The photoluminescent-(PL)-properties of Pr³⁺-ions in indium-containing selenide-chalcogenide bulk-glasses are found to be superior when compared with gallium-containing analogues. We observe circa doubling of mid-infrared (MIR) PL intensity from 3.5 to 6 μm for bulk glasses, pumped at 1.55 μm wavelength, and an increased excited state lifetime at 4.7 μm. PL is reported in optically-clad fiber. Ga addition is well known to enhance RE³⁺ solubility and PL behavior, and is believed to form ([RE³⁺]-Se-[Ga(III)]) in the glasses. Indium has the same outer electronic-structure as gallium for solvating the RE-ions. Moreover, indium is heavier and promotes lower phonon energy locally around the RE-ion, thereby enhancing the RE-ion PL behavior, as observed here.

In the 21 st century, cancer has become a common and feared illness. Early detection is crucial for delivering the most effective treatment of patients, yet current diagnostic tests depend upon the skill of a consultant clinician and histologist for recognition of the cancerous cells. Therefore it is necessary to develop a medical diagnostic system which can analyze and image tissue instantly, removing the margin of human error and with the additional benefit of being minimally invasive. The molecular fingerprint of biological tissue lies within the mid-infrared (IR) region of the electromagnetic spectrum, 3-25µm wavelength. This can be used to determine a tissue spectral map and provide information about the absence or existence of disease, potentially in real-time and in vivo. However, current mid-IR broadband sources are not bright enough to achieve this. One alternative is to develop broadband, mid-IR, supercontinuum generation (SCG). Chalcogenide glass optical fibers have the potential to provide such mid-IR SC light. A popular chalcogenide glass fiber type is based on Ge-As-Se. For biomedical applications it is prudent to avoid the use of arsenic, on account of its toxicity. This paper investigates replacing arsenic with antimony, towards Ge-Sb-Se smallcore optical fibers for SCG. Physical properties of candidate glass pairs are investigated for glass stability via differential thermal analysis etc. and fiber optical loss measurements of associated fibers are assessed. These results are compared to analogous arsenic-containing chalcogenide glasses and optical fibers, and conclusions are drawn focusing on whether there is potential for antimony chalcogenide glass to be used for SCG for mid-infrared medical diagnostics.

Chalcogenide glasses are promising materials for mid-infrared (IR) fiber lasers (i.e. 3 -25 µm wavelength range). These glasses exhibit low phonon energies, together with large refractive indices, rare earth (RE-) ion solubility and sufficient mechanical and chemical robustness. Optical quality of the fiber is key. Gallium is known to promote RE-ion solubility in chalcogenide glasses, probably forming a [Pr (III) ] -Se -[Ga (III) ] associated type complex. Here, indium is investigated as an alternative additive to gallium in Pr 3+ -doped Ge-As-Se chalcogenide glasses. Indium has the same outer electronic structure as gallium. Moreover, indium has the advantage of being heavier than gallium, potentially promoting a lower phonon-energy, local environment of the RE-dopant. Zero to ~2000 ppmw (nominal parts per million by weight) Pr 3+ -doped Ge-As-In-Se bulk glasses are prepared using the melt-quench method. ~500 ppmw Pr 3+ -doped Ge-As-In-Se, optically-clad fiber is realized via fiber-drawing of extruded fiberoptic preforms. Fiber absorption and emission spectra are collected and compared with those of the bulk glasses.

BackgroundWe no longer consider Osteoarthritis (OA) as a degenerative disease, but rather as a multifactorial disorder in which low grade, chronic inflammation has a central role. In addition, evidence points to the presence of both peripheral and central nervous system sensitization as sources of pain in OA. Transcutaneous Vagus Nerve Stimulation (tVNS) has shown efficacy on pain, inflammation and central sensitization in other conditions such as fibromyalgia, pelvic pain, and headaches and therefore we hypothesized that tVNS could be an additional line of management for knee OA.ObjectivesTo assess the efficacy and safety of tVNS on nociceptive pain, central sensitization, neuropathic pain, depression, anxiety, and physical function in individuals with knee OA.MethodsAfferents of the auricular branch of vagus nerve were stimulated using an auricular electrode connected to a transcutaneous electrical nerve stimulation (TENS) device. We conducted 30 minutes session once a day for 3 days per week for 12 weeks. Sixty-eight patients with chronic knee OA were allocated randomly into active and sham group (34 patients in each group). The outcome measures included visual analogue scale (VAS), pressure pain threshold (PPT), PainDETECT and Douleur Neuropathique 4 (DN4) questionnaires, hospital anxiety and depression scale (HADS), and knee injury and osteoarthritis outcome score (KOOS). These outcome measures were assessed at baseline, at the end of the stimulation period then after 4 weeks later.ResultsThere was a significant improvement in VAS for pain score in the active tVNS group between the baseline and first follow-up visit, and between the baseline and second follow-up visit (P <0.001). The median VAS improvement was 4.0 (3.0 – 5.0) in active group versus 1.0 (1.0 – 2.0) in sham group (p <0.001). PPT in right knee, left knee and right elbow was significantly improved compared to baseline in active tVNS and maintained till 4-weeks post-intervention. On the other hand, in the sham group tVNS, right knee PPT was improved but not maintained. PainDETECT and DN4 questionnaires were statistically improved in active tVNS (p <0.001). In contrast, DN4 questionnaire showed no improvement at all and PainDETECT showed improvement that was not maintained at the end of follow up in sham group. A statistically significant improvement in HADS immediately post intervention in active and sham tVNS (p <0.001), this improvement was maintained only in the active group 4 weeks after intervention. Regarding functional outcomes, the improvement in KOOS was significant in the active group only (31.44 ± 18.49, p > 0.001). No serious adverse events were reported in both study groups.ConclusionThis study provides preliminary evidence for the beneficial effects of tVNS in OA and raises the possibility of using neuromodulation as an add-on treatment to existing pharmacological and non-pharmacological measures.REFERENCES:NIL.Acknowledgements:NIL.Disclosure of InterestsNone Declared.