Near-infrared luminescence of Er3+ in MoO3/WO3 modified tellurite glass.

In this work, the network structure of Er3+ doped tellurite glass was modified by incorporating MoO3/WO3 oxides and the effect of the structural modification on the near-infrared luminescence properties of Er3+ was investigated. The examination of fluorescence spectrum reveals that partial substituting TeO2 with MoO3/WO3 in the composition significantly enhances both the emission intensity and the FWHM (full width at half maximum) of the 1.53 µm band, and the improved local environment around Er3+ ions and phonon energy of glass host are considered to be responsible for these results. The XRD pattern, Raman spectrum and Judd-Ofelt intensity parameter disclosed the changes in network structure and phonon energy, the DSC curve showed an improvement in thermal stability, and fluorescence decay curve displayed the increase of Er3+ lifetime at the 4I13/2 level, all of these indicated the positive effect of MoO3/WO3 addition on the near-infrared luminescence properties of Er3+.

Improved 2†µm broadband luminescence in Tm3+/Ho3+ doping tellurite glass.

Tm3+/Ho3+ doping tellurite glasses (TeO2-ZnO-La2O3) were prepared by applying melt-quenching technique, and the ∼2.0 µm band luminescence characteristics were examined. A broadband and relatively flat luminescence at 1600 to 2200 nm was observed in the tellurite glass co-doped by 1.0 mol% Tm2O3 and 0.085 mol% Ho2O3 under the excitation of 808 nm laser diode (LD), which is the result of spectral overlapping of 1.83 µm band of Tm3+ ions and 2.0 µm band of Ho3+ ions. Further, about 103% enhancement was acquired after the introduction of 0.1 mol% CeO2 and 7.5 mol% WO3 at the same time, which is primarily caused by the cross-relaxation between Tm3+ and Ce3+ ions together with the enhanced energy transfer from the Tm3+:3F4 level to Ho3+:5I7 level due to the increase in phonon energy. Spectral characteristics associated with the radiative transition of Ho3+ and Tm3+ ions on the basis of Judd-Ofelt theory, and the fluorescence decay behaviors after the addition of Ce3+ ions and WO3 component were analyzed to understand the broadband and luminescence enhancement. The findings in this work indicate that tellurite glass with optimal Tm3+-Ho3+-Ce3+ tri-doping combination and appropriate amount of WO3 is a prospective candidate for broadband optoelectronic devices operated in the infrared bands.

Enhanced ultra-wide NIR fluorescence in tellurite glass doped with Er3+-Tm3+-Nd3+-Ag NPs.

Tellurite glasses with combination of Er3+/Tm3+/Nd3+ ions and silver nanoparticles (Ag NPs) were prepared by using single-step melt-quenching technology, and the enhanced effect of Ag NPs on the ultra-broadband near-infrared (NIR) fluorescence was studied. Under the 808 nm LD excitation, two ultra-broadband NIR fluorescence of 1300-1600 nm and 1600-2100 nm underwent an obvious enhancement of about 52% compared to the tri-doping tellurite glass free of Ag NPs. The intensified local electric field induced by Ag NPs together with the energy transfer from Ag species to doped ions is responsible for this enhancement. The enhanced ultra-broadband NIR fluorescence of 1300-1600 nm with the full width at half maximum (FWHM) of 230 nm, originating from the spectral overlapping of 1.34 µm (4F3/2→4I13/2 of Nd3+), 1.47 µm (3H4→3F4 of Tm3+) and 1.53 µm (4I13/2→4I15/2 of Er3+) three bands, is promising in developing new ultra-broadband photonic devices such as fiber amplifiers and tunable lasers.

Broad and flat dual-band NIR luminescence from Er3+/Tm3+/Ho3+ tri-doped tellurite glass.

We report the near-infrared (NIR) broadband luminescent property of tellurite glasses incorporated with Er3+, Tm3+, and Ho3+ ions. Under the excitation of a commercial 808 nm laser diode, two ultra-broadband and flat NIR luminescent bands ranging from 1350-1600 and 1600-2200 nm with respective full width at half-maximums of 153 and 374 nm. were obtained simultaneously in tellurite glass with an optimal combination of three Er3+-Tm3+-Ho3+ ions. This valuable discovery enables us to develop new, to the best of our knowledge, NIR broadband fiber amplifiers and tunable lasers which can be applied to fields such as optical communication and biomedicine.

Structural, thermal and broadband NIR emission properties of Nd3+/Pr3+/Ag NPs co-doped tellurite glass.

