Synthesis and chemical properties of photoluminescent self-doped polyanilines

Fluorescent self-doped polyanilines (PAS-AntPy-a and PAS-AntPy-b) were obtained by the pyridinium sulfonation of poly(2-methoxyaniline-5-sulfonic acid) (PAS) with 4-(2-anthracene-9-yl-vinyl)pyridine (AntPy). The degrees of pyridinium sulfonation in PAS-AntPy-a and PAS-AntPy-b were 0.70 and 0.97, respectively. A neutral polyaniline with an AntPy side unit (PANI-AntPy) was synthesized by the oxidative polymerization of N-(2-aminophenyl)-4-(2-anthracene-9-yl-vinyl)pyridinium chloride. The UV-vis spectra of PAS-AntPy-a and PAS-AntPy-b exhibited an absorption due to the polaron band that was derived from the protonation of amine groups in the polyaniline backbone with the remaining sulfonic acid proton. In contrast, PANI-AntPy did not exhibit absorption due to the polaron band. PAS-AntPy-a, PAS-AntPy-b, and PANI-AntPy were photoluminescent in a solution. The electric conductivity of PAS-AntPy-a was σ = 1.5 × 10⁻⁷ S cm⁻¹, which was higher than that of H₂SO₄ doped PANI (4.2 × 10⁻⁹ S cm⁻¹) reported previously.     

Hydrogen reduction in GaAsN thin films by flow rate modulated chemical beam epitaxy

The amount of residual H in the GaAsN film grown by chemical beam epitaxy (CBE) can be decreased by flow rate modulation growth. Many H atoms in the films grown by CBE exist as N-H or N-H₂ structures. Although a higher growth temperature was required for decreasing the H concentration ([H]), it caused a decrease in the N concentration ([N]). A reduction in [H] while keeping [N] constant was necessary. By providing an intermittent supply of Ga source while continuously supplying As and N sources, [H] effectively decreased in comparison with the [H] value in the film grown at the same temperature by conventional CBE without reducing [N].     

An Si concentrator cell by single photolithography process

A mid-range concentrator cell by low-cost process is investigated and a new design is proposed. We tried to develop a single lithography CZ-Si cell process. The current conversion efficiency (not optimized) is 16% under X20 concentration without AR coating. The present moderate efficiency is possibly due to low bulk lifetime (approx. 5 μs after process). Cell efficiency and open-circuit voltage (V_oc) are expected to improve by using a better quality Si material and developing a low-stress process to maintain crystal quality. The equivalent circuit analysis reveals degradation of diode characteristics under concentration, which implies decline of fill-factor (FF) by use of low-quality concentrator optics.     

Simulation of solid deformation during solidification: Compression of a single dendrite

A method is developed to numerically simulate coupled solidification and deformation of dendrites. Dendritic solidification is modeled using the phase-field method. The elasto-viscoplastic deformation of the growing solid is computed using the material point method. The stress analysis assumes a sharp and stress free solid–liquid interface, with the zero contour line of the phase field used to identify the interface. The deformation-induced flow in the liquid is approximated through a zero-gradient extension of the deformation velocities in the solid. Changes in the crystallographic orientation angle and advection of the phase and temperature fields due to solid deformation are all accounted for. Numerous tests are performed to validate the various numerical procedures. The full model is then applied to simulate in two dimensions the compression of a single dendrite of a pure substance growing in an undercooled melt. The development of complex stress and strain distributions is observed. The deformations result in variations in the crystallographic orientation angle within the dendrite that, in turn, affect the subsequent solidification behavior. The modeling of the deformation of polycrystalline solidifying structures, including the formation of grain boundaries, is described in a companion paper.     

