Effect of air annealing on the optical properties and luminescence performance of Ce:YAG ceramics for light-emitting diodes at different Ce concentrations

(Y_1-x%Ce_x%)₃Al₅O₁₂ (x = 0.2,0.4,0.6,0.8,1.0) transparent ceramics were fabricated by vacuum sintering technology, followed by air annealing at different temperatures. Transmittance of ceramics, valence of cerium, and luminescent properties with varying annealing temperatures are studied in detail. The negative effect of Ce³⁺ oxidation induced by annealing gets increasingly evident when Ce concentration increases. Collaborating Ce:YAG ceramics with InGaN blue chips, light-emitting diodes (LEDs) with superior performance were constructed. The relationships between Ce concentration, annealing temperature, and luminous flux of LEDs are elucidated, showing that the optimized annealing temperature of Ce:YAG ceramics decreases from 1200 °C to 900 °C as Ce concentration increases from 0.2 at% to 1.0 at%. The luminous fluxes of optimized LEDs increase by ～10 % compared with that of unannealed LEDs.     

A state-of-the-art review on the elaboration of fish gelatin as bioactive packaging: Special emphasis on nanotechnology-based approaches

BackgroundThe last decade has noticed the expansion of green materials, which aims to reduce the human impact on the environment. Green polymers are clearly tendency subdivision of this stream and numerous bio-sourced plastics have been developed. Recent research has further focused on the development of new bio-based materials such as edible/biodegradable films for food products.Scope and approachFish gelatin (FG), a protein with recreatable reserve, biodegradability, and processability, has a remarkable potential in bio-packaging. However, there have been noticeable issues concerning the use of FG as packing material, including its low mechanical strength, poor moisture stability, and poor water barrier properties. This paper aims to review the state-of-the-art in development of FG-based films and highlights how they play a crucial role in modifying the properties of such films. Various types of nanofillers that have been included into FG to fabricate bio-nanocomposite films, such as nanoclays (montmorillonite, sepiolite), polysaccharide nanofillers (nanowhiskers/nanofibers), metal ions (silver, copper) and metal oxides nanoparticles (ZnO, TiO₂) are reviewed.Key findings and conclusionsCross-linking is a promising technique to improve the performance and applicability of FG-based biomaterials, particularly respecting their water sensitivity, which hinders many of their potential uses as food contact materials. Bio-nanocomposite technology may help to make high-performance materials with extra bio-functional properties, and it is anticipated to be a dynamic research in the future. In general, more research is required to ameliorate application processes of FG films, especially physical aspects, to be suitable for bio-packaging application.     

First demonstration of photoelectrochemical water splitting by commercial W–Cu powder metallurgy parts converted to highly porous 3D WO3/W skeletons

Hydrogen evolution through photoelectrochemical (PEC) water splitting by tungsten oxide-based photoanodes, as a stable and environmental-friendly material with moderate band gap, has attracted significant interest in recent years. The performance of WO₃ photoanode could be hindered by its poor oxygen evolution reaction kinetics and high charge carrier recombination rate. Additionally, scalable and cost-effective commercial procedure to prepare nanostructured electrodes is still challenging. We present, for the first time, a novel and scalable method to fabricate highly efficient self-supported WO₃/W nanostructured photoanodes from commercial W–Cu powder metallurgy (P/M) parts for water splitting. The electrodes were prepared by electrochemical etching of Cu networks followed by hydrothermal growth of WO₃ nanoflakes. Interconnected channels of W skeleton provided high active surface area for the growth of WO₃ nanoflakes with a thickness of ~40 nm and lateral dimension of ~250 nm. The optimized photoelectrode having 35% interconnected porosity exhibited an impressive current density of 4.36 mA cm⁻² comprising a remarkable photocurrent of 1.71 mA cm⁻² at 1.23 V vs. RHE under 100 mW cm⁻² simulated sunlight. This achievement is amongst the highest reported photocurrents for WO₃ photoelectrodes with tungsten substrate reported so far. Impedance and Mott-Schottky analyses evidenced fast charge transfer, low recombination rate, and accelerated O₂ detachment provided by optimum 3D porous WO₃/W electrode. Due to the nature of the commercial P/M parts and low-temperature hydrothermal processing, the procedure is cost-effective and scalable which can pave a new route for the fabrication of highly porous and efficient water splitting electrodes.     

Flotation performance and adsorption mechanism of novel 1-(2-hydroxyphenyl)hex-2-en-1-one oxime flotation collector to malachite

A novel collector 1-(2-hydroxyphenyl)hex-2-en-1-one oxime (HPHO) was synthesized from 2-hydroxy acetophenone and butyraldehyde. Its flotation performance and adsorption mechanism to malachite were investigated by flotation test, zeta potential, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis techniques. Compared with benzohydroxamic acid (BA), 1-(2-hydroxyphenyl)ethan-1-one oxime (HPEO) and sodium isobutyl xanthate (SIBX), HPHO exhibited excellent collecting power to malachite without additional reagents, such as Na₂S regulator and methyl isobutyl carbinol (MIBC) frother. Results of zeta potential indicated that HPHO was coated on malachite surfaces through a chemisorption process. FTIR and XPS data gave clear evidence for the formation of Cu–oxime complex on malachite surfaces after HPHO adsorption through the linkage between C=C, –OH, N–OH group and Cu species.     

