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Abstract: To date, the incidence and mortality of chronic liver diseases such as cirrhosis and hepatocellular carcinoma due to the continued progression of hepatic fibrosis are increasing annually. Unfortunately, although a large number of studies have exhibited that some drugs have great potential for anti-fibrosis in animal and clinical trials, no specific anti-fibrosis drugs have been developed, and there is no better treatment for advanced cirrhosis than liver transplantation. It is a prevailing viewpoint that hepatic stellate cells (HSCs), as the mainstay of extracellular matrix secretion, are of great concern in the development of hepatic fibrosis. Therefore, targeting HSCs becomes extremely important to confront hepatic fibrosis. As previous studies described, inhibition of HSC activation and proliferation, induction of HSC death, and restoration of HSC quiescence are effective in reversing hepatic fibrosis. This review focuses on the current status of research on the treatment of hepatic fibrosis by inducing HSC death and elucidates the HSC death modes in detail and the crosstalk between them.

Substantial lattice strain arising from lattice misfit of the components of core–shell nanomaterials used to accommodate lanthanide emitters usually significantly results in an inhomogeneous shell,...

In this work, Lu7O6F9 microcrystals with various novel morphologies, including hand broom-like nanorods, nanoparticles, hexagons, spindle-like nanoparticle aggregates, hexagonal prisms and microrods, were prepared via ionic liquid-assisted two-phase method and following calcination approach. Ionic liquid was used as F− resource, morphology controller and two-phase solvent. The effect of preparation condition on the phases and morphologies of the precursors as well as the calcined products was studied in detail. The crystallographic structure of Lu7O6F9 was also confirmed by the down-conversion (DC) spectra of Lu7O6F9: Eu3+ phosphor with Eu3+ ion as the structure probe. Besides, different concentration of Yb3+ ions were introduced to the host to obtain Lu7O6F9: Yb3+, Er3+ phosphors, in case of subsequent investigation on the up-conversion (UC) luminescence properties, UC mechanism and followed temperature sensing behavior. Color-tunable UC emissions were realized and the mechanism was discussed. Furthermore, the optical temperature sensing behavior of orthorhombic Vernier lutecium oxyfluoride was investigated for the first time. The influence of Yb3+ content on the sensing sensitivity was also elaborated. These results imply that the as-prepared Lu7O6F9: Yb3+, Er3+ phosphors could be considered as candidates in color-tunable displaying and optical thermometers.

Color-tunable phosphors can be obtained through codoping strategies and energy transfer regulation. Ce3+ and Eu2+ are the most common and effective activator ions used in phosphor materials. However, the energy transfer from Eu2+ to Ce3+ is rarely reported. In this work, Y2Mg2Al2Si2O12(YMAS):Eu2+,Ce3+ phosphors were successfully synthesized, which was confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Rietveld refinement, scanning electron microscopy (SEM) and element mapping images, and spectral information. The luminescent color of YMAS:Eu2+,Ce3+ phosphors could be tuned from blue to cyan to light green to yellow-green and finally to green-yellow, which was achieved by adjusting the energy transfer between different dopants. The energy transfer from Eu2+ to Ce3+ was confirmed by photoluminescence spectra and fluorescence decay curves. Within the experimental gradient, the energy transfer efficiency could reach up to 48%. At 373 K, the Y1.99Mg1.99Al2Si2O12:0.01Eu2+,0.01Ce3+ (YMAS:0.01Eu2+,0.01Ce3+) phosphor exhibited a total integral emission loss of only 8%, and the emission peak intensity decreased to 95%, indicating the excellent thermal stability. The white light-emitting diode (WLED) fabricated by the YMAS:0.01Eu2+,0.01Ce3+ phosphor has the same level correlated color temperature (CCT = 5841 K), greatly improved color rendering index (Ra = 87.8), and higher quality white light color (CIE = (0.3258, 0.3214)) than the WLED made by the YMAS:0.01Eu2+ phosphor, indicating that the performance of the phosphor was significantly improved by introducing Ce3+. This work provides an effective guide for the design and development of highly efficient color-tunable phosphors involving energy transfer from Eu2+ to Ce3+ in some specific materials, such as garnet structures.

