Vapor Species Over Te Precious Metal Minerals

This paper reports on two developments of interest to extractive metallurgists: how the knowledge of the vapors over tellurium minerals can be used to develop better processing methods and how graphite furnace atomic absorption, used at moderate temperatures, can be used to characterize the vapors over ore minerals. Elemental tellurium, Ag₂Te, and AuTe₂ were studied from 250°C through 1050°C. The vapors over these solids were analyzed in-situ by placing the solids directly into the graphite furnace of an atomic absorption spectrophotometer and adjusting the temperature accordingly. Atomic Ag, Au, and Te and molecular Te were analyzed in the vapor above the solids. Using absorbance versus temperature data, Clausius-Clapeyron plots were made to determine how the solids were changing.     

CuInGaSe2 crystals synthesis by selenization of Cu–In–Ga alloy in H2Se atmosphere for solar cell applications

Copper indium gallium diselenide (CuInGaSe₂) crystals were synthesized using two step growth strategy. A facile solution route was employed as a primary step to synthesize Cu–In–Ga (CIG) metallic precursor using ethylenediamine as a solvent. Thin films of CIG metallic precursor have been deposited using spray deposition technique on to molybdenum coated soda lime glass substrate under inert atmosphere. The subsequent step involved the selenization of metallic precursor thin films in H₂Se atmosphere at 450 °C for 90 min followed by annealing in Ar thus yielding solar cell applicable dense CuInGaSe₂ crystals. The surface morphology, phase structure and composition of the deposited films were analyzed by field emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and electrical resistivity measurement respectively. The results revealed that annealed films were crystalline in nature exhibiting homogeneous single chalcopyrite phase.     

Structure and magnetic properties of (Co,Mn) co-doped ZnO diluted magnetic semiconductor nanoparticles

The ZnO, Zn_0.96Mn_0.04O, Zn_0.95Mn_0.04Co_0.01O, Zn_0.94Mn_0.04Co_0.02O and Zn_0.92Mn_0.04Co_0.04O nanoparticles were synthesized by simple chemical precipitation technique. The effects of co-doping on the structure and magnetic properties of these nanoparticles were studied. The X-rays diffraction (XRD) scans were performed in the 2θ range of 20°–80°. The XRD patterns, at 300 K, of all the pure and co-doped ZnO samples confirmed the formation of wurtzite-type structure. X-ray diffraction and transmission scanning electron microscope analysis indicated that the high spin Co²⁺ and Mn²⁺ ions were substituted for the Zn²⁺ ions at tetrahedral sites. The average size of the nanoparticles were increased from 17 to 24 nm with the increase of dopants concentration. Moreover, Energy Dispersive X-ray spectroscopy (EDX) confirmed the synthesis results. All Zn_0.96?xMn_0.04Co _x O (x?=?0.0, 0.1, 0.2 and 0.4) nanoparticles samples were observed to be paramagnetic below 300 K. However, a large increase in the magnetization was observed below 40 K. This behavior, along with the negative value of the Curie–Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicated the ferromagnetic nature of the samples. The origin of ferromagnetism is likely to be the intrinsic characteristics of the Co and Mn doped samples. The high magnetization was noted for the 1 wt% Co co-doped Mn–ZnO annealed samples as compared to other samples with Co concentration above and below this threshold concentration.     

Reference-frequency generation by Raman-enhanced four-photon mixing

Reference-frequency generation for optical fiber instrumentation is now restricted to the frequency bands in which the reference materials have well-resolved absorption lines. We study analytically and experimentally the possibility of generating reference wavelengths by use of Raman-enhanced four-photon mixing in an optical fiber. We show that it is possible to generate efficiently frequencies that are 10-40 nm away from the absorption bands of the usual reference materials: acetylene (12C2H2), hydrogen cyanide (HCN), and similar or derived species. As a demonstration we use an acetylene cell to generate reference frequencies that cover the whole C (1530-1565 nm) and some part of the L (1565-1625 nm) transmission bands of the optical fiber.     

