Differences of behaviour in electrooxidation of 3,3′-dimethoxybenzidine and its N,N,N′,N′-tetraalkylated derivatives: a further example of potential inversion

The anodic oxidation of 3,3′-dimethoxybenzidine and its derivatives were studied by cyclic voltammetry, voltammetry at a rotating platinum electrode, chronopotentiometry and constant potential coulometry. The exhaustive oxidation of 3,3′-dimethoxybenzidine led at the potential of the first oxidation peak and second oxidation peak, respectively, to a stable cation radical salt (characterized by ESR spectroscopy) and to a quinone-diimine. Whereas, 3,3′-dimethoxy-N,N,N′,N′-tetramethylbenzidine afforded directly a dication salt owing to potential inversion 3,3′-dimethoxy-N,N,N′,N′-tetraethylbenzidine gave the corresponding soluble cation radical salt.     

Electromagnetic Design and Analysis of a Novel Axial-Transverse Flux Permanent Magnet Synchronous Machine

This paper analyzes a novel hybrid axial-transverse flux permanent magnet (PM) synchronous motor achieving high torque density. The stator pole pitch and the rotor pole pitch are the same. The motor is suitable for vehicle traction systems. The new axial-transverse machine has a single-sided or double-sided air gap. The machine has two adjacent quasi-U stator cores with ring-type winding, and the rotor has two PM groups, one outer and one inner. The shape of quasi-U stator core allows changing the flux path without changing power supply polarity. The analytical expressions of the no-load back-EMF and the torque are derived, after the development of 3-D magnetic equivalent circuit (MEC) model. The 3-D finite element method (FEM) is used to analyze the magnetic field, torque, and cogging torque for different skewings of the PMs.     

Novel thiophene symmetrical Schiff base compounds as corrosion inhibitor for mild steel in acidic media

The inhibiting effect of two Schiff bases on the corrosion of the mild steel (MS) in 1 M HCl has been studied by electrochemical impedance spectroscopy (EIS) and Tafel polarisation measurements. The Schiff bases, 4,4′-bis(3-carboxaldehyde thiophene) diphenyl diimino ether (L₁) and 4,4′-bis(3-carboxaldehyde thiophene) diphenyl diimino ethane (L₂), were synthesized using 3-carboxaldehydethiophene and its corresponding amine. Polarisation curves reveal that both compounds are mixed type (cathodic/anodic) inhibitors and inhibition efficiency (% IE) increases with increasing concentration of compounds. It is suggested that their effects depend on their concentrations and the molecular structures. Adsorption of compounds on mild steel surface is spontaneous and obeys Langmuir’s isotherm.     

Drain current model for undoped Gate Stack Double Gate (GSDG) MOSFETs including the hot-carrier degradation effects

In this paper, analytical models of drain current and small signal parameters for undoped symmetric Gate Stack Double Gate (GSDG) MOSFETs including the interfacial hot-carrier degradation effects are presented. The models are used to study the device behavior with the interfacial traps densities. The proposed model has been implemented in the SPICE circuit simulator and the capabilities of the model have been explored by circuit simulation example. The developed approaches are verified and validated by the good agreement found with the 2D numerical simulations for wide range of device parameters and bias conditions. GSDG MOSFET design and the accurate proposed model can alleviate the critical problem and further improve the immunity of hot-carrier effects of DG MOSFET-based circuits after hot-carrier damage.     

The bond and flexural strengthening of reinforced concrete elements strengthened with near surface mounted prestressing steel (PS) bars