Here, the crystal structure, phase analysis, site occupancy, and luminescence properties of NCMP:Eu2+,Tb3+,Mn2+ have been studied for the first time. Under 335 nm ultraviolet excitation, the NCMP:E...

Structure determines properties, and properties determine applications, which is an important ideology of natural sciences. For optical materials, it is vital to lucubrate the corresponding relationship between the local crystal structure and luminescence properties for their design, synthesis, and application. This work reports a newly designed Y2Mg2Al2Si2O12(YMAS):Eu3+ red phosphor, in which difunctional Eu3+ ion is used as a red-light activator and spectroscopic probe. The qualitative and quantitative studies on the relationship between the local crystal structure and the luminescence properties of YMAS:Eu3+ are performed experimentally and computationally, using the Y3Al5O12 (YAG):Eu3+ as contrast. Moreover, compared with YAG:Eu3+, the newly designed YMAS:Eu3+ has stronger luminescence, superior Commission Internationale de L'Eclairage chromaticity coordinates, a lower optimal doping concentration, and equally excellent thermal stability. The satisfactory color-rendering index of packaged white-light-emitting diodes demonstrates its potential performance as a red phosphor. Briefly, this work provides not only a new case for the study of the local crystal structure and luminescence properties but also a new possibility for the application of a red phosphor in solid-state lighting.

A modified structure Ca(Mg0.8Al0.2)(Si1.8Al0.2)O6 (denoted as CMASO) from the evolution of CaMgSi2O6 (denoted as CMSO) codoped with Ce3+ and Tb3+ ions was designed successfully by solid reaction method for application in phosphor-converted white-light-emitting diode (pc-wLED). The Rietveld refinement of these two structures verified the changes derived from the replacement of some of the Mg2+ and Si4+ ions by Al3+ ions. The band gaps were calculated by density-functional theory (DFT) calculation method to verify the change of Al3+ ions replacing further, and the diffuse reflectance spectra (DRS) proved the veracity of the calculation result. The phosphors CMASO:Ce3+ showed blue emission excited by a wider excitation wavelength from 280 nm to 370 nm. The change of structure lead to the absorbable range broaden and the emission peak shifted to longer wavelength, compared with CMSO:Ce3+, although the amount of emitting center was the same. The reason for these phenomena was discussed in detail. The codoped phosphors CMASO:Ce3+,Tb3+ exhibited different emission colors from blue to green as the concentration of Tb3+ ions increased. Combined with commercial red phosphor CaAlSiN3:Eu2+ and ultraviolet LED (UV-LED) chips, the selected appropriate samples achieved white emission. The correlated color temperature (CCT) was 6137 K and the color rendering index (Ra) was 80.5, indicating that they could act as potential phosphors for possible applications in pc-wLED.

Warm white light-emitting diodes (WLEDs) with low correlated color temperature (CCT < 5000 K) have a wide range of applications in solid-state lighting. This work reports Y2Mg2Al2Si2O12 (YMAS):Ce3+,Mn2+ phosphors for warm WLEDs, which are suitable for current mainstream blue LED chips (λ = 460 nm). The crystal structure and site occupation of the synthetic materials conforms to the design, and they are studied experimentally and computationally. The spectral red shift of YMAS:Ce3+,Mn2+ phosphors can reach up to 77 nm compared with the commercial YAG:Ce phosphor. Their comparatively excellent thermal stability and good chromaticity stability are proved. Theoretically, this series of phosphors, combined with blue chips, can achieve almost the whole area of warm white light emission. Their practical application performance in LEDs is demonstrated, and the CCT of the LEDs achieves an effective optimization (∼4000 K). The simple synthetic method, effective color point tuning and good stability make YMAS:Ce3+,Mn2+ an attractive candidate phosphor for warm white LED lighting.

In this paper, hollow double-shelled TiO2:x%Eu3+@SiO2:y%Tb3+ nanospheres (C1–Ti-x/Si-y) were fabricated using carbon spheres as hard template followed by a two-step sol–gel coating process. The res...

