In situ environmental TEM studies of dynamic changes in cerium-based oxides nanoparticles during redox processes

We apply in situ environmental transmission electron microscopy (ETEM) to study the dynamic changes taking place during redox reactions in ceria and ceria-zirconia nanoparticles in a hydrogen atmosphere. For pure ceria, we find that a reversible phase transformation takes place at 730 degrees C in which oxygen vacancies introduced during reduction order to give a cubic superstructure with a periodicity of roughly twice the basic fluorite lattice. We also observe the structural transformations taking place on the surface during reduction in hydrogen. The (110) ceria surface is initially constructed with a series of low-energy (111) nanofacets. Under strong reduction, the surface slowly transforms to a smooth (110) surface which was not observed to change upon re-oxidation. The surface transformation allows the reduced surface to accommodate a high concentration of oxygen vacancies without creating a strong perpendicular dipole moment. In the ceria-zirconia system, we are able to use ETEM to follow the redox activity of individual nanoparticles and correlate this property with structure and composition. We find considerable variation in the redox activity and interpret this in terms of structural differences between the nanoparticles.     

New Amine Blends for Improved CO2 Separation: A Study on Reaction Kinetics and Vapor–Liquid Equilibrium

Gas cleaning will be more eco-friendly if the absorbents used for CO₂ capture are prepared from renewable supplies such as ethanol. Ethylene diamine (EDA), N-ethylmonoethanolamine (EMEA), N-ethyldiethanolamine (EDEA), and N,N′-diethylmonoethanolamine (DEMEA) represent this class of solvents. We selected two new blends from this group: EDEA?+?EMEA and DEMEA?+?EDA. Thus, a high-capacity tertiary amine (EDEA or DEMEA) was mixed with a very reactive amine (EMEA or EDA). Using a stirred cell, we analyzed kinetics of the CO₂ reaction with these blends in aqueous solutions (2–3?M) at 308?K. On the whole, two reactions ensued in parallel: one, between CO₂ and EDEA (or DEMEA), and the other, between CO₂ and EMEA (or EDA). We evidenced that DEMEA and DEMEA?+?EDA were more reactive than EDEA and EDEA?+?EMEA. We reported the rate constant for EMEA and EDA (4700 and 28,300?M^?1?s^?1). Finally, we presented vapor–liquid equilibrium data for the DEMEA?+?EDA blend.     

Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO

The search for ferromagnetism above room temperature in dilute magnetic semiconductors has been intense in recent years. We report the first observations of ferromagnetism above room temperature for dilute (<4 at.%) Mn-doped ZnO. The Mn is found to carry an average magnetic moment of 0.16 mu(B) per ion. Our ab initio calculations find a valance state of Mn(2+) and that the magnetic moments are ordered ferromagnetically, consistent with the experimental findings. We have obtained room-temperature ferromagnetic ordering in bulk pellets, in transparent films 2-3 microm thick, and in the powder form of the same material. The unique feature of our sample preparation was the low-temperature processing. When standard high-temperature (T > 700 degrees C) methods were used, samples were found to exhibit clustering and were not ferromagnetic at room temperature. This capability to fabricate ferromagnetic Mn-doped ZnO semiconductors promises new spintronic devices as well as magneto-optic components.     

Structural and optical properties of AlN/Si system

Aluminum nitride (AlN) is a wide band gap III–V semiconductor material which is often used for optical applications. Thin films of aluminum nitride were deposited by ion beam sputtering in an Ar–N₂ atmosphere on Si (1 0 0). For film preparation, the N₂ flow was kept at 5 sccm and the ratio of N₂ and Ar was 4:1. The films have been characterized by Grazing Incidence X-ray Diffraction (GIXRD), X-ray Reflectometry (XRR), Atomic Force Microscopy (AFM) and optical spectroscopy. GIXRD shows that the structure of the as-deposited sample of AlN is hexagonal. It is observed that neither the ion-beam-induced dissociation of the nitride film nor the enhanced nitrogen diffusion across the interface takes place after Au ion irradiation. XRR was used to determine the thickness of the films. The reflectance of the irradiated films increases in the range 200–280 nm. UV–vis spectra were taken in Kubelka Munk (KM) units for as-deposited and irradiated samples. The band gap was calculated for both types of samples, which shows that the band gap of irradiated films of aluminum nitride decreases due to the increase in metal content at the surface. AFM confirms that the roughness of aluminum nitride increases by irradiation.     

A novel approach using Dynamic Social Impact Theory for optimization of impedance-Tongue (iTongue)

This paper presents a novel multiobjective wrapper approach using Dynamic Social Impact Theory based optimizer (SITO). A Fuzzy Inference System in conjunction with support vector machines classifier has been used for the optimization of an impedance-Tongue for the classification of samples collected from single batch production of Kangra orthodox black tea. Impedance spectra of the tea samples have been measured in the range of 20 Hz to 1 MHz using a two electrode setup employing platinum and gold electrodes. The proposed approach has been compared, for its robustness and validity using various intra and inter measures, against Genetic Algorithm and binary Particle Swarm Optimization. Feature subset selection methods based on the first and second order statistics have also been employed for comparisons. The proposed approach outperforms the Genetic Algorithm and binary Particle Swarm Optimization.     

