Developing chromic dyeable PET nanocomposites: The dye absorption and complex formation mechanisms

This research aimed to investigate the possibility of enhancement of polyethylene terephthalate (PET) dyeability using nanotechnology. Different kinds of disperse, acidic, and chromic dyes were used for dyeing of produced PET/silver nanocomposite fine multifilament yarns produced at the take up speeds of 3000 m min⁻¹ and their prepared fabrics. Dyeability improved by using acidic dyes. However, the more promotion effect was achieved by chromic dyes. No effect on absorption of disperse dyes revealed that no physical effect can be considered for dye absorption. The electrostatic interaction between silver and acidic dye molecules and forming the coordinative bonds with chromic dye molecules on nanocomposite yarns and fabrics were concluded and thoroughly discussed. Applying chromic dye with the more potential of creating coordinative bonds intensified the improvement of dyeability. Optimized silver ratio for the dyeability enhancement was affected by the mechanisms of dye absorptions discussed and proven by investigating dye concentrations in the effluent baths after the dyeing processes. It has been found that the steric hindrance is the key factor for absorption of chromic dyes; however, it is different in the case of acidic dyes, well discussed according to the dye absorptions mechanisms. The results can be also considered as evidence to prove forming the coordinative bonds with chromic dye molecules. This has also been confirmed by appearing a bathochromic shift in the absorption peaks by increasing dyeability using chromic dye. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Structural and electronic properties of C and BN nanotubes based on periodic fullerenes: A density functional theory study

The structural and electronic properties of C and BN nanotubes based on periodic fullerenes were studied using density functional theory. It was shown that these tubular structures are stable. The electronic band structures and density of states indicated that the C nanotubes based on periodic fullerenes are metals. The energy band gap was appeared by substitution of C atoms with B and N atoms. The BN nanotubes based on periodic fullerenes show semiconducting properties. Our results suggest that the nanotubes based on periodic fullerenes can be used to design of nanoelectronic devices.     

Evaluation of Composition-Dependent Collection Efficiencies for the Aerodyne Aerosol Mass Spectrometer using Field Data

In recent years, Aerodyne aerosol mass spectrometers (AMS) have been used in many locations around the world to study the size-resolved, nonrefractory chemical composition of ambient particles. In order to obtain quantitative data, the mass or (number) of particles detected by the AMS relative to the mass (or number) of particles sampled by the AMS, i.e., the AMS collection efficiency (CE) must be known. Previous studies have proposed and used parameterizations of the AMS CE based on the aerosol composition and sampling line relative humidity. Here, we evaluate these parameterizations by comparing AMS mass concentrations with independent measurements of fine particle volume or particle-into-liquid sampler (PILS) ion chromatography measurements for 3 field campaigns with different dominant aerosol mixtures: (1) acidic sulfate particles, (2) aerosol containing a high mass fraction of ammonium nitrate, and (3) aerosol composed of primarily biomass burning emissions. The use of the default CE of 0.5 for all campaigns resulted in 81–90% of the AMS speciated and total mass concentrations comparing well with fine particle volume or PILS measurements within experimental uncertainties, with positive biases compared with a random error curve. By using composition-dependent CE values (sometimes as a function of size) which increased the CE for the above aerosol types, the fraction of data points within the measurement uncertainties increased to more than 92% and the mass concentrations decreased by ～5–15% on an average. The CE did not appear to be significantly dependent on changes in organic mass fraction although it was substantial in the 3 campaigns (47, 30, and 55%).

Copyright 2012 American Association for Aerosol Research     

Oxidative polymerization of 3,4-ethylenedioxythiophene using transition-metal tetrasulfonated phthalocyanine

A method for the synthesis of water-soluble polyethylenedioxythiophene (PEDOT) by using transition-metal tetrasulfonated phthalocyanine (TSPc) and hydrogen peroxide as effective catalysts in the presence of sulfonated polystyrene (SPS) is reported. The reactions were carried out with different catalysts, such as iron, cobalt and manganese phthalocyanine. Metallophthalocyanines have shown good activities for polymerization, although they degraded easily under oxidizing conditions. In order to determine the role of pH during the polymerization, the reaction was carried out under different pH conditions 2, 2.5 and 3 and the best results were obtained at pH 2. The conductivity of our product was obtained and compared with similar commercial material. PEDOT was characterized by UV–vis and FT-IR spectroscopies and also cyclic voltammetry. Cyclic voltammetry (CV) demonstrated that the synthesized polymer has convenient electroactivity.     

