Organic contaminants removal by oxygen ECR plasma

Recently electron cyclotron resonance (ECR) plasma have been explored for wafer cleaning applications, since it is known to do less damage to silicon surface than conventional plasma. Organic contaminants removal efficiency and plasma radiation damage of the ECR plasma cleaning have been investigated. In oxygen ECR plasma cleaning, the plasma exposure time needed to remove the organic contaminants on the silicon surface down to the detection limit is 40 s, but the one to reach the lowest surface roughness is 10 s. The leakage current level of the MOS capacitor made using the Si substrate exposed to oxygen ECR plasma for 40 s is 8 × 10⁻⁹ A. The optimum exposure time determined by considering the contaminants removal efficiency and the plasma radiation damage (or the leakage current level) is 40 s. Organic contaminants seem to be removed through both sputter-off mechanism by oxygen ion bombardment and evaporation mechanism by chemical reactions with excited oxygen atoms.     

Enhanced luminescent properties of Y3Al5O12:Tb,Ce phosphor prepared by spray pyrolysis

Yttrium aluminum garnet (YAG) particles doped with Tb³⁺ or double doped with Tb³⁺ and Ce³⁺ were prepared by spray pyrolysis and characterized by photo- and cathode-luminescence. It was tried to incorporate a broad band of Ce³⁺ activator into the line peaks of Tb³⁺ in YAG host without the reduction of emission intensity. Ce-codoped YAG:Tb particles showed a broad band emission due to the d-f transition of Ce³⁺ and a reduction in the intensity of emission peaks due to ⁵D₃-⁷F_j (j=3, 4, 5, 6) transition of Tb³⁺ when they were excited by the ultraviolet light of 270 nm. These results supported that an effective energy transfer occurs from Tb³⁺ to Ce³⁺ in YAG host. Codoping Ce³⁺ ions greatly intensified the excitation peak at 270 nm for the emission at 540 nm of Tb³⁺, which means that more lattice defects, involving in the energy absorption and transfer to Tb³⁺, are formed by the Ce³⁺ codoping. The finding gives a promising approach for enhancing the luminescence efficiency.     

Synthesis of some 2-substituted-thioxanthones

This paper presents the synthesis of 2-amino-, 2-acetamido- and 2-benzamidothioxanthones and their 10,10-dioxides.     

Parameter-setting-free harmony search algorithm

Various phenomenon-mimicking algorithms, such as genetic algorithm, simulated annealing, tabu search, ant colony optimization, and particle swarm optimization, have their own algorithm parameters. These parameters need to be skillfully assigned in order to obtain good results. It is burdensome, especially to novice users, to assign these parameters. The same is true for the harmony search algorithm which was inspired by music performance. Thus, this study proposes a novel technique to eliminate tedious and experience-requiring parameter assigning efforts. The new parameter-setting-free (PSF) technique which this study suggests contains one additional matrix which contains an operation type (random selection, memory consideration, or pitch adjustment) for every variable in harmony memory. Three examples illustrate that the PSF technique can find good solutions robustly.     

Effects of surfactant and molecular weight of polyol on grating formation and switching of holographic PDLC

The interposition of surfactants between polymer and liquid crystal (LC) droplets was theoretically predicted by the positive spreading coefficient (0 < λ₃₁) and utilized to interpret the morphology, grating formation kinetics, diffraction efficiency, and switching of the holographic polymer dispersed liquid crystal (HPDLC), prepared from various types (octanoic acid, poly oxyethylene octyl phenyl ether, and perfluoro‐1‐butanesulfonyl fluoride) and amounts (0–9 wt%) of surfactant and molecular weights of polyol (PPG). Regardless of the surfactant type, diffraction efficiency increased with the addition and increasing amount of surfactant, a tendency consistent with increasing value of spreading coefficient, which is determined by the formulations of grating formation. In contrast, diffraction efficiency showed a maximum with the polypropylene glycol (PPG) molecular weight. Surfactant effectively reduced the anchoring energy and electrically drove the film which otherwise was not driven. Overall, surfactant with greater λ₃₁ gave smaller droplet, greater diffraction efficiency, driving voltage, contrast ratio, and smaller response time. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation and characterization of branched and linear sulfonated poly(ether ketone sulfone) proton exchange membranes for fuel cell applications