Cogging torque investigation of PM motors resulting from asymmetry property of magnetic poles: Influence of performance variation between permanent magnets

This paper examines the cogging torque of a permanent magnet (PM) motor resulting from the asymmetry property of magnetic poles, which comes from the performance variation between magnets. A PM motor with 32 poles (= 16 pole pairs) and 36 slots is selected for verification, because the motor whose pole/slot ratio is 8/9 is sensitive to the performance variation between permanent magnets. Assuming that two different magnetization levels of magnets are mixed together in one rotor, the amplitude of the 2.25th and 4.5th components of cogging torque, which show 36 (= 2.25 × 16) and 72 (= 4.5 × 16) times of pulsation per rotation respectively and both of which result from the asymmetry property of the magnetic poles, are evaluated. As a result, it is clarified that the cogging torque characteristics depend on the alignment pattern of the two kinds of magnets. The amplitudes of the 2.25th and 4.5th components of cogging torque are proportional respectively to the amplitude of the 36th and 72nd order harmonics of the squared magnetic flux density around the rotor which is set in the space without stator. Using the proportional constants found from the finite element analyses in some alignment patterns, the cogging torque amplitudes of the motors with other alignment patterns can be predicted by calculating the squared magnetic flux density around the rotor only. The predicted cogging torque amplitudes correspond to the actually calculated results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(3): 57– 67, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20669     

Study of an internal magnetic abrasive finishing using a pole rotation system: Discussion of the characteristic abrasive behavior

An internal magnetic abrasive finishing process using a pole rotation system was proposed to produce highly finished inner surfaces of workpieces used in critical applications. Previous research found that the process incorporating one of the characteristic behaviors of the abrasive, the jumbling of the abrasive, results in aggressive contact of the abrasive against the inner surface, disturbing the smooth surface finish. The aim of this paper, therefore, is to characterize the in-process abrasive behavior against the surface and its effects on the finishing characteristics and to describe the finishing mechanism. The magnetic force acting on the magnetic abrasive, controlled by the field at the finishing area, is considered the primary influence on the abrasive behavior against the inner surface of the workpiece. This study examines the relationships between the magnetic field, the force on the abrasive, and the abrasive behavior. The surface roughness and material removal measurements resulting from finishing experiments demonstrate the effects of the abrasive behavior on the surface modifications. This paper also proposes a method to monitor the in-process abrasive behavior to facilitate processing.     

Comparative study of the activity of nickel ferrites for solar hydrogen production by two-step thermochemical cycles

In this work, we compare the activity of unsupported and monoclinic zirconia – supported nickel ferrites, calcined at two different temperatures, for solar hydrogen production by two-step water-splitting thermochemical cycles at low thermal reduction temperature. Commercial nickel ferrite, both as-received and calcined in the laboratory, as well as laboratory made supported NiFe₂O₄, are employed for this purpose. The samples leading to higher hydrogen yields, averaged over three cycles, are those calcined at 700 °C in each group (supported and unsupported) of materials. The comparison of the two groups shows that higher chemical yields are obtained with the supported ferrites due to better utilisation of the active material. Therefore, the highest activity is obtained with ZrO₂-supported NiFe₂O₄ calcined at 700 °C.     

Superstructure in a Triclinic Phase of Tricalcium Silicate

A triclinic phase of tricalcium silicate (TI) was investigated using transmission electron microscopy (TEM). Electron diffraction patterns were analyzed by introducing a subcell with the cell parameters of a = 7.081 Å, b = 7.043 Å, c = 25.230 Å, α= 89.97°, β= 90.37°, and γ= 119.44°. It was proven that the coordinates of all the reflections can be expressed to be ha *+ kb *+ lc *± m /6( a *+ 2 b *+ 2 c *), where m = 0, 1, 2, and 3. The result indicates that the structure modulation in TI is a one-dimensional type with a structural modulation normal to (122). The modulated structure could be observed in a high-resolution TEM image as wavy contrast streaking parallel to the plane with an interval of six times the (122) spacing.     

Hepatocyte growth factor and fibroblast growth factor 2 are overexpressed after cerulein-induced acute pancreatitis

Competency assessments are a growing function of the consultation-liaison (C-L) psychiatrist. Such consultation requests often mask a variety of psychosocial issues that are a source of frustration to the referring physician responding to the pressures of the changing health care delivery system in the acute care setting. This study identifies the issues and the outcome of psychiatric consultation in these patients. The implications of this burgeoning role for the C-L psychiatrist are also explored.