New concept of failure of thin organic films

A critical (steady state) value of the thermal expansion coefficients of different coatings was determined by a nondestructive technique (NDT) known as laser shearography. The behavior of organic coatings, i.e., ACE premium-grey enamel, a yellow acrylic lacquer, and a gold nail polish on a metallic alloy, i.e., a carbon steel, was investigated over a temperature range of 20–60 °C. The value of the thermal expansion coefficients of coatings was derived from the slope of the plot of the thermal deformation (strain) versus the applied temperature. The integrity of the coatings with respect to time was assessed by comparison the measured coefficients of thermal expansion (CTE) to the critical (steady state) or asymptotic value of CTE. By shearography, measurement of coating properties could be performed independent of parameters such as UV exposure, humidity, presence of chemical species, and other parameters which may normally interfere with conventional methods of the assessing of the integrity of coatings. Therefore, one may measure CTE of coatings, regardless of the history of the coating, in order to assess the integrity of coatings. Also, the obtained shearography data were found to be in a reasonable trend with the data of electrochemical impedance spectroscopy (EIS) in 3%NaCl solution.     

Gold,silver, and palladium nanoparticle/nano-agglomerate generation,collection, and characterization

Generation, collection, and characterization of gold, silver, and palladium nanoparticles and nano-agglomerates (collectively “nanoparticles”) have been explored. The nanoparticles were generated with a spark aerosol generator (Palas GFG-1000). They were collected using a deposition cell under diffusion and thermophoresis. The shapes and sizes of the deposited particles were measured using transmission electron microscopy (TEM). TEM images showed that the particles were in the range of 8–100 nm in diameter, and their shapes varied from nearly spherical to highly non-spherical. Thermophoresis enhanced the deposition of nanoparticles (over the diffusive or the isothermal deposition) in all cases. Further, the size distributions of the nanoparticles generated in the gas phase (aerosol) were measured using a scanning mobility particle sizer (SMPS 3080, TSI) spectrometer. The SMPS results show that an increase in the spark frequency of the generator shifted the size distributions of the nanoparticles to larger diameters, and the total particle mass production rate increased linearly with increase in the spark frequency. The computational fluid dynamics code Fluent (Ansys) was used to model the flow in the deposition cell, and the computed results conform to the observations.     

Modelling of optical absorption of silver NP’s produced by UV radiation embedded in mesostructured silica films

Hexagonal mesostructured films containing silver ions were obtained by sol–gel method. Brij 58 was used to produce channels into the film, which house these ions. The films were exposure to UV radiation to produced silver metallic nanoparticles. The presence of the metallic nanoparticles was determined by infrared spectroscopy and optical absorption. Besides, these nanoparticles and core–shell structures of silver–silver oxide nanoparticles were identified by high-resolution transmission electronic microscopy. From these measurements, the obtained size range for silver nanoparticles was 6.1 nm. The absorption spectrum located at 440 nm was modelled and well fitted with the Gans theory considering refractive index higher than the one coming from host matrix. This index is explained because the silver oxide shell modifies the local surrounding medium of the metallic nanoparticles.     

A carbon–LiFePO<Subscript>4</Subscript> nanocomposite as high-performance cathode material for lithium-ion batteries

A cathode material of an electrically conducting carbon–LiFePO₄ nanocomposite is synthesized by wet ball milling and spray drying of precursor powders prior to a solid-state reaction. The structural characterization shows that the composite is composed of LiFePO₄ crystals and 4.8 wt.% amorphous carbon. Galvanostatic charge/discharge measurements indicate that the composite exhibits a superior high energy and high cycling stability. This composite delivers a discharge capacity of 159.1 mAh g⁻¹ at 0.1 C, 150.8 mAh g⁻¹ at 1 C, and 140.1 mAh g⁻¹ at 2 C rate. The capacity retention of 99% is achieved after 200 cycles at 2 C. The 18,650 cylindrical batteries are assembled using the composite as cathode materials and demonstrate the capacity of 1,400 mAh and the capacity retention of 97% after 100 cycles at 1 C. These results reveal that the as-prepared LiFePO₄–carbon composite is one of the promising cathode materials for high-performance, advanced lithium-ion batteries directed to the hybrid electric vehicle and pure electric vehicle markets.     