A new method for the synthesis of hydrophobic gold nanotapes

Protocols for the synthesis of gold nanoparticles are increasingly focusing on controlling the morphology of the nanocrystals. We demonstrate in this article the facile, one-step synthesis of gold nanotapes that are readily dispersible in organic media. This is accomplished by the spontaneous reduction of aqueous chloroaurate ions by hexadecylaniline molecules present in chloroform at the static interface between water and chloroform. The hexadecylaniline molecules cap the gold nanotapes thus formed, rendering them hydrophobic and dispersible in a range on nonpolar and weakly polar organic solvents. Possible reasons for the growth of gold nanotapes are discussed.     

Mechanism of self-assembled growth of ordered GaAs nanowire arrays by metalorganic vapor phase epitaxy on GaAs vicinal substrates

We report the self-catalyzed growth of GaAs nanowire arrays by metalorganic vapor phase epitaxy (MOVPE) on GaAs vicinal substrates. The effect of substrate misorientation on the nanowire growth and the influence of growth parameters such as temperature and input V/III ratio have been studied in detail. Variation in the nanowire growth mechanism and consequential changes in the nanowire growth morphology were observed. A VLS growth mechanism with negligible effect of the vicinal surface gave rise to randomly distributed droplet-terminated GaAs nanowires at 400?°C and multiprong root-grown GaAs nanowire clusters at 500?°C with low V/III ratio. The substrate misorientation effect was dominant at 500?°C with higher V/III ratio, in which case the combined effect of the vicinal surface and the self-catalyzed Ga droplets assisted the realization of self-assembled and crystallographically oriented epitaxial nanowire arrays through the vapor-solid mechanism.     

Enhanced cytotoxic activity of AgNPs on retinoblastoma Y79 cell lines synthesised using marine seaweed Turbinaria ornata

Retinoblastoma is the most common intraocular malignancy basically occurs among children below five. Certain ocular treatments such as surgery, radiation therapy and chemotherapy are more likely to cause side effects. Here, a rapid method of synthesising silver nanoparticles (AgNPs) from the brown seaweed Turbinaria ornata and its cytotoxic efficacy against the retinoblastoma Y79 cell lines was studied. The AgNPs synthesis was determined by Ultraviolet–visible spectroscopy and was further characterised by X‐ray diffraction, High‐resolution transmission electron microscopy, zeta potential, Energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, Fourier transform infrared spectrum and inductively coupled plasma‐mass spectroscopy techniques. The synthesised AgNPs were found to be very stable and finely dispersed. The total phenolic content of the synthesised AgNPs was estimated at 43±2.52 mg/g gallic acid equivalent and the nanoparticles exhibited good scavenging activity analysed by 2, 2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulphonic acid) assay. Moreover, cytotoxicity of synthesised AgNPs against in vitro retinoblastoma Y79 cell lines showed a dose‐dependent response with an inhibitory concentration (IC₅₀) of 10.5 µg/mL. These results suggest that AgNPs could be a promising anticancer agent with enhanced activity in ocular treatment.Inspec keywords: toxicology, silver, nanoparticles, cellular biophysics, cancer, nanomedicine, nanofabrication, X‐ray diffraction, transmission electron microscopy, electrokinetic effects, X‐ray chemical analysis, thermal analysis, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, biomedical materials, mass spectroscopic chemical analysisOther keywords: cytotoxic activity, marine seaweed Turbinaria ornata, intraocular malignancy, silver nanoparticles, brown seaweed Turbinaria ornata, X‐ray diffraction, high‐resolution transmission electron microscopy, zeta potential, EDAX, thermogravimetric analysis, Fourier transform infrared spectrum, inductively coupled plasma‐mass spectroscopy, phenolic content, gallic acid, scavenging activity, in vitro retinoblastoma Y79 cell lines, dose‐dependent response, inhibitory concentration, anticancer agent, 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulphonic acid) assay, nanotechnology‐based cancer diagnosis, ocular tumour treatment, ultraviolet‐visible spectroscopy, Ag     

Factor-based evaluation for English to Hindi MT outputs

Design and implementation of automatic evaluation methods is an integral part of any scientific research in accelerating the development cycle of the output. This is no less true for automatic machine translation (MT) systems. However, no such global and systematic scheme exists for evaluation of performance of an MT system. The existing evaluation metrics, such as BLEU, METEOR, TER, although used extensively in literature have faced a lot of criticism from users. Moreover, performance of these metrics often varies with the pair of languages under consideration. The above observation is no less pertinent with respect to translations involving languages of the Indian subcontinent. This study aims at developing an evaluation metric for English to Hindi MT outputs. As a part of this process, a set of probable errors have been identified manually as well as automatically. Linear regression has been used for computing weight/penalty for each error, while taking human evaluations into consideration. A sentence score is computed as the weighted sum of the errors. A set of 126 models has been built using different single classifiers and ensemble of classifiers in order to find the most suitable model for allocating appropriate weight/penalty for each error. The outputs of the models have been compared with the state-of-the-art evaluation metrics. The models developed for manually identified errors correlate well with manual evaluation scores, whereas the models for the automatically identified errors have low correlation with the manual scores. This indicates the need for further improvement and development of sophisticated linguistic tools for automatic identification and extraction of errors. Although many automatic machine translation tools are being developed for many different language pairs, there is no such generalized scheme that would lead to designing meaningful metrics for their evaluation. The proposed scheme should help in developing such metrics for different language pairs in the coming days.