Prolonged intra-operative thermal exposure in endoscopic ear surgery: is it really safe?

ObjectiveThe aim of this study was to assess change in temperature, audiometric outcomes and post-operative complications following exposure to different light sources during endoscopic ear surgery.MethodA total of 64 patients diagnosed with chronic otitis media with central perforation and pure conductive hearing loss underwent endoscopic type 1 tympanoplasty. The patients were randomised into two groups based on the light source used: xenon or light-emitting diode. Temperature was measured using a K type thermocouple at the promontory and round window niche. Mean temperature change with respect to operating time, mean audiometric change, incidence of vomiting in the first 24 hours, vertigo and tinnitus at the end of the first week were observed.ResultsMean temperature change showed a statistically significant difference with increasing length of operating time with the xenon light source and when the two light sources were compared for a particular time interval. Mean audiometric change showed statistically significant deterioration at higher frequencies (4, 6 and 8 kHz) with the xenon light source but only at 8 kHz for the light emitting diode source. When the mean audiometric change was compared between light sources for a particular frequency, statistical significance was found at 4, 6 and 8 kHz. Post-operative complications were vomiting, vertigo and tinnitus (p-values of 0.042, 0.099 and 0.147, respectively, between two groups).ConclusionLight emitting diodes are associated with less significant middle-ear temperature rises and audiometric changes at higher frequencies when compared to xenon light sources. Hence, xenon should be replaced with cooler light sources.

Parathyroid Autofluorescence—How Does It Affect Parathyroid and Thyroid Surgery? A 5 Year Experience

Injury to parathyroid glands during thyroid and parathyroid surgery is common and postoperative hypoparathyroidism represents a serious complication. Parathyroid glands possess a unique autofluorescence in the near-infrared spectrum which could be used for their identification and protection at an early stage of the operation. In the present study parathyroid autofluorescence was visualized intraoperatively using a standard Storz laparoscopic near-infrared/indocyanine green (NIR/ICG) imaging system with minor modifications to the xenon light source (filtered to emit 690 nm to 790 nm light, less than 1% in the red and green above 470 nm and no blue light). During exposure to NIR light parathyroid tissue was expected to show autofluorescence at 820 nm, captured in the blue channel of the camera. Over a period of 5 years, we investigated 205 parathyroid glands from 117 patients. 179 (87.3%) glands were correctly identified by their autofluorescence. Surrounding structures such as thyroid, lymph nodes, muscle, or adipose tissue did not reveal substantial autofluorescence. We conclude that parathyroid glands can be identified by their unique autofluorescence at an early stage of the operation. This may help to preserve these fragile structures and their vascularization and lower the rate of postoperative hypocalcemia.

Concentrated Solar Radiation Simulation For Space Solar Power Module Vacuum Testing

Space Solar Power (SSP) is broadly defined as the collection of solar energy in space and its wireless transmission for use on Earth. The implementation of such a system could offer energy security, environmental, and technological advantages. The Integrated Symmetrical Concentrator (ISC) and Modular Symmetrical Concentrator (MSC) concepts have received considerable attention among recent commonly proposed SSP implementations. Each concept employs an array of modules for performing conversion of concentrated sunlight into microwaves for transmission to Earth. Until the efforts of the U.S. Naval Research Laboratory, no module prototypes had been subjected to the challenging conditions inherent to the space environment. The customized space simulation testing and the associated development described in this paper detail the efforts to test a prototype module in vacuum under multiple suns of solar concentration. A small vacuum chamber and 4000W Xenon light source were adapted to provide the desired test conditions. In particular, much effort was devoted to arriving at an effective, inexpensive solution that was consistent with the budget constraints of the project without compromising the fidelity and relevance of the tests.

LIGHT INDUCED CHANGE IN CONDUCTIVITY OF GRAPHENE OXIDE FILMS PATTERNED BY METAL MASKS

Micron-scale ordered gold patterns were deposited through a metallic copper grid positioned onto graphene oxide (GO) film. The exposure to a xenon light source results in the formation of conductive GO/metal interface with photocurrent generation. It is suggested that such simple method might serve as an efficient path for the formation of multifunctional patterned metal-carbon interconnects.

Plasma etching of polystyrene latex particles for the preparation of graphene oxide nanowalls

Graphene oxide nanowalls were prepared by casting a water dispersion of polystyrene latex particles onto a graphene oxide film followed by tetrafluoromethane plasma etching. Mild plasma etching conditions allow one to retain the oxygen functional groups on the graphene oxide nanowalls. It was found that the exposure to a xenon light source of such graphene oxide nanowalls coated with a gold thin film results in an increase of the electrical conductivity.