YAG : R3+ (R = Ce, Dy, Yb) nanophosphor-based luminescent fibre-optic sensors for temperature measurements in the range 20–500 °C

We report the development of a group of luminescent fibre-optic temperature sensors that use Ce3+-, Dy3+-, and Yb3+-doped yttrium aluminium garnet (YAG) nanophosphors as thermosensitive materials. The nanophosphors have been prepared in the form of powders with a crystallite size from 19 to 27 nm by a polymer ? salt method and exhibit bright luminescence at 550 (YAG : Ce3+), 400, 480 (YAG : Dy3+), and 1030 nm (YAG : Yb3+). The sensor design includes a silica capillary, partially filled with a nanophosphor, and two large-aperture multimode optical fibres located in the capillary, which deliver excitation light and receive and transmit the photoluminescence signal. The photoluminescence signal amplitude of all the sensors decreases exponentially with increasing temperature, pointing to characteristic thermal quenching of photoluminescence and adequate operation of the devices up to 500 °C. The highest temperature sensitivity among the fibre-optic sensors is offered by the YAG : Ce3+ nanophosphor-based devices.

Soft X-ray spectra of Cerium laser-produced plasmas

Spectra of laser-produced plasmas of cerium have been recorded in the 1.5 to 15.5 nm spectral region. The plasmas were formed using the frequency doubled pulsed output of a neodymium-doped yttrium aluminium garnet (Nd:YAG) laser at 532 nm. At the power densities incident on-target, ranging from 8.6×109- 2.1×1013W cm-2, Ce4+ to Ce27+ ions gave rise to emission from ∆n = 0, 1 transitions to final states where n = 4. The spectra are dominated by an intense unresolved transition array (UTA) in the 8-10 nm region arising from n = 4 to n = 4 transitions. Two distinct components of this UTA are observed whose appearance is strongly dependent on laser power density, corresponding to transitions involving ions with open 4d and open 4f subshells, the latter at longer wavelengths. Multiple other transition arrays are identified and UTA statistics are given. The analysis was aided by atomic structure calculations and the use of a steady state collisional-radiative (CR) model.

Comparing the effects and safety of dorzolamide hydrochloride + timolol maleate versus brimonidine after neodymium-doped yttrium aluminium garnet laser capsulotomy posterior capsule opacification

Aim Posterior capsular opacification is treated using neodymium-doped yttrium aluminium garnet laser capsulotomy that leads to increased intraocular pressure. Here, we compare the effects of dorzolamide hydrochloride + timolol maleate versus brimonidine on intraocular pressure. We also investigate their side effects after neodymium-doped yttrium aluminium garnet laser capsulotomy. In these patients, there are no prior studies comparing the results of these two drugs. Materials Ninety patients with posterior capsule opacification contributed to the study. They received yttrium aluminium garnet laser capsulotomy. After yttrium aluminium garnet laser capsulotomy, they were randomized into three groups. Group 1 received dorzolamide hydrochloride + timolol maleate; Group 2 took brimonidine; and Group 3, the control group, took no drug. Group 1 took dorzolamide hydrochloride + timolol maleate eye drops 1 h before the procedure and on the third hour of the first day and two times per day between the second and the seventh days. Group 2 took brimonidine eye drops 1 h before the procedure and on the third hour of the first day, two times per day between the second and the seventh days. Results Brimonidine had a similar side effect profile to the fix combination. Intraocular pressure on the first ( p = 0.87) and third days ( p = 0.124) were similar in Group 1 (dorzolamide hydrochloride + timolol maleate), Group 2 (brimonidine) and the control group. The mean intraocular pressure value of the control group was significantly higher than Groups 1 and 2 because the anti-glaucomatous effects of the drugs become prominent on the seventh day ( p = 0.041). In Group 1 and Group 2, intraocular pressure was significantly lower than the control group on the seventh day ( p = 0.041). Stinging, itching, hyperemia and Tyndall rates were similar in Group 1, Group 2 and the control group. Watery eyes were less common in the brimonidine group than in the dorzolamide hydrochloride–timolol maleate and the control groups on the seventh day ( p = 0.02). Brimonidine also significantly lowered the chemosis rate on the third ( p = 0.04) and seventh ( p = 0.03) days. Conclusion We suggest that brimonidine and a combination of dorzolamide + timolol are similarly effective at reducing eye pressure for routine cases. In cases where intraocular pressure attacks might be at higher risk, using the dorzolamide + timolol combination would be more appropriate.

Novel Ideas for Thermal Management of Filament LED Light Bulbs

The thermal conditions of a filament LED retro light bulb has been investigated. In such light bulbs, LEDs are mounted on filaments which have glass or sapphire substrate and are surrounded by yttrium-aluminium-garnet (YAG). Heat management is challenging as a heatsink cannot normally be used. Instead, heat removal is enabled by using helium as the filling gas. As this provides less efficient heat removal than using a heatsink attached directly to an LED module, LEDs operate in filament LED bulbs typically at rather high temperatures. In this paper thermal performance of a typical filament LED bulb has been studied. LED temperatures and gas flows inside the bulb has been resolved for cases of different orientations of the bulb. Thermal conditions for different filling gases have been resolved. All this has been done using finite element method (FEM) simulations. The main target of this study has been to find out novel solutions for thermal management of filament LED bulbs. Two heat removal solutions have been studied, namely the use of an internal heatsink and an internal piezoelectric oscillating cantilever fan. The results show that solutions can indeed reduce temperature of LED chips and increase the lifespan of the LED bulb.

Role of Erbium: YAG Laser in Management of Cutaneous Warts

Cutaneous warts are one of the commonest presenting complaints of patients reporting to Dermatology OPD. Most of the warts are viral in origin and they can be either single or multiple. Their morphology varies from flat-topped, angulated, filiform etc. Nowadays, various options are available for management of warts which include topical application of medications, surgical excision and laser treatment. Conventionally, CO2 laser has been used for treatment of warts but Erbium: yttrium aluminium-garnet (YAG) laser is one of the lasers which has recently come into the literature for treatment of warts. This study highlights our experience of using of Erbium: YAG laser in the management of cutaneous warts.