Synthesis and Luminescence Properties of(Y, Gd)(P, V)O_4:Eu^(3+), Bi^(3+) Red Nano-phosphors with Enhanced Photoluminescence by Bi^(3+), Gd^(3+) Doping

A series of(Y_(1-y), Gdy)_(0.95-x)(P_y, V_(1-y))O_4 :0.05Eu^(3+), xBi^(3+)+phosphors have been successfully prepared by a subsection method. The crystal structure, surface morphology and luminescence properties were investigated. It was found that the sintered samples crystallized in a tetragonal crystal system with space group I_(41)/amd(a = b = 0.7119 nm, c = 0.6290 nm). The products presented rod-like morphology with length of 100-150 nm and width of 50-100 nm. A maximum peak at 619 nm(~5D_0 →~7F_2) was observed in emission spectrum of the phosphors. It was also found that co-doping of Bi^(3+)+, P5+and Gd^(3+)ions into YVO_4:Eu^(3+)can not only made the right edge of the excitation band shift to the long-wavelength region, but also increased the emission intensity at 619 nm sharply and decreased the lifetime of fluorescence decay. These results may expand the application scope of the phosphors.

Ordered mesoporous carbon spheres assisted Ru nanoclusters/RuO_(2) with redistribution of charge density for efficient CO_(2) methanation in a novel H2/CO_(2)fuel cell

Efficiently reducing carbon dioxide(CO_(2))into carbon chemicals and fuels is highly desirable due to the rapid growth of atmospheric CO_(2)ncentration.In prior work,we described a unique H/CO_(2)fuel cell driven by low-valued waste heat,which not only CO_(2)nverts CO_(2)to methane(CH_(4))but also outputs electrical energy,yet the CO_(2)reduction rate needs to be urgently improved.Here,a novel Ru-RuOcatalyst with heterostructure was grafted on mesoporous carbon spheres by in situ partially reducing RuOinto ultrasmall Ru clusters(~1 nm),in which heteroatom-doped carbon spheres as a matrix with excellent CO_(2)nductivity and abundant pores can not only easily CO_(2)nfine the formation of Ru nanocluster but also are beneficial to the exposed active sites of Ru CO_(2)mplex and the mass transport.CO_(2)mpared to pure RuOnanoparticles supported on carbon spheres,our CO_(2)mposite catalyst boosts the CO_(2) nversion rate by more than 5-fold,reaching a value of 382.7μmol gcat.h-1at 170℃.Moreover,a decent output power density of 2.92 W mwas obtained from this H2/CO_(2)fuel cell using Ru-RuOembedded carbon spheres as a cathode catalyst.The Ru-RuOheterostructure can modify the adsorption energy of CO_(2)and induce the redistribution of charge density,thus boosting CO_(2)reduction significantly.This work not only offers an efficient catalyst for this novel H_(2)/CO_(2)fuel cell but also presents a facile method to prepare Ru nanoclusters.

Immunotoxicity and hepatotoxicity of PFOS and PFOA in tilapia(Oreochromis niloticus)

Perfluorinated organic compounds(PFOCs) are emerging persistent organic pollutants(POPs) widely distributed in the environment,wildlife and human.We studied the toxicology of perfluorooctane sulfonate(PFOS) and perfluorooctanoic acid(PFOA) on immunotoxicity and hepatotoxicity in primarily cultured hepatocytes of freshwater tilapia(Oreochromis niloticus).Cultured hepatocytes were exposed to PFOS or PFOA(0,10,20 and 30 mg/L) for 24,48,72,96,120 and 144 hours,respectively.Oral doses of these compounds that induce significantly detectable immunotoxicity and hepatotoxicity were employed in the study.In response to PFOS,the leukocytes,B cells,granulocytes,and macrophages among the isolation of intrahepatic immune cells(IHIC) from PFOS-treated tilapia produced significant levels of immune cells compared with that of the control group.The numbers of leukocytes,B cells,granulocytes,and macrophages for PFOS-treated tilapia increased with the incremental exposure concentration.Moreover,similar to the findings in PFOA toxicity effects,the erythropoietin levels in tilapia increased with the increase of the PFOS and PFOA concentrations.The lowest doses(10 mg/L) of PFOS exposure led to a marked inhibition in the hepatocyte viability in tilapia.Similarly,tilapia exposed to PFOA demonstrated a similar pattern,and a dose-dependent decrease in the hepatocyte viability was observed in the following treatment of PFOA.In the 72 h exposures,ethoxy-resorufin-O-deethylase(EROD) activity was significantly induced with the increase concentrations in tilapia liver(p<0.05).Tilapia showed a strong EROD induction in livers,and significantly difference in EROD activity was observed between control,PFOS and PFOA-exposed tilapias.The liver glycogen content showed that PFOS and PFOA exposure caused significant changes in the liver glycogen content,which depended on the duration of exposure.And it appeared that the decrease in blood glucose level during the acclimation was followed by significant increase in liver glycogen content in tilapia.