Leveraged loan has become an import risk contributor to the wholesale portfolio of a financial institution and an accurate evaluation of the recovery rate of leveraged loans is crucial for risk-based decision making by banks. To achieve this, we utilize a simple two-stage model framework conditional on loan and its borrower's characteristics. Under this framework, three kinds of models and two combining mechanisms are studied by using a subset of leveraged loan data filtered from Moody's Ultimate Recovery Data (URD). The in-sample and out-of-sample results show that three-split model with parallel combining mechanism yields more accurate predictions of ultimate recovery rates for leveraged loans. It is shown that the percentage of debt that is junior relative to the issuance in the issuer's capital structure is the most important determinant of the leveraged loan recovery outcomes. Recovery rates for Leveraged loans and for non-leveraged-loan debts are also compared. Empirical studies show that they have different influential factors.

The color point tuning is significant for expanding the application of optical materials (phosphors). In this work, one type of single Eu2+-activated high bright phosphor was prepared, and the colo...

A series of Dy3+/Eu3+ ions doped Ca2(Mg0.75Al0.25)(Si1.75Al0.25)O7 (denote as CMAS) phosphors were synthesized by conventional high temperature solid-state reaction method. The crystal phase was characterized by X-ray diffraction and crystal structure refinement employed the Rietveled method. The luminescence properties of CMAS host, CMAS:Dy3+/Eu3+ and CMAS:Dy3+,Eu3+ phosphors were researched. The energy transfer phenomenon from CMAS host to Dy3+/Eu3+ ions in CMAS phosphors and from Dy3+ to Eu3+ ions in co-doped CMAS phosphors was studied and confirmed. The energy transfer efficiency was calculated and the energy transfer mechanism was identified. The color tunability and thermal stability were researched. All the studies of CMAS:Dy3+,Eu3+ phosphors showed a great potential application for solid state lighting and display application.

A novel luminescence material of emitting color-tunable Ca20Al26Mg3Si3O68 (denoted as CAMSO):Ce3+,Tb3+ phosphors have been synthesized via the high temperature solid-phase reaction process. The crystal cell structure, photoluminescence properties and application performance such as thermal stability and LED device performance of the phosphors were researched in detail. CAMSO:Ce3+,Tb3+ phosphors showed multicolor with the different concentration of Ce3+ and Tb3+ ions. Although the concentration of Ce3+ ions was settled and there was the existence of energy transfer from Ce3+ to Tb3+ ions, it was found that Ce3+ ions’ blue light emission intensity showed abnormal increasing with the increase of Tb3+ ions doping concentration. The irregular phenomenon was discussed in detail. The phosphor CAMSO:0.2Ce3+,0.1Tb3+ photoluminescence emission intensity motivated by 374 nm at 150 °C retained about 81% of that measured at room temperature, which demonstrating the good thermal and color stability of the sample. In ad...

A series of promising color-tunable Ca20Al26Mg3Si3O68 (CAMSO):Eu phosphors have been synthesized by a high-temperature solid-state method. Both Eu2+ and Eu3+ ions exist in this system despite the samples prepared in a reducing atmosphere. This phenomenon was discussed according to the thermal stability of the samples and the change of the local structure with Eu2+ ion doping. Furthermore, the multiple emissions of the Eu2+ ion in the CAMSO:Eu phosphors arise from Eu2+ ions at distinct crystallographic sites. The low-temperature emission spectra were investigated in detail by Gaussian peak parting to ascertain the site occupation of the Eu2+ ions. LEDs were fabricated using the CAMSO:xEu (x = 0.1, 0.2, 0.4, and 0.6) with 380 nm chips. The emission color could be tuned continuously from blue to yellow by increasing the concentration of Eu ions. A higher color rendering index (Ra > 80) and a broader color gamut could be achieved, indicating the promising application potential of the CAMSO:Eu phosphors for white LEDs.

