Investigation on Spectral Characteristic and Threshold Behavior of Network Structure of Ge-Sb-S Chalcogenide Glasses.

Two series of chalcogenide glasses in Ge-Sb-S ternary system were synthesized with melt-quenching method. The phycochemical properties and spectral characteristic of glasses with different content of Ge and Sb were obtained with a series of measurements, and the systematic analysis on the change of optical properties was conducted in terms of microstructure of glasses combined with the Raman spectra. With constraint theory based on mean coordination number (Z), we described the variation trend of network structure directly. It was found that as long as the value of Z reaches 2.6, new vibration peaks would be formed in the Raman spectra indicating the presence of threshold behavior as well as the change of the network structure of the Ge-Sb-S glasses which could be expressed in a specific varition in the number of metal bonds and the nonmetal bonds. The appearance of new functional groups in the network have changed the total bond energy of glasses, and then affected the energy band structure of glasses representing the corresponding threshold behavior of the value of optical band gap (Eopg).

Quantum cutting in Pr3+-Yb3+ codoped chalcohalide glasses for high-efficiency c-Si solar cells.

Downconversion materials, which can convert one high-energy photon to two low-energy photons, have provided a promising avenue for the enhancement of solar cell efficiency. In this work, the Pr3+-Yb3+ codoped 25GeS2-35Ga2S3-40CsCl chalcohalide glasses were synthesized in a vacuumed silica ampoule by the melting-quenching technique. Under 474 nm excitation, the visible and near-IR emission spectra reveal the energy transfer from Pr3+ to Yb3+ ions, resulting in the intense 1008 nm near-IR emission for the c-Si solar cells. By tuning the excitation laser power, it is determined that one visible photon has been cut into two near-IR photons during the energy transfer process. With the help of an integrated sphere, the real quantum yields of near-IR emissions were calculated. For the 0.2Pr2S3-0.2Yb2S3 (in mol.%) codoped chalcohalide glass, the quantum yield equals 10.8%. Although this efficiency is still low, this result will open a new route to realize the efficient spectral modification of the solar spectrum.

Epithelial-mesenchymal transition contributes to SWCNT-induced pulmonary fibrosis.

Previous studies suggest that single-walled carbon nanotube (SWCNT) exposure causes pulmonary fibrosis. We investigated the contribution of epithelial-mesenchymal transition (EMT) during SWCNT-induced pulmonary fibrosis. C57BL6 female mice were intratracheally instilled with SWCNT at 80 µg/mouse for up to 56 days. SWCNT exposure caused pulmonary epithelial and mesenchymal injury, followed by granulomatous and fibrotic changes. Immunofluorescence staining demonstrated the increasing occurrence of epithelial-derived fibroblasts up to 42 days post-exposure. Flow cytometry analysis revealed that 42.60% of N-cadherin (N-cad)-positive fibroblasts were derived from pulmonary epithelial cells, and, in separate experiments, 30.68% of SPC positive cells were stained for N-cad at 42 days. These epithelial-derived fibroblasts were functional in collagen production. With the progression of fibrosis, there were increases in the number of hyperplastic epithelial cells stained positively for TGF-ß/p-Smad2 or ß-catenin. Therefore, EMT contributes significantly to fibroblast expansion. Aberrant activations of TGF-ß/p-Smad2 and ß-catenin are postulated to induce EMT during SWCNT-induced pathogenic fibrosis.

Elastases from inflammatory and dendritic cells mediate ultrafine carbon black induced acute lung destruction in mice.

CONTEXT: Exposure to ultrafine particles (<100 nm in diameter) is postulated to cause chronic obstructive pulmonary disease (COPD). However, the mechanism remains to be elucidated. OBJECTIVE: We aimed to evaluate whether ultrafine particle exposure causes the infiltration of inflammatory and dendritic cells (DCs) with increased elastase activity, contributing to lung parenchymal destruction. MATERIALS AND METHODS: C57BL/6 male mice were intratracheally instilled with 300 µg ultrafine carbon black (ufCB; 14 nm in diameter), and sacrificed at 1, 3, 7 and 14 d post-exposure. Differential cell counts, elastase activities, and desmosine and hydroxyproline in bronchoalveolar (BAL) fluid were determined. Immunofluorescent staining and flow cytometry analysis determined the cell origin of macrophage metalloelastase (MMP-12). Anti-neutrophil antibody was applied to assess the contribution of elastase in ufCB induced lung destruction. RESULTS: ufCB exposure led to significant increases in neutrophils, mononuclear cells and total proteins in BAL fluid. Desmosine and hydroxyproline were significantly increased in the ufCB group. Elastase activities were found to be significantly elevated, with both neutrophil elastase and MMP-12 peaking at 3 d post-exposure. Flow cytometry analysis demonstrated that pulmonary infiltrations of MMP-12 positive DCs, including Langerhans cells-derived DCs, occurred at 3 d and 7 d, while macrophage infiltration was obvious starting at 1 d. Anti-neutrophil antibody significantly reduced neutrophil elastase activity and prevented the increases in BAL desmosine and hydroxyproline following ufCB exposure. CONCLUSION: For the first time we demonstrate the infiltration of Langerhans and myeloid dendritic cells, and show that elastase production contributes to pulmonary destruction following exposure to ultrafine particles.

[Mid-infrared emission properties of Ho3+/Tm(3+)-codoped Ge-Ga-S-CsI glasses].

