Improved quantum efficiency of Sr(Al,Si)5(O,N)7:Ce3+ by selection of Ce raw material

The luminescence properties of yellow-emitting Ce³⁺-doped Sr-containing sialon phosphor Sr(Al,Si)₅(O,N)₇:Ce³⁺ were notably improved by the Ce raw material selection. By changing the Ce raw material from oxides to nitrides or chlorides, the emission wavelength shifted to above 560 nm, which is beneficial for higher color rendering index white light-emitting diodes. This result from an increase in the covalency of the host crystal being associated with a decrease in the oxygen content. When Ce chloride was used, both the absorption and internal quantum efficiency increased, resulting in an increase in the external quantum efficiency up to 65%–72%. Inductively coupled plasma mass spectrometry, X-ray diffraction, and electron spin resonance measurements showed that the reason for the absorption increase is an increase in Ce³⁺ content and suppression of the generation of the second phase, and the reason for the increase in the internal quantum efficiency is a decrease in the host crystal absorption via suppression of anion vacancy generation. It was found that Ce chloride not only suppresses oxygen impurities but also acts as a flux that results in improved crystallinity.     

Mechanical properties of polyethylene mixtures crystallized under high pressure

The mechanical properties of a medium molecular weight polyethylene (MMW‐PE) and an ultrahigh molecular weight PE (UHMW‐PE) binary mixture with different weight fractions crystallized from the melt at 0.1 and 450 MPa were studied. The tensile modulus, yield stress, and strain were obtained as a function of the weight fractions in the PE mixtures at 25 and 85°C. The tensile modulus in the sample crystallized at 0.1 MPa decreased from 1.5 GPa of pure MMW‐PE to about 0.4 GPa of pure UHMW‐PE with the UHMW‐PE content but it did not decrease with the UHMW‐PE in the sample crystallized at 450 MPa in testing at 25°C. A decreasing rate of the storage modulus E′ of UHMW‐PE in a dynamic measurement for the sample crystallized at 0.1 MPa with the temperature is larger than that of the sample crystallized at 450 MPa. These experimental facts are interpreted in relation to the molecular motion and crystallinity of the sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1962–1968, 2003     

a-Si alloy three-stacked solar cells with high stabilized-efficiency

a-Si alloy three-stacked solar cells have been studied to improve the stabilized efficiency of a-Si: H based solar cells. Based on the analysis by the individual characterization method of the component cells in stacked type cells, the a-Si :H middle cell was replaced with an a-SiGe :H cell. Furthermore, the optical confinement technology was improved to obtain a high-output current with thin i-layer thickness in the a-SiGe :H bottom cell. By this device design, the initial conversion efficiency was improved up to 12.4% and more than a 10% stabilized efficiency was obtained in a-SiC :H/a-SiGe :H/a-SiGe :H three-stacked cells. These cell characteristics were confirmed by measurements at the JQA Organization (the former JMI Institute).     

Feasibility of fishmeal replacement by shrimp head silage protein hydrolysate in Nile tilapia (Oreochromis niloticus L) diets

This study provides information on the use of shrimp head silage protein hydrolysate (SPH) as an alternative protein source for tilapia feeding. Six diets (28% protein, 12% lipid) were prepared where fishmeal protein was replaced at levels of 0 (control), 10, 15, 20, 25 and 30% with the hydrolysate. The diets were supplied to Nile tilapia fry (338 mg initial weight) stocked in plastic recirculating 20 l tanks (10 animals per tank), with three replicates per treatment. After an 8 week experimental period, fish fed the diets containing 10 and 15% SPH showed significantly better performance in terms of final body weight, weight gain (%), mean daily weight gain (mg day^?1), specific growth ratio and feed conversion ratio than those fed the control diet (fishmeal as protein source) and higher‐SPH diets. It is concluded that shrimp head hydrolysate is a promising alternative protein source for tilapia feeding, improving growth ratio at dietary inclusion levels as high as 15%. In addition, the diets with added shrimp silage protein were well accepted by the fish, which avidly consumed the feed during the experiment. © 2002 Society of Chemical Industry     