Multi-color single-phase white emission Sr 3 B 2 SiO 8 :Tm 3+ /Dy 3+ /Eu 3+ fluorescent powders were prepared by solid-state fritting method. The fluorescence performance of Tm 3+ , Dy 3+ and Eu 3+ ions single-activated Sr 3 B 2 SiO 8 phosphors were investigated and they exhibit desirable behaviors in their characteristic emissions. Meanwhile, the energy required for migration from Tm 3+ to Dy 3+ and from Dy 3+ to Eu 3+ in co-doped fluorescent substance was determined by the aids of steady-state and transient-state photoluminescence spectra /decay measurements. The energy transmission process from Tm 3+ to Dy 3+ and Dy 3+ to Eu 3+ has been explored to be a dipole–quadrupole interaction and a dipole-dipole interaction of the resonant type, respectively. More significantly, by tuning the molarity ratio of doping Dy 3+ /Eu 3+ ions, multicolor emission from yellow to red shall be achieved in Sr 3 B 2 SiO 8 :Dy 3+ , Eu 3+ phosphors for its potential adhibitions in solid-state lighting applications. The Sr 3 B 2 SiO 8 :Tm 3+ , Dy 3+ samples can implement white light emission by the appropriate changeable doping molar quantity of Tm 3+ and Dy 3+ , applying potentially in white LEDs. The energy migrations between co-doped rare earth ions play a decisive role in these processes.

Color-tunable phosphors can be obtained through codoping strategies and energy transfer regulation. Ce

Arsenic (As) is a problematic pollutant that can cause cancer and other chronic diseases due to its potential toxicity. Iron (oxyhydr)oxides can readily sorb As and play important roles in the geochemical cycle of As. Attention has mainly been given to the affinity and mechanism of As sorption by synthetic pure iron (oxyhydr)oxides, and little is known about the relationship between As behavior and multicomponent secondary iron minerals (SIMs) naturally formed in acid mine drainage (AMD). To investigate this relationship, we performed sorption kinetics, isotherm and competitive sorption experiments to investigate As(V) sorption behaviors on naturally formed SIMs harvested from different runoff zones of an abandoned coal mine. Several spectroscopic analyses were used to evaluate the structural and component changes and phase transformation. Three environmental SIMs formed at nascent (n-SIM), transient (t-SIM) and mature (m-SIM) stages were determined to be similar in the element components of Fe, S and O but different in structure. As(V) sorption behaviors on these environmental SIMs followed a pseudo-second-order kinetic model, and the sorption extent followed the sequence of n-SIM > t-SIM > m-SIM. As(V) sorption is not significantly influenced by Na+/Ca2+ concentration or ionic strength except for that of PO43−, and it slightly decreases as the Cr(Ⅲ) concentration increases but increases with increasing Sb(Ⅲ)/(V) concentration. The results of spectral analyses indicate that As(V) immobilization mainly depends on exchange with SO42− and surface complexation, along with the phase transformation of schwertmannite/jarosite to goethite and other phases. These findings are helpful for better understanding the geochemical behaviors of As(V) associated with environmental SIMs.

Excellent luminous performance and high color rendering are the keys to white light-emitting diode (WLED) illumination. This work reports a single-phase full-visible-spectrum Y2Mg2Al2Si2O12(YMAS):Eu2+,Mn2+ phosphor for WLEDs with ultra-high color rendering. The luminescence of a single Mn2+ doped YMAS phosphor is very weak due to the spin-forbidden transition of Mn2+, while it can be dramatically enhanced in the YMAS:Eu2+,Mn2+ system through efficient energy transfer from the sensitizer Eu2+. Meanwhile, the luminescent color of this phosphor can be tuned from cyan to cold white, to warm white, and finally close to the yellow region by controlling the activator concentration and energy transfer process. Its good thermal and chromaticity stability meet the requirements of application in WLEDs. Its stable photochromic performance at different excitation wavelengths (365-395 nm) indicates that it can be used in different ultraviolet chips. The YMAS:0.03Eu2+,0.30Mn2+ phosphor-converted WLED achieves an ultra-high color rendering index (Ra = 93.3), near-standard chromaticity coordinates (CIE = (0.3343, 0.3388)) and a suitable correlated color temperature (CCT = 5417 K).

