Upconversion fluorescent material such as NaYF.sub.4:Yb/Re (Re is lanthanide ions) nanoparticles has considerable application prospect, but the fluorescence efficiency is usually too low. In this ...paper, an effective approach has been validated to enhance the fluorescence intensity of NaYF.sub.4:Yb/Re by coupling with SiO.sub.2 opal photonic crystals (PCs). NaYF.sub.4:Yb/Tm and NaYF.sub.4:Yb/Er were prepared by thermal decomposition method and ligand exchange, and then spin-coated on the surface of SiO.sub.2 opal PCs with different photonic band gap (PBG). The PBG properties of PCs/UCNPs composite films were measured by transmission spectra. The effect of overlapping extent between PBG and UCNPs' emission on upconversion emission enhancement was studied through fluorescence spectra. The result shows that when the SiO.sub.2 opal PCs with the PBG at 448 nm were composited with NaYF.sub.4:Yb/Tm, the upconversion fluorescence at 450 nm was enhanced mostly, which is 34-fold. Similarly, the highest enhancement, 23-fold, was observed for fluorescence of NaYF.sub.4:Yb/Er at 541 nm when composited with SiO.sub.2 opal PCs having PBG at 544 nm. According to the analysis, the upconversion fluorescence can be enhanced through coupling with PCs by utilizing the light reflection and light localization effect of PCs. At the same time, the highest enhancement is obtained when the PBG of PCs is exactly overlapping with the wavelength of upconversion fluorescence. Our study potentially will contribute to promoting the sooner practical application of upconversion nanoparticles.
This paper reports enhanced high-temperature piezoelectric properties of Bi(Zn.sub.0.5Ti.sub.0.5)O.sub.3-modified BiFeO.sub.3-BaTiO.sub.3 (BF-BT-xBZT) ceramics prepared by two-step sintering method. ...The resultant ceramics show a symmetrical transition from a rhombohedral-pseudo-cubic (R-PC) phase coexistence to main PC phase with the increase of x, whose R-PC fraction (C.sub.R/C.sub.PC) is 53.3/46.7, 52.9/47.1, 50.2/49.8, 27.4/72.6, 15.3/84.7 when x = 0, 0.005, 0.01, 0.03, 0.05, respectively. The modification of BZT inhibits the grain growth, reduces the leakage current and gradually drives ferroelectric to relaxor transition. Optimal piezoelectric properties: d.sub.33 = 193 pC N.sup.-1, P.sub.r = 20.6 muC cm.sup.-2, T.sub.C = 503 °C and k.sub.p = 36% achieved at x = 0.01 composition, which is due to the synergistic effect of an appropriate C.sub.R/C.sub.PC ratio, improved insulation and good polarization performance. In addition, the depolarization temperature T.sub.d is close 280-312 °C, and the high-temperature d.sub.33 further increases to 286-347 pC N.sup.-1, which shows a good application prospect of lead-free piezoceramics at high temperature. Our work also confirms that the addition of (Zn.sub.0.5Ti.sub.0.5).sup.3+ and two-step sintering method are an effective and convenient strategy to improve the high-temperature electrical performance of BiFeO.sub.3-BaTiO.sub.3 based lead-free ceramics.
The phase diagram of dense quark matter with chiral imbalance is considered with the conditions of electric neutrality and Formula omitted-equilibrium. It has been shown recently that chiral ...imbalance can generate charged pion condensation (PC) in dense quark matter. It was, therefore, interesting to verify that this phenomenon takes place in realistic physical scenarios such as electrically neutral quark matter in Formula omitted-equilibrium, because a window of charged PC at dense quark matter phase diagram (without chiral imbalance) predicted earlier was closed by the consideration of these conditions at the physical current quark mass. In this paper it has been shown that the charged PC phenomenon is generated by chiral imbalance in the dense electric neutral quark/baryonic matter in Formula omitted-equilibrium, i.e. matter in neutron stars. It has also been demonstrated that charged PC is an inevitable phenomenon in dense quark matter with chiral imbalance if there is nonzero chiral imbalance in two forms, chiral and chiral isospin one. It seems that in this case charged PC phase can be hardly avoided by any physical constraint on isospin imbalance and that this conclusion can be probably generalized from neutron star matter to the matter produced in heavy ion collisions or in neutron star mergers. The chiral limit and the physical point (physical pion mass) have both been considered and it was shown that the appearance of charged PC is not much affected by the consideration of nonzero current quark mass.