A serial of chalcogenide glasses based on 78GeS2-12Ga2S3-10CsI (in molar%) system doped with the different radios of Ho3+/Tm3+ ions were synthesized by melt-quenching method. Their absorption spectra and mid-infrared fluorescence under 808 nm laser excitation were measured. According to Judd-Ofelt theory, the intensity parameters omega(i) (i = 2, 4, 6), spontaneous transition probabilities A(rad) and radiative lifetomes tau(r) for Ho3+ ion were calculated. Absorption cross-sections sigma(a), emission cross-sections sigma(e) and gain coefficient G(lambda) corresponding to the emission of Ho3+ ions at 2.0 microm were obtained. By changing the Tm3+ concentration, the energy transfer regime of Tm3+ and Ho3+ ions under 808 nm excitation was investigated. The results show that Ho3+/Tm(3+)-codoped Ge-Ga-S-CsI glasses would be a potential material for 2.0 microm emission.

[Energy transfer and mid-infrared luminescence properties of Tm3+ /Dy3+ codoped chalcohalide glasses].

A series of chalcohalide glasses based on the composition 0.9 (Ge25 Ga5 S70)-0.1CsI doped with the different Tm3+ / Dy3+ ions ratio were synthesized by melt-quenching technique. The absorption spectra, and mid-infrared fluorescence of different glass samples under 800 nm laser excitation were measured. The results prove that, Tm3+ is an efficient sensitizer, which can enhance the Dy3+ : 2.9 microm fluorescence intensity significantly. A decrease in the intensity of 1.8 microm fluorescence and lifetimes of the Tm3+ : (3)F4 level occurred with increasing the concentration of Dy3+ ions from 0 to 1 Wt% where Tm3+ concentration was fixed to 0.5 Wt%. Also a wide spectral overlap between Tm+ : 1.8 microm emission and the absorption of Dy3+ : 6 H(15/2) --> (6)H(11/2) showed that the effective energy transfer between the two rare-earth ions was mainly attributed to the resonance energy from Tm3+: (3)F4 to Dy(3)+ : (6)H(11/2) level.

[Mid-infrared emission and multiphonon relaxation in Tm3+-doped Ge-Ga-Se glasses].

A series of chalcogenide glasses based on the composition Ge30 Ga5 Se65 (at. %) doped with the different Tm3+ ions were synthesized by melt-quenching technique. The refractive indexes, Raman spectra, absorption spectra, near-and mid-infrared fluorescence, and lifetimes of glass samples under 800 nm laser excitation were measured. The intensity parameters omega(i) (i = 2, 4, 6), transition probabilities, branching ratios and radiative lifetimes have been predicted for Tm3+ ions in samples by using the Judd-Ofelt theory. The near-infrared emission spectra at 1.23, 1.48 and 1.8 microm were observed and their quantum efficiencies were evaluated respectively in glass doped with 1 Wt% Tm(3+)-ions under 800 nm excitation. The mid-infrared fluorescence spectra were investigated with the different Tm3+ ion concentration under 800 nm excitation. The multiphonon relaxation rate of Tm3+ : 3 H5 --> 3F4 by the measured and calculated lifetimes, and the relative parameters of W(0) and a in Ge30 Ga5 Se65 glass were evaluated. Results show that the multiphonon relaxation rates were significantly lower than other glasses due to the lower maximum phonon energy, so the selenide glasses are promising as host materials for doping by rare earth ions and for preparation of mid-infrared optical elements.

[Assessment of cerebral oxygen saturation using near infrared spectroscopy under driver fatigue state].

The objective of the present study is to assess the cerebral saturation under driver fatigue based on the near infrared spectroscopy (NIRS) signals. Twenty healthy male subjects were randomly divided into two groups: A-group (study group) and B-group (control group). All subjects were required to be well rested before the experiment. In A-group the subjects were required to perform the simulated driving task for 3 hours. Cerebral oxygenation signal was monitored for 20 minutes prior to and after the prescribed task period from the left frontal lobe. The results show that cerebral oxygen saturation was found to be significantly lower following 3-hour driving in the task group compared to that in the control group (F = 15.92, p < 0.001). Also a significant difference in selective reaction time was observed between the task group and control group during the post task period (p = 0.021). These findings showed that the cerebral blood oxygen saturation was closely related to the driver fatigue. The decline of the cerebral oxygen saturation might indicate a reduced cerebral oxygen delivery. This suggests that NIRS could provide a non-invasive method to detect driver fatigue.

[Influence of erbium ion concentration on Judd-Ofelt parameters of Er3+ -doped tellurite glass].

Er3+ -doped tellurite glasses with four different concentrations were fabricated, and the oscillator strength of Er3+ in the tellurite glasses were calculated through the absorption spectra of the glasses. The Judd-Ofelt intensity parameter omega i, spontaneous transition probability A, fluorescence branching ratio beta, and radiative lifetime tau rad of Er3+ were calculated on the basis of Judd-Ofelt theory, and the effect of the erbium ion concentration on the above optical parameters was also discussed. The fluorescence spectra of Er3+: (4)I(13/2)--> (4)I(15/2) transition and the lifetime of Er3+: (4)I(13/2) level of the samples were measured. The stimulated emission cross-section of (4)I(13/2)--> (4)I(15/2) transition of the samples was finally calculated by using McCumber theory. The results show that with the increase in the Er3+ concentration, the oscillator strength and spontaneous transition probability A of Er3+ increase, while the fluorescence branching ratio beta of Er3+ shows little difference. The stimulated emission cross-section of Er3+: (4)I(13/2)--> (4)I(15/2) transition of the samples changes slightly with the increase in the Er3+ concentration. All the fluorescence effective line widths for the four different Er3+ concentration samples are nearly 50 nm.