Nd3+/Pr3+ co-doped tellurite glasses containing metallic Ag NPs were synthesized by melt-quenching and heat-treating techniques. The amorphous structural nature, fundamental vibrational units and good thermal stability of the prepared tellurite glasses were confirmed by X-ray diffraction (XRD) pattern, Raman spectrum and differential scanning calorimeter (DSC) curve, respectively. The precipitated Ag NPs in a glass matrix with an average diameter ∼5 nm were revealed by transmission electron microscopy (TEM) image, and the radiative property of Nd3+ and Pr3+ ions was evaluated from the absorption spectrum by Judd-Ofelt theory. Under the excitation of 488 nm Xenon lamp, two broadband near-infrared emissions covering 800-1100 nm and 1250-1650 nm ranges were observed from the fluorescence spectrum. The former originated from the transitions of Pr3+:3P1,0→1G4, Pr3+:1D2→3F4,3, Nd3+:4F3/2→4I11/2 and Nd3+:4F3/2→4I9/2, while the latter was contributed by the Pr3+:1G4→3H5, Pr3+:1D2→1G4, Pr3+:3F3→3H4 and Nd3+:4F3/2→4I13/2 transitions. With the introduction of Ag NPs, the emission intensity of two broadband near-infrared emissions was further enhanced, in which the peak emission intensity of 1250-1650 nm band was increased by about 56% and the FWHM is up to 250 nm. The obtained results indicate that Nd3+/Pr3+/Ag NPs co-doped tellurite glass has great potential in realizing ultra-broadband near-infrared emission covering O-, E- and S-bands simultaneously.

Ultra-broadband 1.0 µm band emission spectroscopy in Pr3+/Nd3+/Yb3+ tri-doped tellurite glass.

Tellurite glasses doped with trivalent Pr3+, Nd3+ and Yb3+ ions were prepared using conventional high-temperature melt-quenching technique and their optical absorption, near-infrared emission, X-ray diffraction (XRD), Raman spectrum, and differential scanning calorimeter (DSC) curve were measured. Upon excitation at 488 nm, an ultra-broadband near-infrared emission extending from 800 to 1120 nm was found to appear owing to the overlapping of the emission bands centered at 900 and 1035 nm of Pr3+, 880 and 1060 nm of Nd3+ as well as 978 nm of Yb3+, respectively. The energy transfer mechanism among Pr3+, Nd3+ and Yb3+ ions which was responsible for the observed ultra-broadband near-infrared emission was investigated to understand the luminescent phenomena. In addition, Judd-Ofelt theory was applied to predict the radiative properties of doped rare-earth ions, and some important radiative parameters such as radiative transition probability, branching ratio and radiative lifetime were derived. Meanwhile, the structural information of amorphous nature and vibrational units was revealed by the XRD pattern and Raman spectrum. Also, the DSC curve displayed the good thermal stability to resist thermal damage for studied tellurite glass with high glass transition temperature. The results indicate that Pr3+/Nd3+/Yb3+ tri-doped tellurite glass is a promising material for ultra-broadband fiber lasers operating around 1.0 µm near-infrared band.

[Immunoregulatory effect of artesunate on allergic contact dermatitis and its mechanism].

This study is to elucidate the immunoregulation mechanisms of artesunate (AST) on allergic contact dermatitis (ACD). Pharmacodynamics analyses, HE staining, semi-quantitative RT-PCR and Western blotting were used to explore the effects of AST on the related cytokines, transcription factor and signaling molecule of ACD respectively. The results indicated that topical administration of AST not only reduced the increase of ear swelling, spleen index and inflammatory cells infiltration in ACD mice, but also inhibited remarkably the expression of IFN-gamma, T-bet and NF-kappaB p65. It's suggested that AST could exhibit suppressive effects on inflammatory response and immune function of ACD, which indicates the possibility of developing AST as a novel immunoregulatory agent in the treatment of ACD and other immune-related diseases.

Anti-inflammatory and immunomodulatory mechanisms of artemisinin on contact hypersensitivity.

Artemisinin (Art) is a sesquiterpene trioxane lactone from Artemisia annua L., which has been shown to affect immune responses. However, the underlying mechanism remains elusive. In this study, we examined the anti-inflammatory and immunomodulatory effects of Art in a mouse model of contact hypersensitivity (CHS), a T-cell-mediated cutaneous inflammatory reaction. The data showed that topical administration of Art could suppress CHS response and Con A-induced T cell proliferation effectively. Further experiments indicated that Art induced the generation of regulatory T cells (Tregs) and impaired the phosphorylation of AKT, associated with the up-regulation of p38 MAPK activation. Moreover, Art also exerted a strikingly inhibitory effect on IL-17 production, and diminished the level of IL-6 paralleled with an enhancement of TGF-ß, which effects were coupled with a significant reduction of STAT3 activation. These data reveal that Art could effectively block CHS response in mice by inducing the generation of Tregs and suppressing the development of Th17, indicating the potential of Art to be applied as an effective therapeutic agent for treating immune-related diseases.

State-selective energy transfer from Er3+ to Eu3+ in Bi2O3-GeO2-Ga2O3-Na2O glasses.

The Eu(3+) ion was introduced into Er(3+) doped Bi(2)O(3)-GeO(2)-Ga(2)O(3)-Na(2)O (BGGN) glasses to improve the 1.5 microm band emission. As a function of Eu(2)O(3) doped content, we observed the increase in non-radiative decay rate of Er(3+) not only (4)I(11/2) energy level but also (4)I(13/2) energy level, while the lifetime of Er(3+):(4)I(11/2) and (4)I(13/2) levels were shortened from 607 to 241 micros and from 3.37 to 1.88 ms, respectively. Accordingly, the upconversion fluorescence (green and red) was quenched. The total quantum efficiency of the Er(3+):(4)I(13/2) increased with the Eu(2)O(3) content increasing up to 0.2 mol% due to the state-selective energy transfer from Er(3+) to Eu(3+).