Phosphors with excellent color adjustable properties have always been the research focus of scientific researchers. This work uses two strategies to control the luminescence behavior of Eu2+ ions in the Lu2Mg2Al2Si2O12 (LMAS) matrix. Firstly, by adjusting the Eu2+ ion concentration, the emission spectra of Lu2Mg2Al2Si2O12:Eu2+ (LMAS:Eu2+) could achieve a 39 nm red shift from 451 to 490 nm, which provides a good blue to cyan emission. Secondly, the Lu2Mg2Al2Si2O12:Eu2+,Mn2+ (LMAS:Eu2+,Mn2+) realized the tuning from the cyan to the white region by introducing Mn2+ ions, which is owing to the sensitization process of Eu2+ to Mn2+ enhancing the red-light emission. The energy transfer process was explored in detail, and the energy transfer efficiency was calculated to be more than 60%. Meanwhile, the thermal stability of the material was also studied. The thermal stability illustrates its potential application in white light-emitting diode (WLED). Under 30 mA drive current, the device obtained by using 365 nm ultraviolet (UV) chip with LMAS:0.01Eu2+,0.35Mn2+ phosphor has a color rendering index (Ra) as high as 93.1, R9 = 85, LE = 1.81 lm/W, the color coordinate is (0.3076, 0.3119) and the correlated color temperature (CCT) is 6984 K, which is obviously in the white light area. The above results indicate that LMAS:Eu2+,Mn2+ phosphors with full-visible-spectrum have potential applications in solid-state lighting.

Here, the crystal structure, phase analysis, site occupancy, and luminescence properties of NCMP:Eu

Structure determines properties, and properties determine applications, which is an important ideology of natural sciences. For optical materials, it is vital to lucubrate the corresponding relationship between the local crystal structure and luminescence properties for their design, synthesis, and application. This work reports a newly designed Y

A modified structure Ca(Mg

Energy transfer and pressure-driven color tuning phosphor Mg2Gd8(SiO4)6O2:Ce3+ (MGS:Ce3+), with ultra-wideband spectra was synthesized by high-temperature solid-state method. When the phosphor was excited by ultraviolet light, it emitted a sort of cold near-white light. The photoluminescence emission (PL) and excitation (PLE) spectra, luminescence sites of MGS:Ce3+ had been researched. In order to adjust the light color to achieve the purpose of spectral tuning, two methods had been implemented. The first method was doping Mn2+ into MGS:Ce3+. There was energy transfer from Ce3+ to Mn2+ in such phosphor, and the energy transfer had been researched in detail. After doping with Mn2+, the color coordinates positions and correlated color temperature (CCT) of phosphors were improved obviously. When fixed the concentration of Ce3+ and the doping concentration of Mn2+ is y = 1.0, 2.0 and 3.0, the phosphor can realize the warm white light emission. The second one was applying pressure to MGS:Ce3+, expecting to achieve the above purpose through the red shift of the spectrum. The results showed that the sample could withstand the high pressure of 26.03 GPa. A relatively rare phenomenon of pressure enhancement emission appeared when the pressure was between atmospheric pressure and 3.17 GPa. When the pressure exceeded 3.17 GPa, the luminescence intensity decreased regularly with the increase of pressure and the phosphor showed high pressure sensitivity (dλ / dP ≈ 1.8453 nm GPa−1). What’s more, the sample at compression environment made a significant red-shift about 60 nm of the emission bands. In the process of compression, the color coordinate shows that the light color of phosphor can be adjusted from blue-green light to yellow light region under the excitation of 355 nm. All above results revealed that the convenient synthetic method, effective light color coordinating made the MGS:Ce3+ and MGS:Ce3+,Mn2+ become a potential phosphor for (warm) white light. What’s more, the emission spectra red shift resulting from pressure change made it possible to be a potential optical pressure sensor.

A series of mesoporous SiO2 nanoparticles (MSNs) have been synthesized by a modified sol–gel process. The morphology could be manipulated from flower-like nanospheres to flower-like nanodisks, circular nanodisks and sunken nanovesicles by simply adjusting the amount of ammonia. Among the various morphologies, the flower-like nanospheres (N1) with a large specific surface area of 1037.16 m2 g–1 exhibited the highest and fastest adsorption capacity for dye-RhB because of the most complex surface structure (234.61 mg g–1, approximately 90% in the first 5 min). The RhB adsorption processes on different MSNs were explained by Langmuir, Freundlich and Temkin isotherm models, and a transition from multilayer adsorption to homogeneous adsorption was achieved. The adsorption kinetics was in accord with the pseudo-second-order model, suggesting the rate-limiting step of RhB on MSNs was mainly chemical process. The luminescence properties of different samples revealed that the nanovesicles structure (N5) exhibited t...

