Energy transfer mechanisms between Er³⁺ and Pr³⁺ in Er³⁺/Pr³⁺ codoped germinate glass are investigated in detail. Under 980 nm LD pumping, 2.7 μm fluorescence intensity enhanced greatly. Meanwhile, 1.5 μm lifetime and fluorescence were suppressed deeply due to the efficient energy transfer from Er³⁺:⁴I_13/2 to Pr³⁺:³F_3,4, which depopulates the ⁴I_13/2 level and promotes the 2.7 μm transition effectively. The obvious change in J-O parameters indicates that Pr³⁺ influences the local environment of Er³⁺ significantly. The increased spontaneous radiative probability in Er³⁺/Pr³⁺ glass is further evidence for enhanced ⁴I_11/2 → ⁴I_13/2 transition. The Er³⁺:⁴I_11/2→Pr³⁺:¹G₄ process is harmful to the population accumulation on ⁴I_11/2 level, which inhibits the 2.7 μm emission. The microscopic energy transfer coefficient of Er³⁺:⁴I_13/2→Pr³⁺:³F_3,4 is 42.25 × 10⁻⁴⁰ cm⁶/s, which is 11.5 times larger than that of Er³⁺:⁴I_11/2→Pr³⁺:¹G₄. Both processes prefer to be non-phonon assisted, which is the main reason why Pr³⁺ is so efficient in Er³⁺:2.7 μm emission. Full article

In this paper, we report the formation of hierarchically self-assembled nanofiber films from amylose-grafted sodium carboxymethyl celluloses (NaCMCs) that were synthesized by a chemoenzymatic approach. First, maltooligosaccharide primer-grafted NaCMCs were prepared by a chemical reaction using two kinds of NaCMCs with different degrees of polymerization (DPs) from Avicel and cotton sources. Then, phosphorylase-catalyzed enzymatic polymerization of α-d-glucose 1-phosphate from the nonreducing ends of the primer chains on the products was conducted to produce the prescribed amylose-grafted NaCMCs. The films were obtained by drying aqueous alkaline solutions of the amylose-grafted NaCMCs. The scanning electron microscopy (SEM) image of the film fabricated from the material with the higher DP from the cotton source showed a clear, self-assembled, highly condensed tangle of nanofibers. The SEM image of the material with the lower DP from the Avicel source, on the other hand, showed an unclear nanofiber morphology. These results indicate that the DPs of the main chains in the materials strongly affected the hierarchically self-assembled nanofiber formation. The SEM images of the films after washing out the alkali, furthermore, showed that the fibers partially merged with each other at the interfacial area owing to the double helix formation between the amylose-grafted chains. The mechanical properties of the films under tensile mode also depended on the self-assembled morphologies of the amylose-grafted NaCMCs from the different sources. Full article

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. Full article

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. Full article

In this review paper some recent advances on optical fiber sensors are reported. In particular, fiber Bragg grating (FBG), long period gratings (LPGs), evanescent field and hollow core optical fiber sensors are mentioned. Examples of recent optical fiber sensors for the measurement of strain, temperature, displacement, air flow, pressure, liquid-level, magnetic field, and the determination of methadone, hydrocarbons, ethanol, and sucrose are briefly described. Full article

In the present review article immune responses induced by carbon nanotubes (CNTs) are addressed. As inhalation is considered to be the primary entry route, and concern has been raised by similar high aspect ratio materials, the main focus lies on immune responses upon pulmonary exposure. Inflammation-related findings from both in vivo studies and in vitro models are reviewed, and the major responsible characteristics, which may drive CNT-induced inflammation in the lung, are discussed. In a second part, responses upon intentional administration of CNTs via subcutaneous and intravenous application are addressed, including their potential benefits and drawbacks for immunotherapy. Finally, the gastrointestinal tract as an alternative exposure route is briefly discussed. While there are many studies identifying numerous other factors involved in CNT-driven toxicity, e.g., cytotoxicity, oxidative stress, and genotoxicity, the focus of this review was kept solely on CNT-induced inflammation. Overall the literature has shown that CNTs are able to induce inflammation, which in some cases was a particularly robust response coinciding with the development of pro-fibrotic conditions. In the majority of cases the greatest inflammatory responses were associated with CNTs of considerable length and a high aspect ratio, accompanied by other factors like dispersion and sample purity. Full article