Preparation and upconversion luminescence of monodisperse Gd_2O_3:Ho^(3+),Yb^(3+)nanocrystals

Gd2O3：Ho^3＋,Yb^3＋ nanocrystals were synthesized via solvothermal method. X-ray diffraction （XRD）, transmission electron microscopy （TEM）, absorption and upconversion spectra were employed to characterize the synthesized nanocrystals. The results of XRD and TEM showed that obtained Gd2O3：Ho^3＋,Yb^3＋ nanocrystals were cubic in crystal structure and uniform spherical in morphology. The average crystallite size was calculated to be 7.5 nm. Green and red up-conversion emissions corresponding to （^5F4, ^5S2）→^5I8 and ^5F5→^5I8 transition were observed upon 980 nm excitation at room temperature. The results indicated that both green and red luminescence were based on the two-photon processes. Laser power and doping concentration dependence of the up- converted emissions were studied to understand the upconversion mechanisms. Excited state absorption and energy-transfer processes were discussed as the possible mechanisms for the visible emissions.

Spectroscopic properties of Gd_2O_3:Dy^(3+)nanocrystals

Gd203：Dy3＋ nanocrystals were synthesized via solvothermal method followed by a subsequent calcination. The samples were characterized by X-ray diffraction （XRD）, transmission electron microsopy （TEM）, Electronic dispersive X-ray spectroscopy （EDX）, photoluminescence （PL） spectrum and decay curves. The effect of the annealing temperature on the crystallinity and particle size was studied; heat treatment improved the crystallinity of as-prepared nanocrystals as well as increased their particle size. The nanocryatals presented monodispersed spherical shape under TEM. Photoluminescence spectra showed that nanocrystal exhibited strong yellow emission corresponding to 4F9/2----6HI3/2 transition （573 nm） of Dy3＋ under UV light excitation, which broadened with the particle size decreased without structure changed. The theoretical mechanism of luminescence was explored and surface effect was thought to be the main reason.

A Cross-linked Polyethylene with Recyclability and Mechanical Robustness Enabled by Establishment of Multiple Hydrogen Bonds Network via Reactive Melt Blending

Physical cross-linking by hydrogen-bonds (H-bonds), providing a good combination of application properties of thermosets and processability of thermoplastics, is a potential strategy to resolve the recycling problem of traditional chemically cross-linked polyethylene. However, ureidopyrimidone (UPy), the most widely used H-bonding motif, is unfavorable for large-scale industrial application due to its poor thermal stability. In this work, H-bonds cross-linked polyethylene was successfully prepared by reactive melt blending maleic anhydride grafted polyethylene (PE-g-MAH) with 3-amino-1,2,4-triazole (ATA) to form amide triazole ring-carboxylic acid units. Triazole ring can easily generate multiple H-bonds with carboxylic acid and amide. More importantly, these units are more thermal stable than UPy due to the absence of unstable urea group of UPy. The introduction of H-bonds cross-linking leads to an obvious improvement in mechanical properties and creep resistance and a good maintain in thermal properties and recyclability. Furthermore, the reinforcement effect monotonically improves with increasing the density of H-bonds. The obtained good properties are mainly attributed to largely enhanced interchain interactions induced by H-bonds cross-linking and intrinsic reversibility of H-bonds. This work develops a novel way for the simple fabrication of H-bonds cross-linked PE with high performance through reactive melt blending.

Thermal degradation of BaAl_2Si_2O_8:Eu^(2+) phosphor excited by near ultraviolet light

Eu2+ doped BaAl2Si2O8 phosphor was synthesized by one-step calcination of precursors that were prepared by chemical co-precipitation.The thermal degradation properties of BaAl2Si2O8:Eu2+ were investigated by photoluminescence,lifetime and chromaticity coordinate measurements.BaAl2Si2O8:Eu2+ is efficiently excited by incident light of 250-400 nm,which matches the emission of near ultraviolet LED chips well.BaAl2Si2O8:Eu2+ exhibits broad blue emission at 470 nm because of the 4f65d1-4f7(8S7/2) transition of Eu2+ ions,and the emission band shows an unusual blue shift with bandwidth broadening and emission intensity decreasing as the annealing temperature is increased.The luminescence decay and CIE chromaticity coordinates of BaAl2Si2O8:Eu2+ were determined to investigate its application in white LEDs.