A series of emission-tunable Ce3+/Tb3+/Eu2+ doped Ca2(Mg0.75Al0.25)(Si1.75Al0.25)O7 (denoted as CMAS) phosphors have been synthesized via a high temperature solid-state reaction method. The luminescence properties, color tuning, quantum yields (QYs), energy transfer of Ce3+ to Tb3+/Eu2+, thermal stability, performance of LED devices and ratiometric temperature sensing application have been systematically investigated, respectively. Importantly, through the study of thermal stability, we found that Ce3+ and Tb3+ co-doped samples were suitable for WLED applications, while Ce3+ and Eu2+ co-doped samples were suitable for temperature sensing applications. Due to the energy transfer, Ce3+/Tb3+ co-doped samples had high luminous efficiency and the quantum efficiency of more than 80% could be achieved. Their emission colors can modulate from blue to green. In addition, on the basis of the evaluation of the as-fabricated white LED lamps via selecting the corresponding phosphors, the CCT can reach 4275 K and the CRI can increase to 86.8, indicating that this series of phosphors can act as potential color-tunable phosphors for possible applications in ultraviolet light based white LEDs. Importantly, it is found that the fluorescence intensity ratio of CMAS : 5%Ce3+,0.5%Eu2+ displays linear correlation with temperature in a wide range of 253–373 K with a high sensitivity of 2.49% K−1, indicating that it could be a good candidate for ratiometric optical thermometry.

Sm 3+ doped TiO 2 nanocrystals with various morphologies were fabricated via a facile hydrothermal route, and the effect of morphology on the luminescence properties and photocatalytic activity of the products has been investigated. PL studies on TiO 2 :Sm 3+ revealed that the sensitized emission is a much more efficient pathway than the direct excitations of Sm 3+ . Combined 10 K spectra and theoretical analysis, several kinds of sites of Sm 3+ ions have been found in TiO 2 matrix. Most importantly, structural models for the formation of multiple sites are proposed based on the optical behaviors of Sm 3+ at different sites. Photocatalytic results suggest that flower-like hierarchical architectures show the highest photocatalytic activity compared with nanorods samples with different aspect ratios, and the photodegradation efficiency was 96.8% after 20 min for degradation of methyl orange under white light irradiation. And surface photovoltage spectroscopy (SPV) have been measured to understand the separation and transfer behaviour of photogenerated charges which are helpful for explaining the photocatalytic and luminescence properties deeply. Moreover, TiO 2 :Sm 3+ @TiO 2 luminescent enhancement homo-structures and TiO 2 :Sm 3+ @SiO 2 luminescent enhancement hetero-structures are prepared. The effect of calcination temperature on luminescence intensity and the luminescence enhancement mechanism have been discussed in detail.

Zn 2 SiO 4 :Eu 3+ phosphors with diverse morphologies, including rice-like, hexahedron-like, and column-like, have been successfully prepared by means of a simple hydrothermal approach followed by a subsequent calcinations process. The results indicate that the morphologies of the products can be adjusted by altering the pH value of the reaction system. The formation mechanisms of different morphologies of samples have been investigated in detail. Furthermore, under near ultraviolet excitation, the Zn 2 SiO 4 :Eu 3+ exhibits strong red emission corresponding to the 5 D 0 → 7 F 2 transitions of the Eu 3+ ions, which have potential applications in optical and biological areas. Meanwhile, luminescent characteristics of different morphologies have been explored and the column-like Zn 2 SiO 4 :Eu 3+ sample presents an optimum red luminescence. The CIE chromaticity diagram and the symmetry of the different morphologies phosphors also have been explored. In addition, the concentration quenching effects and decay kinetics behaviors of Zn 2 SiO 4 :Eu 3+ microstructures with optimum red luminescence were investigated and the strongest luminescent intensity and the longest lifetime were both in the composition of 0.03 mol Eu 3+ .

A series of novel color tunable dandelion-like SiO2:Ln3+ (Ln = Eu, Tb) nanophosphors of approximately 70 nm diameter were prepared using a simple hydrothermal route. The phase, time-dependent shape evolution, morphology, sizes, and luminescence properties of the as-prepared products were well characterized by means of X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, and photoluminescence spectra as well as kinetic decay curves. Under ultraviolet excitation, the Eu3+ and Tb3+ singly doped SiO2 samples showed strong red and green emission, respectively. Furthermore, the luminescence colors of the as-prepared Tb3+, Eu3+ co-doped dandelion-like SiO2 nanophosphors could be altered from green to red, including green-yellow, yellow, orange yellow and reddish orange, by simply adjusting the doping concentrations of Eu3+.