The effects of the energy price reform on households consumption in Iran

The substantial subsidizing of energy prices over the years has led to high energy consumption, inefficiencies, fiscal pressures, and environmental problems in Iran. To address the increasing socio-economic problems associated with the energy subsidies, the government embarked on an aggressive energy price reform through which energy subsidies were removed and cash handouts were given to all households in 2010. In this paper, I analyze the effectiveness of the energy price reform in Iran by estimating energy demand elasticities for households in different income groups. I apply a two-stage consumer optimization model and estimate the system of energy expenditures shares using the household budget survey data for the period 2001–2008. The results show that the overall price elasticities of demand are small, but income elasticities are close to one. The results also indicate heterogeneous responses to energy price and income changes in different income groups. Specifically, the urban households show stronger response to price changes, but rural households, particularly mid-income households, to income changes. These findings suggest that the current policy of price increases would not solely be able to reduce energy consumption and, therefore, it should be geared towards increasing energy efficiency through a series of price and non-price measures.     

Efficient framework for mobile walkthrough application

The past few years have witnessed a dramatic growth in the number and variety of graphics intensive mobile applications, which allow users to interact and navigate through large scenes such as historical sites, museums and virtual cities. These applications support many clients and impose a heavy requirement on network resources and computational resources. One key issue in the design of cost efficient mobile walkthrough applications is the data transmission between servers and mobile client devices. In this paper, we propose an effective progressive mesh transmission framework that stores and divide scene objects into different resolutions. In this approach, each mobile device progressively receives and processes only the object’s details matching its display resolution which improves the overall system’s response time and the user’s perception. A fine grained cache mechanism is used to keep the most frequently requested objects’ details in the device memory and consequently reduce the network traffic. Experiments, in simulated and real world environment, are used to illustrate the effectiveness of the proposed framework under various settings of the virtual scene and mobile device configuration. Experimental results show that the proposed framework can improve the walkthrough system performance in mobile devices, with a relatively small overhead.     

Market power issues in the reformed Russian electricity supply industry

The paper examines long-run and short-run levels of market power in the liberalised Russian electricity market. We observe that despite potential for market power abuse, actual exercise of market power remained low. We attribute the result to the bid-at-cost rule implemented as a part of a special unit commitment procedure on the day-ahead market. We first look at the industry restructuring and subsequent mergers and acquisitions. The M&A were undertaken in different market zones and did not seem to increase concentration although planned zone integration may worsen competition in the long run. We then examine short-run aspect of market power by estimating hourly price–cost mark-ups and assessing their dynamics in 2010 and 2011, a year preceding and following the market liberalisation, respectively. The hypothesis of actual market power abuse is tested, and rejected, using time series AR models. Further, a Tobit regression shows that the liberalisation decreased the mark-ups by about 1.66 percentage points.     

Co-existing of dressed non-linear gain and electromagnetically induced absorption

The dressed parametric four-wave mixing (FWM) process has been investigated in hot atomic rubidium vapor. We use a strong pumping field to generate entangled photon pairs of spontaneous parametric FWM (SP-FWM) which can be enhanced by an external dressing effect. Seeding probe beam into the Stokes or anti-Stokes (SP-FWM) channel will form the parametric amplified FWM (PA-FWM) process, then the non-linear gain and electromagnetically induced absorption (EIA) are observed, caused by the internal dressing effect. However, with scanning of pumping field the absorbing background will vanish, which will result in drastic increase in PA-FWM signal gain.     

Tuning the interfacial reaction between CaO–SrO–Al2O3–B2O3–SiO2 sealing glass–ceramics and Cr-containing interconnect: Crystalline structure vs. glass structure

In this paper, Al₂O₃ was added to CaO–SrO–B₂O₃–SiO₂ sealing system to tailor the structure of sealing glass–ceramics and glass–ceramics/metal interfacial reaction. The addition of alumina in glasses contributes to increasing fraction of bridging oxygen in silica tetrahedral as well as the change in boron environment from three-fold to four-fold (BO₄ → BO₃). The devitrification tendency of glasses also decreases with increasing Al₂O₃ content. The condensed glass structure and increasing residual glass content play opposite roles on the interfacial reaction, consequently resulting in a maximum fraction of Cr⁶⁺ in reaction couples between Cr₂O₃ and glass containing 6 mole% Al₂O₃ at 700 °C. In addition, the good bonding can be observed at the interface between Cr-containing interconnect (Crofer 22APU) and glass containing 4 mole% Al₂O₃, held at 700 °C for 100 h. The reported results support the suitability of the prepared glass–ceramics as sealing materials for SOFC applications.     

球形木质素珠体接枝丙烯腈的影响因素研究

利用反相悬浮聚合技术制备球形木质素珠体,再以Fe2＋/H202为引发体系,采用正交实验综合研究了球形木质素珠体与丙烯腈的接枝共聚反应的各种影响因素对珠体的接枝率和接枝效率的影响。结果表明：当m（单体）／m（基体）=10：1,反应时间为90min,反应温度55℃,Fe2＋浓度为0．03mmol／L,H202浓度为2．97mmol／L时,可以得到最佳的接枝率和较高的接枝效率,木质素一丙烯腈接枝共聚物的接枝率为780％,接枝效率可达76．0％。