Encoder-Decoder Based LSTM Model to Advance User <i>QoE</i> in 360-Degree Video

The development of multimedia content has resulted in a massive increase in network traffic for video streaming. It demands such types of solutions that can be addressed to obtain the user's Quality-of-Experience (QoE). 360-degree videos have already taken up the user's behavior by storm. However, the users only focus on the part of 360-degree videos, known as a viewport. Despite the immense hype, 360-degree videos convey a loathsome side effect about viewport prediction, making viewers feel uncomfortable because user viewport needs to be pre-fetched in advance. Ideally, we can minimize the bandwidth consumption if we know what the user motion in advance. Looking into the problem definition, we propose an Encoder-Decoder based Long-Short Term Memory (LSTM) model to more accurately capture the non-linear relationship between past and future viewport positions. This model takes the transforming data instead of taking the direct input to predict the future user movement. Then, this prediction model is combined with a rate adaptation approach that assigns the bitrates to various tiles for 360-degree video frames under a given network capacity. Hence, our proposed work aims to facilitate improved system performance when QoE parameters are jointly optimized. Some experiments were carried out and compared with existing work to prove the performance of the proposed model. Last but not least, the experiments implementation of our proposed work provides high user's QoE than its competitors.     

Characterization of multifunctional nanosystems based on the avidin-nucleic acid interaction as signal enhancers in immuno-detection

The Avidin-Nucleic-Acids-Nano-Assembly (ANANAS) is a kind of soft poly avidin nanoparticle originating from the high affinity interaction between avidin and the nucleic acids. In this work we investigated the possibility of transforming ANANAS cores into stoichiometrically controlled multifunctional nanoparticles through a "one-pot" procedure, and we measured in a quantitative way their ability to work as reagents for enhanced immunodiagnostic detection. Initially, we measured the ANANAS loading capability for biotinylated proteins of different nature. About 200 molecules of biotin-horseradish-peroxidase (40KDa b-HRP) and 60 molecules of biotin-immunoglobulin-G (150KDa b-IgG) could be accommodated onto each nanoparticle, showing that steric limitations dictate the number of loadable entities. Stoichiometrically controlled functional assemblies were generated by mixing core particles with subsaturating amounts of b-HRP and b-IgG. When applied as detection reagents in an Enzyme-Linked-ImmunoSorbed-Assay (ELISA), these assemblies were up to two-orders of magnitude more sensitive than commercial HRP-based reagents. Assemblies of different composition displayed different efficacy, indicating that the system functionality can be fine-tuned. Within-assay variability (CV%), measured to assess if the assembly procedure is reproducible, was within 10%. Stability experiments demonstrated that the functionalyzed assemblies are stable in solution for more than one week. In principle, any biotinylated function can be loaded onto the core particle, whose high loading capacity and tunability may open the way toward further application in biomedicine.     

Institutional h-index: The performance of a new metric in the evaluation of Brazilian Psychiatric Post-graduation Programs

A fair assessment of merit is needed for better resource allocation in the scientific community. We analyzed the performance of the institutional h-index in the case of Brazilian Psychiatry Post-graduation Programs. Traditional bibliometric indicators and the institutional h-index similarly ranked the programs, except for the Average Impact Factor. The institutional h-index correlated strongly with the majority of the traditional bibliometric indicators, which did not occur with the Average Impact Factor. The institutional h-index balances “quantity” and “quality”, and can be used as part of a panel of bibliometric indicators to aid the peer-review process.     