The single-phase Ba3Sc(BO3)3:Ce3+/Tb3+ samples were synthetized via high-temperature solid-state reaction. X-ray diffraction (XRD), Rietveld refinement and transmission electron microscopy (TEM) were used for characterizing the morphology and phase purity of Ba3Sc(BO3)3. The photoluminescence emission (PL) and excitation (PLE) spectra, lifetime decay behavior and thermal stability of the Ba3Sc(BO3)3:Ce3+/Tb3+ phosphors were discussed in detail. Site occupation of Ce3+ ions in Ba2+ and Sc3+ sites were explained through Gaussian fitting and Van Uitert empirical equation. All these properties are closely related to the intrinsic crystallization structure of the Ba3Sc(BO3)3 matrix, which is discussed in detail in this paper. Compared with Ba3Sc(BO3)3:1%Tb3+ sample, the luminous intensity of Tb3+ increased about 3.2 and 4.1 times for Ba3Sc(BO3)3:2%Ce3+,1%Tb3+ monitored at 342 and 313 nm, respectively. Energy transfer (ET) mechanism of Ce3+→Tb3+ were dipole-dipole interactions and quadrupole-quadrupole interactions at Ce3+(1) and Ce3+(2) sites, respectively. The temperature-dependent PL spectra of Ba3Sc(BO3)3: Ce3+,Tb3+ illustrated that this phosphor possesses excellent thermal stability and chromaticity stability. Finally, a white LED device was prepared via the combination of the n-UV chip (365 nm), commercial blue BAM:Eu2+ phosphor, green Ba3Sc(BO3)3:2%Ce3+,6%Tb3+ phosphor and commercial red Sr2Si5N8:Eu2+ phosphor, which showed bright warm-white light. These conclusions proved that the green Ba3Sc(BO3)3:2%Ce3+,6%Tb3+ phosphor is desirable for white LED applications.

A series of emission-tunable Ce

A series of (Ba0.9Sr0.1)9Lu2Si6O24: Eu2+, Mn2+ phosphors have been synthesized by a solid-state reaction. The occupied position of rare earth ions can be successfully changed through Sr2+ ions replacing Ba2+ ions partly, therefore, the corresponding optical properties can be tuned. When Sr2+ ions replace Ba2+ ions by 10%, Eu2+ ions occupy not only alkaline earth 1(AE1) site to produce a blue emission bands centered at 460 nm but also AE2/AE3 site to generate a green emission bands centered at 520 nm, both of which are ascribed to the 4f65d1-4f7(8S7/2) transition of the Eu2+ ions. When co-doping Mn2+ ions, red broad emission centered at 595 nm originated from the 4T1(4G)-6A1(6S) transitions of Mn2+ ions can be added to the emission spectra of co-doped phosphors. There is energy transfer from Eu2+ to Mn2+ ions in the (Ba0.9Sr0.1)9Lu2Si6O24 host that have been confirmed to be a dipole-dipole interaction. The luminescent color from cool white to warm white even to orange-red can be adjusted by proper controlling the Mn2+ ions doping concentration. Furthermore, an excellent white LED device has been fabricated consisting of (Ba0.9Sr0.055)9Lu2Si6O24: 0.03Eu2+, 0.015Mn2+ phosphor and a 370 nm NUV-chip. This device presented an excellent correlated color temperature (CCT) of 4631 K and a high color-rendering index (CRI) of 83, indicating that the co-doped (Ba0.9Sr0.1)9Lu2Si6O24: Eu2+, Mn2+ phosphors will be a promising candidate as a single-phase, color-tunable phosphors for NUV-based white-light emitting diodes.