One-Step Synthesis of Luminescent Nanoparticles of Complex Oxide, Strontium Aluminate

An organic aqueous solution of metal acetylacetonate precursors was subjected to spray pyrolysis in order to fabricate SrAl₂O₄:Eu (SAO) nanoparticles. Non-agglomerated luminescent SAO nanoparticles, having a spherical shape with a size of 10–30 nm, were achieved in a single step, while only submicrometer-sized SAO particles were obtained from the conventional ultrasonic pyrolysis of the metal nitrates. Without any post-annealing process, the as-prepared SAO nanoparticles were observed to exhibit a strong photoluminescence, which is comparable with that of the submicrometer-sized SAO particles. A mechanism for the formation of the nanoparticles is also discussed.     

Chemical response of Picea glehnii seed-epiphytic Penicillium species to Pythium vexans under in vitro competitive conditions for mycelial growth

The potential protection of Picea glehnii seedlings from damping-off by seed-epiphytic Penicillium species was investigated. We studied the chemical response of seed-epiphytic Penicillium species (Pen. cyaneum, Pen. damascenum, and Pen. implicatum) to Pythium vexans, a damping-off fungus, in vitro. Penicillium species were cultured singly or cocultured with Pyt. vexans for 14 or 18 d, and mycelial growth, pH of culture filtrate, antifungal activity of the culture filtrate against Pyt. vexans, and the amount of antifungal compound produced by each Penicillium species, were examined. The filtrate of both the single culture of Penicillium and the coculture of Penicillium and Pyt. vexans showed antifungal activity against Pyt. vexans. In a coculture with Pyt. vexans, Pen. cyaneum produced an antifungal compound (patulin) as in the single culture. Pen. damascenum cocultured with Pyt. vexans produced an antifungal compound (citrinin), as it did in the single culture and in larger amounts on day 10. Pen. implicatum produced two antifungal compounds, frequentin and palitantin, and the ratio of frequentin (with higher antifungal activity than palitantin) to palitantin was higher in the coculture with Pyt. vexans than in the single culture. Our results indicate that these Penicillium species have the ability to produce antifungal compounds and to keep antifungal activity under competitive condition with Pyt. vexans. The chemical response of these Penicillium species to Pyt. vexans may contribute to protect P. glehnii seedlings from damage by Pyt. vexans.     

Properties of novel diallyl phthalate resin modified with sulfur‐containing allyl ester compounds

Sulfur‐containing allyl ester, which reacts with diallyl phthalate (DAP) resin to have allyl groups, was synthesized by the reaction of allyl phthalic acid with bisphenol having sulfur atoms. The sulfur‐containing allyl ester compound was blended with DAP resin to improve the adhesive properties to copper. By modification with sulfur‐containing allyl ester compound, the T‐peel adhesive strength and the lap shear adhesive strength to copper was improved. In particular, the adhesive strength was greatly improved when the resin was modified with the allyl ester compound having a disulfide bond (?S?S?) (DADS). It is concluded that this result is due to the improvement of the interfacial adhesive strength because the sulfur atom was found to be located in the surface of the copper by Fourier transform infrared (FTIR) analysis. The glass transition temperature (T_g) and the thermal decomposition temperature (T_d) of the cured DAP resin modified with DADS slightly decreased with increasing concentration of DADS. The lowering of T_g is because the crosslinking density of the DAP resin modified with DADS is smaller than that of DAP resin. Moreover, from thermogravimetric analysis, the lowering of Td of the DAP resin modified with DADS is because DADS is likely to pyrolyze. © 2013 Society of Chemical Industry     

Possible Reaction Mechanism for the Formation of C60 From Naphthalene: A Semi-Empirical and Ab Initio Molecular Orbital Study

Abstract

Mechanism of C₆₀ formation from naphthalenes was studied by quantum chemical calculations. a patch up process of T-shape dimerization of naphthalenes followed by the intramolecular ring fusion, all through radical reactions, was proposed for a possible mechanism for the C₆₀ formation from naphthalenes. the reaction barrier was found to be less than 60-70 kcal/mol for each reaction step in this mechanism.