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Presents a study that demonstrated the influence of plasma shielding on the coupling of laser energy to a target surface during picosecond pulsed laser-material interactions. Information on hellium and argon gas atmosphere; Use of inductively coupled plasma-atomic emission spectrometer; Discussion on the mechanisms of shock waves, multiphoton ionization and plasma shielding.

OBJECTIVE: Fragility fracture is one of the common complications of osteoporosis. Elevated oxidative stress-induced apoptosis is thought to be one of the unfavorable factors to osteoblastic dysfunction, which increased the risk of bone fracture. However, the molecular mechanisms for oxidative stress-induced osteoblast cells apoptosis still needs to be elucidated. This study aims to investigate the protective function of miR-214 in H2O2-induced apoptosis of MC3T3-E1 osteoblasts. cMATERIALS AND METHODS: MC3T3-E1 cells were treated with 400 μM H2O2. Flow cytometry was adopted to detect the apoptosis rate; malondialdehyde (MDA) and glutathione peroxidase (Gpx) levels were used to determine the reactive oxygen species (ROS) level. Reverse transcription- polymerase chain reaction (RT-PCR) was employed to test the expression level of miR-214 and ATF4. After transfected MC3T3-E1 cells with miR-214 mimics and inhibitor, RT-PCR was used to detect activating transcription factor 4 (ATF4) expression level. RESULTS: H2O2 treatment increased ROS induced intracellular oxidative injury. Flow cytometry showed that 400 μM H2O2 induced the apoptosis of MC3T3-E1 cells. Moreover, RT-PCR showed decreased expression level of MiR-214. Furthermore, the apoptosis induced by high ROS level was reversed by increased miR-214 expression level. The regulatory ability of MiR-214 to apoptosis is by regulating ATF4 expression. CONCLUSIONS: miR-214 plays a protective role in H2O2 induced MC3T3 osteoblasts apoptosis and its protective effect is proceeded by regulating ROS level and ATF4 expression level. [ABSTRACT FROM AUTHOR]

Submucosal tunneling endoscopic resection (STER) of subepithelial tumors (SETs) originating from the muscularis propria (MP) layer in the cardia is rarely performed due to the difficulty of creating a submucosal tunnel for resection. The aim of this study is to evaluate the feasibility of STER using methylene-blue guidance for SETs originating from the MP layer in the cardia. From January 2012 to December 2014, 56 patients with SETs originating from the MP layer in the cardia were treated with STER using methylene-blue guidance. The complete resection rate and adverse event rate were the main outcome measurements. Successful complete resection by STER was achieved in all 56 cases (100%). The median size of the tumor was 1.8 cm. Nine patients (15.3%) had adverse events including subcutaneous emphysema, pneumoperitoneum, pneumothorax, and pleural effusion. These nine patients recovered successfully after conservative treatment without endoscopic or surgical intervention. No residual or recurrent tumors were detected in any patient during the follow-up period (median, 25 months). The adverse event rate was significantly higher for tumors originating in the deeper MP layers (46.7%) than in the superficial MP layers (4.9%) (P < 0.05), differed significantly according to tumor size (5.4% for tumors < 2.0 cm vs. 36.8% for tumors ≥ 2.0 cm; P < 0.05), and also differed significantly in relation to the tumor growth pattern (4.1% for the intraluminal growth vs. 100% for the extraluminal growth; P < 0.001). STER using methylene-blue guidance appears to be a feasible method for removing SETs originating from the MP layer in the cardia. [ABSTRACT FROM AUTHOR]

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Femtosecond laser (Ti:sapphire, 100 fs pulse duration) ablation of silicon in air was compared with nanosecond laser (Nd:YAG, 3 ns pulse duration) ablation at ultraviolet wavelength (266 nm). Laser ablation efficiency was studied by measuring crater depth as a function of pulse number. For the same number of laser pulses, the fs-ablated crater was about two times deeper than the ns-crater. The temperature and electron number density of the laser-induced plasma were determined from spectroscopic measurements. The electron number density and temperature of fs-induced plasmas decreased faster than ns-induced plasmas due to different energy deposition mechanisms. Images of the laser-induced plasma were obtained with femtosecond time-resolved laser shadowgraph imaging. Plasma expansion in both the perpendicular and the lateral directions were compared. [ABSTRACT FROM AUTHOR]

Femtosecond and nanosecond lasers were compared for ablating brass alloys. All operating parameters from both lasers were equal except for the pulse duration. The ablated aerosol vapor was collected on silicon substrates for particle size measurements or sent into an inductively coupled plasma mass spectrometer. The diameters and size distribution of particulates were measured from scanning electron microscope (SEM) images of the collected ablated aerosol. SEM measurements showed that particles ablated using nanosecond pulses were single spherical entities ranging in diameter from several micrometers to several hundred nanometers. Primary particles ablated using femtosecond ablation were ∼100 nm in diameter but formed large agglomerates. ICPMS showed enhanced signal intensity and stability using femtosecond compared to nanosecond laser ablation. [ABSTRACT FROM AUTHOR]

Demonstrates a correlation between inductively coupled plasma and laser-induced plasma atomic spectral emission intensities for several homogeneous metallic oxide materials during laser ablation sampling over a range of power densities and incident laser beam spot sizes. Applications for higher melting temperature materials and moderate laser power density.

Superconducting Bi-Pb-Sr-Ca-Cu-O films doped with Sb have been fabricated on MgO single-crystal substrates without post-annealing, using pulsed excimer laser deposition. Deposition at 800 °C in 0.2 Torr oxygen environment from a target doped with Sb yielded as-deposited superconducting films with zero resistance at 70 K. X-ray diffraction data show the films are c-axis oriented 2212 phase material. Scanning electron micrographs indicate that doping with Sb enhances grain growth. These results demonstrate that Sb acts to stabilize the 2212 phase in the as-deposited films. [ABSTRACT FROM AUTHOR]

© 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The craters resulting from high-irradiance (1x10[sup 9]-1x10[sup 11] W/cm[sup 2]) single-pulse laser ablation of single-crystal silicon show a dramatic increase in volume at a threshold irradiance of 2.2x10[sup 10] W/CM[sup 2]. Time-resolved shadowgraph images show ejection of large particulates from the sample above this threshold irradiance, with a time delay ∼300 ns. A numerical model was used to estimate the thickness of a superheated layer near the critical state. Considering the transformation of liquid metal into liquid dielectric near the critical state (i.e., induced transparency), the calculated thickness of the superheated layer at a delay time of 200-300 ns agreed with the measured crater depths. This agreement suggests that induced transparency promotes the formation of a deep superheated layer, and explosive boiling within this layer leads to particulate ejection from the sample. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]