Fibers2014, 2(2), 150-157; doi:10.3390/fib2020150 - published online 16 April 2014 Show/Hide Abstract
Abstract: In the article a novel construction of a side-detecting luminescent optical fiber for an UV sensor application has been presented. In the fiber, structure phosphate glass doped with 0.5 mol% Tb3+ ions was used as a UV sensitive core/ribbon. The luminescence spectrum of glass and the optical fiber was measured under UV excitation using a deuterium lamp. It was found that large energy gap between upper (metastable) and lower (ground) levels of terbium ions incorporated in phosphate matrix leads to the effective emission at wavelengths of 489, 543, 586 and 621 nm, which correspond to 5D4 → 7FJ, (J = 3, 4, 5, 6) transitions respectively. Phosphate glass doped with optimal (the strongest VIS emission) concentration of Tb3+ (0.5 mol%) was used as the active core/ribbon in the construction of UV side-detecting optical fiber.
Fibers2014, 2(2), 142-149; doi:10.3390/fib2020142 - published online 14 April 2014 Show/Hide Abstract
Abstract: An ultra-high sensitive strain sensor is proposed. The sensing head, based on the post-processing of a fiber Bragg grating, is used to perform passive and active strain measurements. Both wavelength and full width half maximum dependences with the applied strain are studied for the passive sensor, where maximum sensitivities of 104.1 pm/µε and 61.6 pm/µε are respectively obtained. When combining the high performance of this sensor with a ring laser cavity configuration, the Bragg grating will act as a filter and high resolution measurements can be performed. With the proposed sensor, a resolution of 700 nε is achieved.
Fibers2014, 2(2), 128-141; doi:10.3390/fib2020128 - published online 10 April 2014 Show/Hide Abstract
Abstract: To reduce particulate matter (PM) in diesel exhaust gas, a diesel particulate filter (DPF) has been developed. The thermal durability of existing platinum catalyst-supported DPFs is inadequate. We are focusing on a non-catalytic after-treatment of silicon carbide (SiC) fibers with highly thermal durability. In this study, we simulated the processes of soot deposition and oxidation. Results show that even in exhaust gas without soot, a complex flow pattern is observed. The porosity of the filter is not constant along the flow direction, and the pressure gradient varies. The friction factor is slightly larger than the predicted value by the empirical equation in uniform porous media flow. Since the soot deposition occurs inside the filter, the depth filtration by SiC fibers was confirmed. In addition, the effects of filter temperature and oxygen concentration are clearly revealed. That is, comparing the oxidation at 700 °C, the deposited soot amount at 1200 and 1400 °C is decreased by 60% and 92%, respectively. Raising the oxygen concentration from 10% to 20% increases the oxidation efficiency from 42% to 64%. Although more work is needed over a wide range of operating conditions, a combination of these two parameters is important to achieve the non-catalytic exhaust after-treatment.
Fibers2014, 2(2), 108-127; doi:10.3390/fib2020108 - published online 28 March 2014 Show/Hide Abstract
Abstract: Carbon nanotube (CNT)/polymer nanocomposites have superior properties compared to the neat polymer matrix. They now are widely used in industry, but questions have been raised about the risks of such materials since CNTs can be toxic when inhaled. For a risk assessment of CNT nanocomposites, it is crucial to know whether CNTs from nanocomposites can be released into the environment or if they remain embedded in the matrix. This review article summarizes the studies that investigated the release of CNTs from nanocomposites during the service life. Three scenarios are reviewed, the release of particles due to mechanical impact, the release due to weathering processes, and the release due to fire. A release during composite production and disposal is not incorporated.
Fibers2014, 2(1), 92-107; doi:10.3390/fib2010092 - published online 21 March 2014 Show/Hide Abstract
Abstract: This paper is dedicated to the lifetime prediction of Type I Fiber Bragg gratings (FBG) and to problems that happen when stabilization (also called passivation) conditions or the industrial conditioning procedure depart from ageing ones (e.g., presence of hydrogen during the passivation process). For the first time, a reliable procedure to certify the predicted lifetime based on a “restricted” master curve built on real components (i.e., passivated FBG) is presented. It is worth noting that both procedures (master curve built on non-passivated or on passivated components) are based on the same model (demarcation energy approximation and the existence of a master curve) fed with ageing data (reflectivity decay vs. time and temperature). If the Master Curve (MC) build on passivated components can be derived from the original one, we can certify the lifetime prediction in a reliable manner.
Fibers2014, 2(1), 75-91; doi:10.3390/fib2010075 - published online 25 February 2014 Show/Hide Abstract
Abstract: This work reports on the implementation of electrospinning (ES) as a facile route to encapsulate nano-engineered materials in a polystyrene (PS) matrix. We applied ES to co-encapsulate two kinds of nanoparticles, i.e., upconversion nanophosphors (UCNPs) and superparamagnetic iron oxide nanoparticles (SPIONs), in polystyrene (PS)-based micro- and nano-fibers (PSFs). This approach made it possible to integrate near-infrared (NIR) light-sensitive 500-nm β-NaYF4:Yb, Er UCNPs with 10-nm γ-Fe2O3 SPIONs in PS fibers. During the ES process, PSFs were additionally loaded with a well-established singlet oxygen (1∆g) photosensitizer, rose bengal (RB). The thus obtained PSFs revealed the promising features of prospective multi-functional magnetic photoluminescent photocatalytic nano-constructs.