Femtosecond Laser Micro/nano Machining on Metallic and Semiconductor Materials

Formation of ripples or laser induced periodic surface structures (LIPSS) on semiconductor material like Silicon (Si) and on metals like Aluminum (Al) and Copper (Cu) and fabrication Silver (Ag) nanostructures in polymer matrix by femtosecond (fs) laser direct writing are reported in this paper. Laser irradiation was performed at normal incidence in air using linearly polarized Ti:Sapphire fs laser pulses of ~ 110 fs pulse duration and ~ 800 nm wavelength. Field emission scanning electron microscopy (FESEM) is utilized for imaging surface morphologies of laser written structures, revealing that surface morphology depends on various material processing parameters like laser fluence, polarization, material properties and number of applied pulses. Formation of polymer capped Ag nanoparticles inside the laser written microstructures is confirmed by the appearance of surface plasmon absorption band at 448 nm in the UV-Vis extinction spectrum. Nanoparticles formed were spherical in shape with an average particle size less than 20 nm. This technique is efficient, universal, cost-effective, and environmental friendly, which has potential applications in the fabrication of micro/nanostructures on variety of materials for microelectromechanical systems, nanoelectronics and nanophotonics

Femtosecond Laser Micro/nano Machining on Metallic and Semiconductor Materials

Formation of ripples or laser induced periodic surface structures (LIPSS) on semiconductor material like Silicon (Si) and on metals like Aluminum (Al) and Copper (Cu) and fabrication Silver (Ag) nanostructures in polymer matrix by femtosecond (fs) laser direct writing are reported in this paper. Laser irradiation was performed at normal incidence in air using linearly polarized Ti:Sapphire fs laser pulses of ~ 110 fs pulse duration and ~ 800 nm wavelength. Field emission scanning electron microscopy (FESEM) is utilized for imaging surface morphologies of laser written structures, revealing that surface morphology depends on various material processing parameters like laser fluence, polarization, material properties and number of applied pulses. Formation of polymer capped Ag nanoparticles inside the laser written microstructures is confirmed by the appearance of surface plasmon absorption band at 448 nm in the UV-Vis extinction spectrum. Nanoparticles formed were spherical in shape with an average particle size less than 20 nm. This technique is efficient, universal, cost-effective, and environmental friendly, which has potential applications in the fabrication of micro/nanostructures on variety of materials for microelectromechanical systems, nanoelectronics and nanophotonics

Structural, thermal, optical properties and simulation of white light of titanium-tungstate-tellurite glasses doped with dysprosium

Structural, thermal, optical properties and simulation of white light of Dy3+-doped tellurite glasses of composition TTWD: (75 - x)TeO2 - 10TiO(2) - 15WO(3) - xDy(2)O(3) (x = 0, 0.1, 0.5, 1.0 and 2.0 mot%) were investigated. Raman spectra revealed that the glass contains TeO4, TeO3, WO4 and WO6 units. Differential scanning calorimetry (DSC) measurements were carried out to measure the glass transition temperature of all the glasses. From the optical absorption spectra, luminescence spectra and using the Judd-Ofelt (JO) analysis, we estimated the radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes. The decay curves at lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (<= 0.5 mol%) due to energy transfer processes. The effective lifetime for the F-4(9/2) level decreases with increase in Dy2O3 concentration for the glasses under investigation. The non-exponential decay curves could fit well to the Inokuti-Hirayama (IH) model with S = 6, indicating that the nature of interaction responsible for energy transfer is of dipole-dipole type. Simulation of white light is examined with varying concentration and the results indicate that these glasses are suitable for white light emitting diode applications. (C) 2013 Elsevier Ltd. All rights reserved

Correction: Lack of Effect of Oral Sulforaphane Administration on Nrf2 Expression in COPD: A Randomized, Double-Blind, Placebo Controlled Trial.

[This corrects the article DOI: 10.1371/journal.pone.0163716.]

Lack of Effect of Oral Sulforaphane Administration on Nrf2 Expression in COPD: A Randomized, Double-Blind, Placebo Controlled Trial.

COPD patients have high pulmonary and systemic oxidative stress that correlates with severity of disease. Sulforaphane has been shown to induce expression of antioxidant genes via activation of a transcription factor, nuclear factor erythroid-2 related factor 2 (Nrf2).This parallel, placebo-controlled, phase 2, randomized trial was conducted at three US academic medical centers. Patients who met GOLD criteria for COPD and were able to tolerate bronchoscopies were randomly assigned (1:1:1) to receive placebo, 25 μmoles, or 150 μmoles sulforaphane daily by mouth for four weeks. The primary outcomes were changes in Nrf2 target gene expression (NQ01, HO1, AKR1C1 and AKR1C3) in alveolar macrophages and bronchial epithelial cells. Secondary outcomes included measures of oxidative stress and airway inflammation, and pulmonary function tests.Between July 2011 and May 2013, 89 patients were enrolled and randomized. Sulforaphane was absorbed in the patients as evident from their plasma metabolite levels. Changes in Nrf2 target gene expression relative to baseline ranged from 0.79 to 1.45 and there was no consistent pattern among the three groups; the changes were not statistically significantly different from baseline. Changes in measures of inflammation and pulmonary function tests were not different among the groups. Sulforaphane was well tolerated at both dose levels.Sulforaphane administered for four weeks at doses of 25 μmoles and 150 μmoles to patients with COPD did not stimulate the expression of Nrf2 target genes or have an effect on levels of other anti-oxidants or markers of inflammation.Clinicaltrials.gov: NCT01335971

Fold-change^* in inflammatory marker concentrations by treatment group.

<p>Fold-change^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163716#t004fn002" target="_blank">*</a>} in inflammatory marker concentrations by treatment group.</p

Baseline measures of antioxidants and markers of inflammation by treatment group.

<p>Baseline measures of antioxidants and markers of inflammation by treatment group.</p