Dielectric properties of thin-film ZrO<Subscript>2</Subscript> up to 50 GHz for RF MEMS switches

The dielectric properties of zirconium dioxide (ZrO₂) ceramic thin films were characterized up to 50 GHz using coplanar waveguides (CPWs) and metal–insulator–metal (MIM) capacitors with top circular electrodes. The ZrO₂ films were deposited using a chemical solution onto high-resistivity Si wafers and metal layers. The real part of the dielectric constant of approximately 22 and 26 was extracted at 50 GHz for CPW and MIM structures, respectively, and the loss tangent was approximately 0.09 at 50 GHz. C–V and I–V measurements were carried out to determine low-frequency and DC dielectric properties. The measurement results indicate that ZrO₂ is a promising material to be used as a dielectric layer for radio-frequency (RF) microelectromechanical systems (MEMS) capacitive switches.     

Magneto-electric response functions for simple atomic systems

We consider a simple atomic two-body bound state system that is overall charge neutral and placed in a static electric and magnetic field, and calculate the magneto-electric response function as a function of frequency. This is done from first principles using a two-particle Hamiltonian for both an harmonic oscillator and Coulomb binding potential. In the high frequency limit, the response function falls off as 1/ω ² whilst at low frequencies it tends to a constant value.     

An overview of quantification methods in energy-dispersive X-ray fluorescence analysis

This paper reviews the major factors influencing the accuracy of the energy-dispersive X-ray fluorescence (EDXRF) analysis including physical and chemical matrix effects (resulting from particle size, surface irregularity, mineralogy, moisture, absorption and enhancement) as well as the correction procedures with emphasis on the analysis of unprepared samples. Quantification methods for thin samples, samples with intermediate thickness and thick samples are presented including fundamental parameter methods, influence coefficient algorithms, empirical coefficient algorithms and quantification methods based on scattered primary radiation. Quality control procedures are also reviewed.     

Effects of surfactants on properties of polymer-coated magnetic nanoparticles for drug delivery application

The objective of this research was to compare the effects of two different surfactants on the physicochemical properties of thermo-responsive poly(N-isopropylacrylamide-acrylamide-allylamine) (PNIPAAm-AAm-AH)-coated magnetic nanoparticles (MNPs). Sodium dodecyl sulfate (SDS) as a commonly used surfactant in nanoparticle formulation process and Pluronic F127 as an FDA approved material were used as surfactants to synthesize PNIPAAm-AAm-AH-coated MNPs (PMNPs). The properties of PMNPs synthesized using SDS (PMNPs-SDS) and PF127 (PMNPs-PF127) were compared in terms of size, polydispersity, surface charge, drug loading efficiency, drug release profile, biocompatibility, cellular uptake, and ligand conjugation efficiency. These nanoparticles had a stable core–shell structure with about a 100-nm diameter and were superparamagnetic in behavior with no difference in the magnetic properties in both types of nanoparticles. In vitro cell studies showed that PMNPs-PF127 were more cytocompatible and taken up more by prostate cancer cells than that of PMNPs-SDS. Cells internalized with these nanoparticles generated a dark negative contrast in agarose phantoms for magnetic resonance imaging. Furthermore, a higher doxorubicin release at 40 °C was observed from PMNPs-PF127, and the released drugs were pharmacologically active in killing cancer cells. Finally, surfactant type did not affect the conjugation efficiency to the nanoparticles when folic acid was used as a targeting ligand model. These results indicate that PF127 might be a better surfactant to form polymer-coated magnetic nanoparticles for targeted and controlled drug delivery.     

Rectifying and photovoltage characteristics of Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>Co<Subscript>2</Subscript>O<Subscript>y</Subscript>/Nb-doped SrTiO<Subscript>3</Subscript> heterojunction

A heterojunction was fabricated by growing a layer of Bi₂Sr₂Co₂O _y thin film on the 0.7 wt% Nb-doped SrTiO₃ substrate. Such heterojunction showed good rectifying characteristics over a wide temperature range, and its transport mechanism under the forward bias can be attributed to a space charge limited conduction mechanism via defects near the interface of the heterojunction. Photovoltaic properties of the heterojunction were studied by using both continuous-wave and pulsed irradiations and the results can be well explained by the photovoltaic effect of a p–n junction.     

Single photon and nonlocality

In a paper by Home and Agarwal [1], it is claimed that quantum nonlocality can be revealed in a simple interferometry experiment using only single particles. A critical analysis of the concept of hidden variable used by the authors of [1] shows that the reasoning is not correct.