Growth, spectroscopy and SESAM mode-locking of a "mixed" Yb:Ca(Gd,Y)AlO4 disordered crystal.

We present the growth, spectroscopy, continuous-wave (CW) and passively mode-locked (ML) operation of a novel "mixed" tetragonal calcium rare-earth aluminate crystal, Yb3+:Ca(Gd,Y)AlO4. The absorption, stimulated-emission, and gain cross-sections are derived for π and σ polarizations. The laser performance of a c-cut Yb:Ca(Gd,Y)AlO4 crystal is studied using a spatially single-mode, 976-nm fiber-coupled laser diode as a pump source. A maximum output power of 347 mW is obtained in the CW regime with a slope efficiency of 48.9%. The emission wavelength is continuously tunable across 90 nm (1010 - 1100 nm) using a quartz-based Lyot filter. With a commercial SEmiconductor Saturable Absorber Mirror to initiate and maintain ML operation, soliton pulses as short as 35 fs are generated at 1059.8 nm with an average output power of 51 mW at ∼65.95 MHz. The average output power can be scaled to 105 mW for slightly longer pulses of 42 fs at 1063.5 nm.

Continuous-wave and SESAM mode-locked operation of a Yb:YSr3(PO4)3 laser.

We report on the continuous-wave (CW) and, for what we believe to be the first time, passively mode-locked (ML) laser operation of an Yb3+-doped YSr3(PO4)3 crystal. Utilizing a 976-nm spatially single-mode, fiber-coupled laser diode as pump source, the Yb:YSr3(PO4)3 laser delivers a maximum CW output power of 333 mW at 1045.8 nm with an optical efficiency of 55.7% and a slope efficiency of 60.9%. Employing a quartz-based Lyot filter, an impressive wavelength tuning range of 97 nm at the zero level was achieved in the CW regime, spanning from 1007 nm to 1104 nm. In the ML regime, incorporating a commercially available semiconductor saturable absorber mirror (SESAM) to initiate and maintain soliton-like pulse shaping, the Yb:YSr3(PO4)3 laser generated pulses as short as 61 fs at 1062.7 nm, with an average output power of 38 mW at a repetition rate of ∼66.7 MHz.

[Comparative analysis for the cytotoxicity and genotoxicity of multi-walled carbon nanotubes with different lengths and surface modifications in A549 cells].

