Solution‐Processed Small‐Molecule Bulk Heterojunction Ambipolar Transistors

Solution‐processed small‐molecule bulk heterojunction (BHJ) ambipolar organic thin‐film transistors are fabricated based on a combination of [2‐phenylbenzo[d,d']thieno[3,2‐b;4,5‐b']dithiophene (P‐BTDT) : 2‐(4‐n‐octylphenyl)benzo[d,d ']thieno[3,2‐b;4,5‐b']dithiophene (OP‐BTDT)] and C₆₀. Treating high electrical performance vacuum‐deposited P‐BTDT organic semiconductors with a newly developed solution‐processed organic semiconductor material, OP‐BTDT, in an optimized ratio yields a solution‐processed p‐channel organic semiconductor blend with carrier mobility as high as 0.65 cm² V^?1 s^?1. An optimized blending of P‐BTDT:OP‐BTDT with the n‐channel semiconductor, C₆₀, results in a BHJ ambipolar transistor with balanced carrier mobilities for holes and electrons of 0.03 and 0.02 cm² V^?1 s^?1, respectively. Furthermore, a complementary‐like inverter composed of two ambipolar thin‐film transistors is demonstrated, which achieves a gain of 115.     

Composite polymeric microsponge-based long-acting gel formulation for topical delivery of mupirocin

Topical delivery of medicaments in a controlled manner is still a promising area of research. Drug-containing dammar gum-ethyl cellulose composite microsponge loaded gel formulation (D-MSPG) was developed for controlled topical delivery of mupirocin. The drug-loaded microsponges (D-MSPs) were formulated by the quasi-emulsion solvent diffusion method and were evaluated for morphology, particle size distribution, entrapment efficiency, thermal properties, and crystallinity. The optimized D-MSPs (entrapment efficiency 91.5 ± 4.0% and particle size of 55.15 ± 2.9 μm) were dispersed in carbopol 934 gel (D-MSPG). The final product was characterized for pH, viscosity, texture, spreadability, consistency, syneresis, in vitro drug release, and ex vivo skin penetration study. A comparative study with marketed formulation was performed. For optimized gel formulation (G4), drug content was 104.19 ± 1.68%, and drug release was 84.19% after 24 h. The pH of the optimized gel was observed to be 6.05 ± 0.04. Viscosity of the optimized gel formulation was found to be 1212.15 ± 434.85 mPa-s at 50 s⁻¹. The steady-state flux (J) in ex vivo skin permeation was observed to be 53.96 μg cm⁻² h⁻¹ and the permeability coefficient was 2.69 cm/h for the optimized gel formulation. According to the findings, the D-MSPG-based formulation strategy can act well to prolong the topical delivery of mupirocin or similar drug molecules.     

Erosion/corrosion data handling for reliable NDE

Ruptures in wet-steam and single-phase water lines at fossil and nuclear plants due to erosion/corrosion of of the inside surface have resulted in comprehensive measurement of wall thickness of components prone to failure. The large number of components to be inspected as well as the required resolution to make that inspection require effective management of the large amounts of ultrasonic testing data. Recognizing this need, Northern States Power (NSP) Company initiated compilation and organization of a database which contained inspection history, component type and history, flow conditions in the component along with detailed wall thickness measurements. The database was organized using a commercially available personal computer (PC)-based database management software package.This paper discusses the background of erosion/corrosion (E/C) damage at U.S. utilities; the industry response; NDE approaches to wall thinning examination; and practical techniques used to analyze wall thickness data from components and compare data between inspection intervals. The data were compiled from nuclear and fossil units.     

Impedance spectroscopy of CuO-doped Y-TZP ceramics

The effects of CuO additions on the grain interior and grain boundary resistivity in coated 2.5 mol% Y-TZP ceramics have been studied by using impedance spectroscopy. In addition, the effects of hydrothermal ageing on the conductivities of the ceramics were evaluated. The results showed that the grain interior and grain boundary resistivities increased with increasing CuO content. In particular, the grain boundary resistivity was observed to increase significantly in the doped ceramics, which could have been due to the formation of compounds, and resulted in lower conductivity. Impedance spectroscopy performed on the hydrothermally aged Y-TZPs revealed that the grain boundary regions were significantly affected, i.e. the grain boundary resistivities of the undoped and CuO-doped samples were increased by 65% and 45% respectively after ageing for 200 h.Thus, the indication is that the ageing-induced tetragonal to monoclinic phase transformation is closely associated with changes in the grain boundary regions.     