Branched sulfonated poly(ether ketone sulfone)s (Br‐SPEKS) were prepared with bisphenol A, bis(4‐fluorophenyl)sulfone, 3,3′‐disodiumsulfonyl‐4,4′‐difluorobenzophenone, and THPE (1,1,1‐tris‐p‐hydroxyphenylethane), respectively, at 180 °C using potassium carbonate in NMP (N‐methylpyrrolidinone). THPE, as a branching agent, was used with 0.4 mol % of bisphenol A to synthesize branched copolymers. Copolymers containing 10–50 mol % disulfonated units were cast from dimethylsulfoxide solutions to form films. Linear sulfonated poly(ether ketone sulfone)s (SPEKS) were also synthesized without THPE. The films were converted from the salt to acid forms with dilute hydrochloric acid. A series of copolymers were studied by Fourier transform infrared, ¹H‐NMR spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. The ion‐exchange capacity (IEC), a measure of proton conductivity, was evaluated. The synthesized Br‐SPEKS and SPEKS membranes exhibit conductivities (25 °C) from 1.04 × 10^?3 to 4.32 × 10^?3 S/cm, water swell from 20.18 to 62.35%, IEC from 0.24 to 0.83 mequiv/g, and methanol diffusion coefficients from 3.2 × 10^?7 to 4.7 × 10^?7 cm²/S at 25 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1792–1799, 2008     

cis‐[(4R,5R)‐4,5‐Bis­(amino­methyl)‐2,2‐di­methyl‐1,3‐dioxolane‐N,N′](malonato‐O,O′)­platinum(II), an anticancer agent

In the title compound, [Pt(C₃H₂O₄)(C₇H₁₆N₂O₂)], the Pt atom is coordinated to two O and two N atoms in a square‐planar arrangement. The two independent mol­ecules, which have very similar structures, are approximately related by pseudo‐twofold screw‐axis symmetry. The six‐membered chelate ring in the leaving ligand assumes a conformation intermediate between the half‐chair and boat forms. The seven‐membered ring in the carrier ligand assumes a twist‐chair conformation and the oxolane ring assumes an envelope conformation. The crystal packing consists of extensive hydrogen‐bonding networks which form two‐dimensional molecular layers, and there are weak van der Waals interactions between these layers.     

Practical synthesis of (S)‐7‐(2‐isopropylamino)ethylcamptothecin hydrochloride,potent topoisomerase I inhibitor

A practical semi‐synthetic method of (S)‐7‐(2‐isopropylamino)ethylcamptothecin hydrochloride has been developed. The Mannich reaction of (S)‐7‐methylcamptothecin with isopropylamine hydrochloride in dimethyl sulfoxide as a formaldehyde source gave the desired product in moderate yield.     

Regional Absolute Quantification of the Neurochemical Profile of the Canine Brain: Investigation by Proton Nuclear Magnetic Resonance Spectroscopy and Tissue Extraction

The purpose of this study was to characterize the neurochemical profiles of various parts of the canine brain using proton nuclear magnetic resonance spectroscopy, tissue extraction, and external simulated phantom concentration quantification. The occipital, frontal, and temporal lobes, thalami, cerebellar cortices, and spinal cords of five pure bred adult beagles were collected, and heavy water solutions for the nuclear magnetic resonance sample were prepared using the methanol–chloroform–water extraction method. The metabolite concentrations in canine brain tissues were measured and compared with those found in human and rat brain tissues. In addition, the cross peaks of Lac, Glu/Gln, and mIns were identified using two-dimensional correlation spectroscopy in the canine frontal cortex. The present study demonstrated the absolute quantification of canine neuronal parts using in vitro high-resolution magnetic resonance spectroscopy, with tissue extraction used to accurately measure metabolite concentrations, thus providing valuable metabolic information regarding the various canine neuronal regions.