OBJECTIVE: To compare the cytotoxicity and DNA strand breakage induced by multi-walled carbon nanotubes (MWCNTs) with different lengths and different surface modifications in human alveolar type II cells (A549 cells). METHODS: Two different lengths (5-15 µm, 350-700 nm) of MWCNTs and three different kinds of surface modified MWCNTs (COOH-MWCNTs, NH2-MWCNTs, and Tau-MWCNTs) were used in the experiments. The short MWCNTs were used as pristine MWCNTs to compare with the 3 surface modified MWCNTs. The cytotoxicity was determined by cell counting kit-8 (CCK-8) assay at the concentrations of 2, 8, and 32 mg/L at hours 12, 24, 36, and 48 respectively. Single cell gel electrophoresis (SCGE) assay was performed to evaluate DNA strand breakage in A549 cells after 24 h treatment of 8 mg/L of each tested material. RESULTS: Long multi-walled carbon nanotubes (Long-MWCNTs) and short multi-walled carbon nanotubes (Short-MWCNTs) showed a dose-dependent cytotoxicity within the exposure time 12-48 h. Especially, Long-MWCNTs showed greater cytotoxicity than Short-MWCNTs from 24 to 48 h at the same concentration. The relative cell viability of the 3 surface modified MWCNTs was higher than that of the pristine MWCNTs at h 12 at the concentration of 32 mg/L [COOH-MWCNTs (86.55±1.80)%, NH2-MWCNTs (84.67±1.32)%, Tau-MWCNTs (80.15±3.53)% and Pristine-MWCNTs (71.44±5.58)%], at h 24 at the concentration of 8 mg/L [COOH-MWCNTs (96.74±1.00)%, NH2-MWCNTs (96.74±3.35)%, Tau-MWCNTs (106.39±3.83)% and Pristine-MWCNTs (91.02±2.53)%], at h 24 at the concentration of 32 mg/L [COOH-MWCNTs (80.88±2.67)%, NH2-MWCNTs (82.90±3.25)%, Tau-MWCNTs (82.55±3.32)% and Pristine-MWCNTs (76.08±4.27)%] and at h 36 at the concentration of 8 mg/L [COOH-MWCNTs (96.87±1.05)%, NH2-MWCNTs (96.66±4.76)%, Tau-MWCNTs (100.23± 2.84)% and Pristine-MWCNTs (89.61±3.78)%], and the differences were statistically significant (P<0.05). Compared with the Pristine-MWCNTs, the relative cell viability of the 3 surface modified MWCNTs didn't demonstrate a statistically significant difference (P>0.05) at other observation time and exposure concentrations. The DNA strand breakage of the 3 surface modified MWCNTs: the Olive tail moment of COOH-MWCNTs was 1.56±0.22, the Olive tail moment of NH2-MWCNTs 2.25±1.62 and the Olive tail moment of Tau-MWCNTs 2.23±0.94; the tail DNA% of COOH-MWCNTs was (3.96± 0.60)%, the tail DNA% of NH2-MWCNTs (6.16±4.68)% and the tail DNA% of Tau-MWCNTs (6.05±2.31)%, which were lower than that of the pristine MWCNTs (P<0.05), whose Olive tail moment was 3.00±0.64 and tail DNA% (8.23±2.27)%. Moreover, the COOH-MWCNTs induced the lowest DNA damage among the three modified MWCNTs. CONCLUSION: Long-MWCNTs compared with Short-MWCNTs demonstrated a greater cytotoxicity and lower DNA strand breakage damage. The surface modifications of MWCNTs can reduce the cytotoxicity and DNA strand breakage in A549 cells.

[Effect of titanium dioxide nanoparticles on hemogram in rats with gastric ulcer].

OBJECTIVE: To explore the effect of titanium dioxide (TiO2) nanoparticles on hemogram in rats with gastric ulcer. METHODS: Physicochemical properties of TiO2 nanoparticles were characterized. Twenty-four clear class SD male rats, aging 8 week-old, were randomly divided into 4 groups, 6 rats for each group. 20% acetic acid were injected into the rats' stomach on the border of gastric body and pyloric antrum, and hereby established the gastric ulcer model. The rats in 4 groups were exposed to TiO2 nanoparticles through intragastric administration at 0, 10, 50 and 200 mg/kg body weight respectively for 30 days. Afterwards, the rats were conducted blood routine test and blood coagulation test for analysis. RESULTS: TiO2 nanoparticles were anatase crystals, closely spherical shape, whose average grain diameter was (75 ± 15) nm. The levels of white blood cell (WBC) count ((8.48 ± 3.28)×109/L), lymphocyte (LYM) ((6.85 ± 2.53)×109/L), monocyte (MOD) ((0.27 ± 0.12)×109/L), granulocyte (GRN) ((1.37 ± 0.86)×109/L), red blood cell (RBC) ((8.20 ± 0.49)×109/L) and hematocrit (HCT) ((45.3 ± 1.4)%) in the 200 mg/kg dose group were significantly higher than those in the control group ((2.63 ± 0.34)×109/L, (2.25 ± 0.26)×109/L, (0.05 ± 0.06)×109/L, (0.33 ± 0.26)× 109/L, (4.87 ± 2.37)×109/L and (27.2 ± 13.3)%, respectively; t values were -3.449, -3.825, -3.554, -3.097, -2.972 and -2.936 respectively, P values all < 0.05). The levels of WBC ((6.88 ± 3.06)×109/L), MOD ((0.20 ± 0.07)×109/L), RBC ((7.79 ± 0.48)×109/L) and HCT ((42.7 ± 2.8)%) in 50 mg/kg dose group were also statistically higher than those in the control group (t values were -2.507, -2.367, -2.605 and -2.511 respectively, all P values < 0.05). There was no statistically difference found in other blood routine index and coagulation index between the three experimental groups and control group. CONCLUSION: The long term intake of TiO2 nanoparticles caused a statistically increase in the amount of WBC and RBC in rats with gastric ulcer; however, there was no obvious changes found in blood platelet and coagulation index.