Characterization of boron-doped micro- and nanocrystalline diamond films deposited by wafer-scale hot filament chemical vapor deposition for MEMS applications

Micro- and nanocrystalline diamond (MCD and NCD) films are deposited on 4-inch silicon substrates by a large-area multi-wafer-scale hot filament chemical vapor deposition (HFCVD) system. The films are in-situ doped by boron. The chemical and crystalline structures are studied by electron probe microanalysis (EPMA), Raman spectroscopy and X-ray diffraction (XRD). The microcrystalline films have a preferred (111) texture, while the nanocrystalline films exhibit (220) texture. Strain gauges and cantilever beam arrays are micro-fabricated by surface micro-machining techniques to characterize the residual strain and strain gradient of the diamond films. Both micro- and nanocrystalline films have small compressive strains of − 0.052% and − 0.040% respectively, with the strain gradient of about 10^− 5 μm^− 1. These values are low enough to enable the realization of many MEMS devices.     

A scanning tunneling microscopy study of low-temperature grown GaAs

Scanning tunneling microscopy (STM) has been used to investigate the effect of low-temperature (LT) growth of GaAs by molecular beam epitaxy on the morphology of the resulting surface. We present STM images of a GaAs(001) surface that was grown at ∼300°C and subsequently annealed at 600°C and show that there is a recovery of the (2×4) reconstruction. We also report images of a surface grown on top of a buried LT GaAs layer and show that the LT layer has little effect on the resulting surface morphology. In addition, scanning tunneling spectroscopy spectra are presented which demonstrate that the current-voltage characteristics of annealed and unannealed LT grown GaAs are significantly different.     

Vapor phase anti-stiction coatings for MEMS

Due to their large surface-area-to-volume ratio, most micromechanical devices are susceptible to adhesion, friction, and wear. Conventional approaches to abate the deleterious effects of adhesion and friction rely on the deposition of organically based anti-stiction monolayers produced from liquid phase processes. It has become widely accepted that liquid phase monolayer processes are less desirable than vapor phase processes, especially for manufacturing purposes. Thus, current research is aimed at the development of vapor phase anti-stiction processes that yield comparable or better films than their corresponding liquid phase processes. To date, a variety of monolayer systems that have been well established via liquid phase deposition processes have been adapted to vapor processes. In this paper, current trends in anti-stiction technology and a discussion of available vapor phase anti-stiction methods are presented.     

Comparison of two inference methods for P-type fuzzy logic control through experimental investigation using a hydraulic manipulator

This paper presents a comparison of the two important inference schemes: “individual-rule-based inference” and “compositional rule of inference” as applied to fuzzy logic control, through experimental investigation. The techniques are implemented on a hydraulic manipulator of an industrial machine with P-type fuzzy control. The fuzzy logic controller is designed for automatic positioning of the cutter blade of an automated fish-cutting machine. The features of the machine, which uses hydraulic servo control for cutter positioning, are outlined. The performance of the machine under the two inference schemes is examined and contrasted. Some practical implementations of the results are indicated.     

Synthesis,characterization, and measurement of structural,optical, and phtotoluminescent properties of zinc sulfide quantum dots

A facile and rapid microwave irradiation method was developed to prepare ZnS nanoparticles (NPs) using a set of ionic liquids (ILs) based on the bis(trifluoromethylsulfonyl) imide anion and different cations of 1-alkyl-3-methyl-imidazolium. The phases, structures, and optical absorption properties of the NPs were determined in depth with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, UV–vis absorption spectroscopy (UV–vis), diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The average crystallite size of the ZnS NPs calculated from the XRD pattern was of the order of 2.8 nm which exhibits cubic zinc blende structure. The energy band gap measurements of NPs were carried out by UV and DRS. The results revealed that the ZnS NPs exhibit strong quantum confinement effect. The optical band gap energy increases significantly compared with those of the bulk ZnS. The refractive indices for different ZnS nanosamples and different concentrations of ZnS NPs for a typical sample suspended in deionized water were also measured.     

CCN spectra, hygroscopicity, and droplet activation kinetics of secondary organic aerosol resulting from the 2010 Deepwater Horizon oil spill

Secondary organic aerosol (SOA) resulting from the oxidation of organic species emitted by the Deepwater Horizon oil spill were sampled during two survey flights conducted by a National Oceanic and Atmospheric Administration WP-3D aircraft in June 2010. A new technique for fast measurements of cloud condensation nuclei (CCN) supersaturation spectra called Scanning Flow CCN Analysis was deployed for the first time on an airborne platform. Retrieved CCN spectra show that most particles act as CCN above (0.3 ± 0.05)% supersaturation, which increased to (0.4 ± 0.1)% supersaturation for the most organic-rich aerosol sampled. The aerosol hygroscopicity parameter, κ, was inferred from both measurements of CCN activity and from humidified-particle light extinction, and varied from 0.05 to 0.10 within the emissions plumes. However, κ values were lower than expected from chemical composition measurements, indicating a degree of external mixing or size-dependent chemistry, which was reconciled assuming bimodal, size-dependent composition. The CCN droplet effective water uptake coefficient, γ(cond), was inferred from the data using a comprehensive instrument model, and no significant delay in droplet activation kinetics from the presence of organics was observed, despite a large fraction of hydrocarbon-like SOA present in the aerosol.