Effects of Packaging and Preservation Treatments on the Shelf Life of Murtilla Fruit (Ugni molinae Turcz) in Cold Storage

Murtilla (Ugni molinae Turcz) fruit has a unique aroma; along with its pleasant sweet flavour, this has stimulated its commercial development in international markets. This development, however, requires the application of suitable conservation methods. Five different packaging treatments for murtilla fruit (Red Pearl‐INIA variety) conservation were evaluated at 0 °C for 60 days. The treatments consisted of two types of packaging [polyethylene terephthalate (PET) punnets and low‐density polyethylene (LDPE) bags] and the application of an edible coating of carboxymethyl cellulose to the fruits. The incorporation of the aqueous extracts of murtilla leaves from the 18‐1 and 27‐1 ecotypes into the carboxymethyl cellulose edible coating was also evaluated for its antimicrobial effects. There was a significant (p < 0.05) reduction in the moisture content, a significant weight loss and an increase in soluble solids when the murtilla fruit was packed only in a PET punnet. However, with the other four treatments, in which an LDPE bag and edible coating were used, the moisture content (76.8–74.4 g/100 g) and soluble solids (15.6–17.8 ºBrix) in the fruit remained stable during storage. Low weight loss (1.64–2.25%) occurred in the fruits that received treatments with the LDPE bag and edible coating. Under experimental conditions and from operational facilities, packaging in PET punnets with an LDPE bag was the best alternative to preserve the murtilla fruit at 0 °C for 60 days. Copyright © 2013 John Wiley & Sons, Ltd.     

Transparent Alumina/Ceria Nanocomposites By Spark Plasma Sintering

The influence of oxides (such as MgO, TiO₂, CaO, etc.) on the transparency of polycrystalline alumina compacts are widely studied in the literature. In this work, a completely different approach is developed, consisting of precipitating 0.5 wt.‐% CeO₂ nanoparticles (< 5 nm) on the surface of the starting alumina nanopowder (d₅₀ approximately 170 nm) using cerium(III) acetate as precursor. It is shown that the ceria nanoparticles strongly enhance the transparency of the spark plasma sintered compacts due to: i) the ceria nanoparticles acting as powder lubricant, increasing by around 15% the initial density of the powder in the SPS die, and, ii) the CeO₂ nanoparticles, having a very low solid solubility in the alumina grains, locating at grain boundaries, hindering alumina grain growth by pinning during SPS sintering at 1 430 °C, 80 MPa for 2 min. This effect is found to be effective only under SPS vacuum conditions. In order to explain the light scattering behavior in the near‐infrared and visible range, a light scattering model under the Rayleigh‐Gans‐Debye approximation for polycrystalline alumina is used. This model offers an additional and simple tool for a completed bulk evaluation of the SPS compacts microstructure.     

Surface-enhanced Raman spectroscopy studies of orderly arranged silica nanospheres-synthesis,characterization and dye detection

Silica nanospheres have been explored much for drug delivery, photocatalysis, sensors and energy storage applications. It also acts as a template for Surface-Enhanced Raman Spectroscopy (SERS) substrates. Uniform nanostructures at low cost with high reproducibility are the major challenges in SERS substrate fabrication. In the present work, silica nanospheres were synthesized using stober method and deposited on to glass slides using Vertical deposition techniques. Different size/thickness of Silver (Ag) nanoparticles were deposited onto silica thin films using sputter deposition technique. The monodispersity of silica nanospheres and size of silver nanoparticles (10 nm, 20 nm and 30 nm) were confirmed by FESEM analysis. The structural properties were confirmed through XRD. UV–Vis analysis revealed that the plasmonic properties of Ag@SiO₂ give high surface plasmons for 30 nm thickness of silver. The binding energy of Ag@SiO₂ confirmed through XPS spectrum. The fabricated SERS substrates were used to detect Rhodamine 6G (R6G), Methylene blue (MB), Methylene violet (MV) and Methyl orange dyes as an analyte molecule with a limit of detection at about 10^?11 mol/L. The addition of SiO₂ nanospheres decreases the Ag oxidation rate and increases their stability. The maximum enhancement factor (1.5?×?10⁷) achieved for 30nm thickness of Ag@SiO₂. The results and technique establish the potential applications and reproducible SERS substrate.