[The cytotoxicity and expression changes of endoplasmic reticulum related genes induced by MWCNTs with different surface modifications].

OBJECTIVE: To compare the cytotoxicity of RAW264.7 cells induced by two types of multi-walled carbon nanotubes (MWCNTs) with different surface modifications (MWCNTs modified by taurine and MWCNTs treated by acid), and explore the role of endoplasmic reticulum (ER) in MWCNTs-induced apoptosis. METHODS: RAW264.7 cells were exposed to tau-MWCNTs or c-MWCNTs, of which the diameters and impurity contents were the same, at the dose of 0, 1.56, 3.12, 6.25, 12.50, 25.00 µg/cm(2) for 3, 6, 12 and 24 h, respectively. Then the cytotoxicity of MWCNTs was determined by WST-1 assay, and the percentages of apoptosis were analyzed via flow cytometry with AnnexinV-FITC/PI label. Real-time PCR was used to detect mRNA expression levels of CRT, GRP78 and CHOP genes which were related to ER calcium regulation, stress and apoptosis. RESULTS: Compared with the c-MWCNTs groups, the cytotoxicity of tau-MWCNTs was lower at the same dose and treatment time. Both the two types of MWCNTs could induce cytotoxicity apparently and statistically, when the cells were treated for only 3 h at the doses of more than 12.50 µg/cm(2) or treated for more than 12 h at the lower dose of 3.12 µg/cm(2) (P<0.05). The results of flow cytometry showed that the two MWCNTs could induce apoptosis of RAW264.7 cells in the dose- and time-dependently manner. The apoptosis rate of the cells treated for 24 h was higher than that for 12 h. And at each dose, the apoptosis rate induced by c-MWCNTs was also higher than that of the water soluble tau-MWCNTs within our study design. However, in this study, the mRNA expression levels of CRT, GRP78 and CHOP mRNA treated with both types of MWCNTs did not show any significant differences compared with the control groups. CONCLUSION: The cytotoxicity of tau-MWCNTs was much lower than that of c-MWCNTs. Unfortunately, we found the expression of genes related to ER had little effects on the apoptosis of RAW264.7 treated with MWCNTs, indicating that the ER pathway might not be the mechanism of MWCNTs-induced apoptosis.

[Two types of MWNTs with different surface modifications induce differential expression of proteins in RAW264.7 cells].

OBJECTIVE: To compare the different expression of protein in RAW264.7 macrophage cells induced by two types of MWNTs (multi-walled carbon nanotubes) with different surface modifications (acid-treated MWNTs and tau-MWNTs modified by taurine). METHODS: Treating cells with both types of MWNTs in 20 mg/L and 24 h, with a blank-control group set. Cells are lysed by using urea and by ultrasonicating in ice bath, then total proteins of cells are extracted. Using two-dimensional gel electrophoresis to separate total proteins of cells, searching for the differential expressed protein spots on the images of the gels with silver staining. Identifying the differentially expressed proteins via mass spectrometry, and studying the mechanism of effects on cells imposed by two types of MWNTs at protein level. RESULTS: There are 13 spots of protein with notably differential expression among three treated groups (including blank controls). Their functions involve apoptosis-related, calcium-binding, cell-cycle related, DNA synthesis, folding of proteins, and energy metabolism, etc. The results are consistent with our previous studies about the cytotoxicity of Both types of MWNTs including induction of apoptosis and mitochodira damage. CONCLUSION: Both two types of MWNTs could induce alteration of protein expression in RAW264.7 cells. With different surface modifications, they imposed different effects. High throughout proteomics could be applied in toxicity assessment and mechanism investigation about carbon nanotubes.