Introducción. La calidad nutritiva de las especies vegetales que se usan en sistemas silvopastoriles es importante para tener un óptimo desempeño productivo del ganado. Objetivo. Conocer la calidad ...nutricional de especies vegetales que se aprovechan en la ganadería bovina de doble propósito de Loma Bonita, Oaxaca, México. Métodos. Se identificaron especies vegetales que se usan como cercos vivos en potreros y pastos para la producción de ganado en Loma Bonita y se consultó en la literatura su aporte en porcentaje de materia seca (MS%), proteína (PC%), extracto etéreo (EE%), cenizas (CE%), fibra detergente ácido (FDA%) y neutro (FDN%). Resultados y discusión. Los contenidos nutrimentales de las especies arbóreas (cuadro 1) y de algunos pastos tropicales (cuadro 2) varían según el sitio de producción, clima y edad de rebrote. Conclusión. Existen especies arbóreas y pastos con gran potencial de uso en sistemas silvopastoriles de trópico húmedo.
Polymer composites and blend systems are of increasing importance, due to the combination of unique and different material properties. Blending polybutylene terephthalate (PBT) with polycarbonate ...(PC) has been the focus of attention for some time in order to combine thermo-chemical with mechanical resistance. The right compounding of the two polymers is a particular challenge, since phase boundaries between PBT and PC lead to coalescence during melting, and thus to unwanted segregation within the composite material. Amorphization of the semi-crystalline PBT would significantly improve the blending of the two polymers, which is why specific miscibility aids are needed for this purpose. Recent research has focused on the functionalization of polymers with shape-anisotropic glass particles. The advantage of those results from their two-dimensional shape, which not only improves the mechanical properties but are also suspected to act as miscibility aids, as they could catalyze transesterification or act as crystallization modifier. This work presents a process route for the production of PBT-PC blends via co-comminution and an in-situ additivation of the polymer blend particles with anisotropic glass flakes to adjust the crystallinity and therefore enhance the miscibility of the polymers.
In einer Zeit, in der digitale Technologien nahezu jeden Aspekt unseres Lebens durchdringen, ist es unerlässlich, die tieferen Zusammenhänge des digitalen Konsums zu verstehen. Erstmalig bietet ...dieses open access-Lehrbuch einen Wegweiser durch die vielfältigen Facetten der Digitalisierung des Konsums. Dabei verbindet es die Disziplinen der angewandten Informatik und Verbraucherwissenschaften. Die Leserinnen und Leser erhalten Einblick in die digitale Konsumlandschaft, ausgehend von der historischen Entwicklung des (digitalen) Konsums. Dazu vermittelt das Lehrbuch zentrale Grundbegriffe und Themen der Verbraucherinformatik und stellt verschiedene Konsumtheorien aus den Disziplinen Wirtschaftswissenschaften, Psychologie und Sozialwissenschaften vor. Praxisnahe Beispiele aus der Digitalisierung bieten Einsichten in unterschiedliche Perspektiven, während vertiefende Textboxen und Selbstreflexionsfragen das Verständnis fördern. Inhaltlich decken die Autorinnen und Autoren Themen von Datenschutz bis zur Sharing Economy ab und geben insbesondere auch praktische Ansätze für Themen wie Verbraucherschutz und Nachhaltigkeit mit auf den Weg. Die Anwendungs- und Querschnittsthemen der Verbraucherinformatik reichen von der Digitalisierung der Haushalte und Märkte über Fragen des digitalen Verbraucherschutzes bis hin zu zentralen gesellschaftlichen Fragestellungen rund um die Themen Fairness, Verantwortung und Nachhaltigkeit bei der Gestaltung von digitalen Technologien. Das Buch bietet einen umfassenden Überblick, der sowohl für Studierende der Wirtschafts- und Sozialwissenschaften als auch der angewandten Informatik von bedeutendem Wert ist.
A metallo-organic cobalt phthalocyanine (denoted as Co-Ph), which has a cobalt core and a N-containing conjugated organic shell, has recently been discovered as a source of C, N, and Co, applying as ...a single precursor for fabricating Co.sub.3O.sub.4/nitrogen-doped porous carbon (denoted as Co.sub.3O.sub.4/N-PC) by one-step pyrolysis. Cobalt phthalocyanine has a N-containing conjugated organic shell and benefiting from the restriction of the organic ligands, Co atoms form 20 nm Co.sub.3O.sub.4 particles and well distribute in N-doped carbon during pyrolysis. The obtained product has well-embedded Co.sub.3O.sub.4 particles, and the porous N-doped carbon provides abundant channels for Li-ion transport and serves as a conductive network, increasing charge/discharge efficiency and reducing electrode resistance. Owing to these advantages, the composite shows good electrochemical performances when applied as an anode in a Li-ion battery. For instance, it has high initial discharge and charge capacities of 1336.7 and 849.8 mAh g.sup.-1, respectively, at 200 mA g.sup.-1, and it retains a reversible capacity of 577.0 mAh g.sup.-1 after 236 cycles at a range of current densities. Moreover, this method greatly reduces the cost of production and may be extended to produce a range of metal oxide/N-PC materials, for instance ZnO/N-PC.
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