SAR CHARACTERIZATION OF FOCUSED PLANAR ARRAY OF WATER-LOADED MODIFIED BOX-HORNS FOR HYPERTHERMIA

A 4×4 planar array of modified box-horns as a microwave hyperthermia applicator is theoretically studied to characterize power deposition (SAR) in heating tissue (muscle) at 2450 MHz. A modified box-horn is a novel improved version of conventional box-horn in which horn exciting the box waveguide is flared in both E-and H-planes. Modified box-horn supports TE₁₀ and TE₃₀ modes. The amplitude distribution over the H-plane of the box-horn aperture is a closer approximation to the uniform distribution. It is proposed that the interior of the box-horn be filled with water to provide a better impedance match to biological tissue. By applying Fresnel-Kirchhoff scalar diffraction field theory, the expression for electric field in heating region is derived and distribution of specific absorption rate (SAR) in that region due to planar array of modified box-horns as direct contact applicator is evaluated at 2450 MHz. The results of modified box-horn array are compared with those of a single modified box-horn operating at the same frequency. Results demonstrate that planar array of modified box-horns offers improvement in SAR distribution and penetration depth. It is shown that by changing the phase and amplitude of excitation of the modified box-horns of the array, the relative amplitude and position of the hot spot can be changed. The present analysis is validated through the results obtained by plane wave spectral technique.     

Thermal characterization of materials at high pressures

This review deals with the development of some novel techniques for the measurement of thermal properties of materials at ambient and high pressures. Thermal characterization techniques like Absolute thermoelectric—power, AC electrical Resistivity, Differential thermal analysis and AC Calorimetry with specific reference to their usage at high pressures will be discussed in some detail. Some typical data on materials like Chromium alloys, Chalcogenide and metallic glasses will be presented.     

Planar nanogrinding of a fine grained WC-Co composite for an optical surface finish

Nanogrinding of a fine-grained WC-Co composite was developed to achieve an optical quality surface without further polishing. Direct planar grinding was conducted with a CNC grinding machine using a metal-bond diamond wheel of grit size of 15 μm, under the nanogrinding conditions selected. The ground planar surfaces were examined using laser and optical interferometry, atomic force microscopy, and scanning electron microscopy to measure flatness, surface roughness, and surface integrity as a function of grinding conditions. Damage-free, planar mirror surfaces with a flatness (peak-to-valley, PV) at the submicron scale and surface roughness <5 nm R_a were obtained.     

Single‐polymer composites based on slowly crystallizing polymers

An approach of using slowly crystallizing polymers to form single‐polymer composites (SPCs) was investigated. The method was demonstrated using poly(ethylene terephthalate) (PET) as a model system, with which two distinct physical forms, namely, amorphous PET films and highly crystalline PET fibers can be readily obtained. Because of the large difference between the rubbery softening temperature of the amorphous phase and the melting temperature of the crystalline phase, the new process is characterized by its wide process window and enhanced manufacturability. The heating temperature and holding time were found to play a profound role in influencing the properties of the SPC. Excellent fiber–matrix interfacial adhesion was obtained at heating temperature 180°C and holding time 10 s. The results also indicated that the heating rate plays a significant role in affecting the fusion and adhesion of the composite. With reduced heating rates, the fusion and adhesion properties are rapidly deteriorated. POLYM. ENG. SCI., 46: 1223–1230, 2006. © 2006 Society of Plastics Engineers     

Use of wheel speed as a parameter to inhibit surface crack generation in the grinding of wear-resistant fillers

At periodic intervals, aerospace engine parts undergo a refurbishment process to maintain stringent quality requirements. This process uses hard composite wear-resistant materials, which impose serious machining challenges particularly in overcoming surface damages. As a result, the process needs to be frequently interrupted for tool-sharpening and other preparation processes. This paper addresses one such issue for LPT vane blades and introduces high wheel speed as a parameter to overcome surface damage and to improve process efficiency . An erratum to this article is available at .