This paper presents galloping analysis of multiple-degree-of-freedom (MDOF) structural roofs with multiple orientations. Instead of using drag and lift coefficients and/or their combined coefficient in traditional galloping analysis for slender structures, this study uses wind pressure coefficients for wind force representation on each and every different orientation roof, facilitating the galloping analysis of multiple-orientation roof structures. In the study, influences of nonlinear aerodynamic forces are considered. An energy-based equivalent technique, together with the modal analysis, is used to solve the nonlinear MDOF vibration equations. The critical wind speed for galloping of roof structures is derived, which is then applied to galloping analysis of roofs of a stadium and a high-rise building in China. With the aid of various experimental results obtained in pertinent research, this study also shows that consideration of nonlinear aerodynamic forces in galloping analysis generally increases the critical wind speed, thus enhancing aerodynamic stability of structures.

Wind exposure categories are currently used to account for the influences of different ground roughness in wind profile that is fundamentally important to wind-resistant structural analysis and design. Since each classified exposure covers a relatively large spectrum of ground roughness with constant indices such as exponent α , this results in uncertain wind-resistant structural analysis and design for structures in each and every categorized exposure. More importantly, such an uncertainty is not only quantitative but also qualitative in terms of aerodynamic instability assessment and economic loss estimation. This study proposes a method to determine the actual wind exposure and estimates its influences in wind-resistant structural analysis and design. In particular, this paper first provides a review of wind exposure categories and illustrates the shortcomings of its use in structural analysis and design. It then introduces a method to determine the actual ground exposure. The method generates formulae for the actual ground roughness exponent on the basis of measured data from both wind-tunnel and full-scale experiments, of ground roughness-induced wind energy dissipation analysis, as well as of current Chinese and other countries’ loading codes. Through examples of hypothetical and practical engineering projects, this study finally investigates the influences of the actual ground roughness exponent on wind-induced structural responses and economic loss estimation, as well as on wind-resistant structural design.

Fully Λ-doublet quantum state-resolved differential cross-sections for collisions of NO(X) with neon at a collision energy of 540 cm are presented. Initial state selection of the Ω = 0.5, j = 0.5, f Λ-doublet level of the NO(X) was achieved using hexapole focussing. Both spin-orbit level conserving and spin-orbit level changing transitions have been studied. The experimental results are compared with those obtained from quantum scattering calculations and are shown to be in excellent agreement. Quantum scattering calculations have also been performed on a modified potential energy surface with the attractive region removed, to determine the effects this has on the differential cross-sections. Comparisons are also made with the inelastic scattering of NO(X) with He and Ar. © 2013 Copyright Taylor and Francis Group, LLC.

The fully Λ-doublet resolved state-to-state differential cross sections (DCSs) for the collisions of NO(X, (2)Π, v = 0, j = 0.5) with Ar have been shown to depend sensitively on the conservation of the total parity of the NO molecular wavefunction. Parity changing collisions exhibit a single maximum only in the DCS, while parity conserving transitions exhibit multiple rainbow peaks. This behaviour is shown to arise directly from the constructive or destructive interference of collisions impacting on the two pointed ends and on the flatter middle of the NO molecule. A simple hard shell, four path model has been employed to determine the relative phase shifts of the paths contributing to the scattering amplitude. The model calculations using the V(sum) potential, together with the results of a quasi-quantum treatment, provide good qualitative agreement with the experimental spin-orbit conserving (ΔΩ = 0) DCSs, suggesting that the dynamics for all but the lowest Δj transitions are determined largely by the repulsive part of the potential. The collisions leading to spin-orbit changing transitions (ΔΩ = 1) have been also found to be dominated by repulsive forces, even for the lowest Δj values. However, they are less well reproduced by hard shell calculations, because of the crucial participation of the V(diff) potential in determining the outcome of these collisions.

Probabilistic characteristics of response of a multi-storey structure with tuned liquid dampers (TLD) installed in one or some of the floors due to random dynamic loads are investigated. The tuned liquid damper consists of crossed tube-like containers of nonlinear characteristics of energy dissipation. A new version of stochastic linearization approach is applied to solve the nonlinear vibration of the structure and the liquid in the containers. Specifically, the nonlinear vibration system is replaced by an equivalent system in terms of the criterion of minimal mean square deviation of generalized energies between these two systems. Examples given show that the modified stochastic linearization approach is closer to the exact solution than the conventional one. Finally, the effects of the tuned liquid damper on the structural response are identified.