Abstract

The main objective of this work is to study the performance of prestressing steel (PS) bars as reinforcements in the reinforced concrete (RC) elements strengthened by the near-surface mounted method (NSM). The work includes two parts. In the first part, direct pull-out tests are performed in order to study the bond performance between PS reinforcement and concrete. The influences of groove sizes and PS surface conditions (smooth and sand coated) are evaluated. The results show that the sand coated PS (PS-Sc) reinforcement has the best adhesion behavior compared with the smooth bar, and its pull-out force is increased by 48%. For this reason, the PS-Sc bars are used in the second part of this work as NSM reinforcement to strengthen RC beams subjected to bending forces. Then, four-point bending tests are carried out to understand the flexural behavior of strengthened RC beams with PS-Sc reinforcements of different lengths and ratios. The obtained results demonstrate that the use of NSM-PS-Sc bars strengthening technique leads to important enhancement in the load carrying capacity of the RC beams. The first crack load and ultimate load of the strengthened RC beams attain 71.41 and 65.67%, respectively, which are higher than those of the control beam. Furthermore, the experimental values show a good agreement with the analytical values in both the ultimate deflection and the ultimate load. This proves that the NSM-PS-Sc bars studied in this work are promising reinforcement of the RC beams.     

An approach based on particle swarm computation to study the electron mobility in wurtzite GaN

The properties of gallium nitride (GaN) make it a promising material for a variety of different electronic and optoelectronic devices. GaN has a wide direct bandgap and a resulting high breakdown field. Further progress in the development, design and optimization of GaN-based devices necessarily requires new theory and modeling techniques that capture the physics of electron transport accurately and efficiently. So, the objective of this work is to provide an optimized analytical model for low- and high-field electron mobility in wurtzite (hexagonal) GaN in wide temperature and concentration ranges basing on the particle swarm optimization (PSO) algorithm. A Monte Carlo transport simulations developed in this work has been evaluated and serve as the basis for the model development. The proposed model describes the dependence of the mobility on carrier concentration, temperature, and electric field. Good agreement between our results and measured data has been obtained. Thus, the presented mobility models can be used in device simulations to design and optimize different GaN device structures.     

Characteristic pathological associations in multiple endocrine neoplasia type 1

OBJECTIVES: Multiple endocrine neoplasia type 1 (MEN 1) is an inherited disorder characterised by slow progressing tumors of the parathyroids, of the endocrine pancreas and of the anterior pituitary. A genetic locus predisposing to this disease has been localised on chromosome 11. Predictive diagnosis of carriers of the defective gene is possible in families using genetic markers at this locus. However, this analysis presupposes a precise identification of affected subjects. Moreover, expression of the disease may vary from one family to the other. The aim of the present study was to define the typical clinical features of the syndrom. METHODS: We assessed retrospectively 26 cases of MEN 1 identified during 20 years in the same medico-surgical center. Among 11 men and 15 women, all those who had a genealogical investigation had a positive family history of MEN 1. RESULTS: Bifocal and trifocal tumors were the main patterns of associations, and were diagnosed at a mean age of 48.6 years. Parathyroid involvement was most frequent and earliest (96% of cases). The second most frequent was pancreatic involvement (69.2% of cases) predominantly manifesting with gastrinomas (N = 13). Multifocal tumors were usually diagnosed before or within 5 years following diagnosis of the first tumor. Among pituitary tumors one case of meningioma was observed, a feature not reported previously. An asymptomatic adrenal involvement was observed in about 1/3 of cases. Other silent tumors (euthyroid nodules, lipomas) were also noted. CONCLUSION: These data suggest that the clinical presentation and course of MEN 1 is homogeneous and are in agreement with the hypothesis of a recessive tumor-suppressor gene expressed in specific endocrine cell lines, suggesting that careful family studies should be conducted when a case of MEN 1 is diagnosed to facilitate early carrier detection among relatives.     

Subthreshold behavior optimization of nanoscale Graded Channel Gate Stack Double Gate (GCGSDG) MOSFET using?multi-objective genetic algorithms

In this paper, a multi-objective genetic algorithms-based approach is proposed to study and optimize the subthreshold behavior of Graded Channel Gate Stack Double Gate (GCGSDG) MOSFET for nanoscale CMOS digital applications. The subthreshold parameters such as threshold voltage, drain induced barrier lowering (DIBL), subthreshold swing and OFF-current have been ascertained and mathematical models have been proposed. The proposed mathematical models are used to formulate the objectives functions, which are the pre-requisite of genetic algorithm. The overall objective function is formulated by means of weighted sum approach. Thus, the proposed approach is used to search for optimal subthreshold parameters to obtain better electrical performances of the devices for digital application.