjusting for these differences as well as those associated with age, sex, and initial ventricular volume, the additive and independent impact of thrombolysis and infarct vessel patency persisted. CONCLUSIONS: These data indicate that the beneficial effect of thrombolysis on left ventricular size and function can be demonstrated in the earliest phases of acute myocardial infarction and that subsequent changes are mediated primarily through patency of the infarct-related artery. Thrombolytic therapy and late vessel patency thus have an additive and complementary impact in reducing ventricular dilation after myocardial infarction.     

A study of pyrolysis of phenolic resin reinforced with carbon fibres and oxidized pan fibres

Pyrolysis of composites prepared from a phenol-formaldehyde resin and carbon fibres (CFRC) or oxidized PAN fibres (OFRC) has been investigated up to 1270 K. Two temperature regions can be distinguished in the pyrolysis of the CFRC: below 770 K the carbon fibres hold the composite structure resisting the tendency of the resin to produce composite shrinkage; above 770 K the CFRC volume and porosity abruptly increase due to a weakening of fibre/resin adhesion. During the pyrolysis of the OFRC a chemical reaction at the fibre/resin interface apparently takes place, beginning at 570 K and producing important changes in the material at 870–970 K. Somewhat smaller weight losses and markedly lesser shrinkage of the pyrolysed composite with respect to its separately treated components have been found. The fibres and the resin coalesce into a product having relatively high density and low porosity, the latter mainly consisting of narrow pores. Hydrogen content of the product is lower than that of the separately treated constituents. The reflections of both the resin and the oxidized PAN fibres are seen only in the X-ray patterns of the OFRC treated at low temperature, but above 670 K only the reflection due to the fibres appears. The interlayer spacing of the fibres in the composite is greater than in the fibres alone treated under the same conditions. According to the IR spectra, the CN groups and aromatic CH groups disappear from the composite at lower temperature than from its components treated separately.The existence of the reaction between the resin and the oxidized PAN fibres, leading to the destruction of the fibre materials, means that the co-carbonization product at 1270 K is not a composite and will not have the necessary mechanical properties. Therefore, this study must continue to look for fibres and matrices which are compatible during co-carbonization to 1270 K.     

Temperature‐dependent models of low‐noise microwave transistors based on neural networks

Neural networks are proposed for efficient temperature‐dependent modeling of small‐signal and noise performances of low‐noise microwave transistors over a wide temperature range. The proposed models can be based either on neural networks only or on a combination of neural networks and empirical transistor models. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

Pasta noodles enriched with sweet potato starch: Impact on quality parameters and resistant starch content

This research is focusing on the texture, rheology, and sensory properties of pasta products enriched with the sweet potato starch (SPS) as well as on the content of resistant starch (RS) in these products. SPS was extracted from orange sweet potatoes using 1 mol. L⁻¹ Sodium chloride solution. Durum wheat flour semolina was partially supplemented with 10, 20, and 30% (w/w) by SPS in the pasta formulation and the influence of enrichment on the cooking quality, mechanical and sensory properties, and the color was observed. SPS addition resulted in decreased water absorption and shorter dough development time, but the stability of the dough was also decreased. The optimum cooking time for pasta was reduced, but only slightly, on the other side, the swelling index increased, which negatively impacted on the firmness of the products. Increasing of the SPS content also resulted in higher stickiness values for pasta. When up to 20% of wheat flour was replaced, the color of finished products was less acceptable. In the products, the resistant and total starch content were determined. Pasta cooking resulted in the reduction of RS content, which was then increased by storing products for 24 hr. It can be concluded that the substitution of part of semolina flour with SPS increased the level of RS, but on the other side, it caused some significant differences from the quality of pasta made from semolina only.     

Preparation of TiO2/carbon nanotubes photocatalysts: The influence of the method of oxidation of the carbon nanotubes on the photocatalytic activity of the nanocomposites

A method for the preparation of efficient TiO₂/multi-wall carbon nanotubes nanocomposite photocatalysts by precipitation of anatase TiO₂ nanoparticles onto differently oxidized carbon nanotubes is presented. The precursor compound titanium(IV) bromide was hydrolyzed producing pure anatase phase TiO₂ nanoparticles decorated on the surface of the oxidized carbon nanotubes. The oxidative treatment of the carbon nanotubes influenced the type, quantity and distribution of oxygen-containing functional groups, which had a significant influence on the electron transfer properties, i.e., the photocatalytic activity of the synthesized nanocomposites. The results of C.I. Reactive Orange 16 photodegradation in the presence of all the synthesized nanocomposites showed their better photocatalytic activity in comparison to the commercial photocatalyst Degussa P-25.     

Bias-dependent hybrid PKI empirical–neural model of microwave FETs

Empirical models of microwave transistors based on an equivalent circuit are valid for only one bias point. Bias-dependent analysis requires repeated extractions of the model parameters for each bias point. In order to make model bias-dependent, a new hybrid empirical–neural model of microwave field-effect transistors is proposed in this article. The model is a combination of an equivalent circuit model including noise developed for one bias point and two prior knowledge input artificial neural networks (PKI ANNs) aimed at introducing bias dependency of scattering (S) and noise parameters, respectively. The prior knowledge of the proposed ANNs involves the values of the S- and noise parameters obtained by the empirical model. The proposed hybrid model is valid in the whole range of bias conditions. Moreover, the proposed model provides better accuracy than the empirical model, which is illustrated by an appropriate modelling example of a pseudomorphic high-electron mobility transistor device.