Planar quasi-Yagi antenna gain enhancement using zero-index metamaterials

In this letter we have applied a new anisotropic zero index metamaterial (ZIM) structure to the quasi-Yagi antenna to achieve a high-directivity quasi-Yagi antenna. Simulation results show that the antenna gain increases for a frequency range over which the proposed metamaterial structure exhibits ZIM properties (10.3-11.7 GHz)

Evaluation of thermally stable phosphor screens for application in laser diode excited high brightness white light modules

A study on the preparation of thermally stable phosphor targets based on yttrium aluminum garnet doped with cerium (YAG:Ce) when excited by a high power laser diode is described. The luminous flux, chromaticity and radial spectral flux of the targets along with their thermal stability have been determined when exposed to laser powers of up to 5000 mW. This report presents successful high brightness light sources with adjustable emission properties achieved by utilizing thermally stable phosphor targets excited by high power laser diodes.Brunel University London, No. EP/K504208/

Optical analysis of RF sputtering plasma through colour characterization

© 2019 by the authors. The photometric properties of an radio frequency (RF)-based sputtering plasma source were monitored through optical spectroscopy. The colour of the plasma source was deduced based on conventional chromaticity index analysis and it was compared to the direct spectral data plots of the emission peaks to investigate the possibility of characterising the plasma based on its specific colour and exploring the potential of defining a new method by which the plasma sputtering process can be addressed based on the plasma colour parameters. The intention of this investigation is to evaluate the possibility of simplifying the monitoring and assessment of the sputtering process for applied scientists operating plasma sputter deposition systems. We demonstrate a viable potential for this technique in terms of providing information regarding the stability of the plasma, chamber pressure, and plasma power; however, further work is underway to verify and assess a relationship between the quality of the thin film coating and the colour characteristics of the deposition plasma. Here, we only focus on the feasibility of such an approach and demonstrate interesting observations. We observed a linear relationship between the colour functions and the plasma power, while the stability of the sputtering plasma can be assessed based on the plasma colour functions. The colour functions also follow a unique pattern when the working gas pressure is increased

Investigating the emission characteristics of single crystal YAG when activated by high power laser beams

© The Author(s) 2016. Limitations associated with light emitting diodes (LEDs) operating under high current densities due to the efficiency droop has created a need to look for alternative light sources; here we report investigations on the potential of laser diodes (LDs) for high brightness lighting solutions. High power laser diodes require phosphor targets with certain performance criteria such as high thermal conductivity, efficiency and structural geometry. Here we examine the possibility of using single crystal YAG:Ce phosphor materials as potential targets for generation of light via laser diodes. We report on the emission properties of the crystals with different sizes and examine the effect of laser beam incident angle incident on crystal target emission

Investigating the Emission Characteristics of Single Crystal YAG When Activated by High Power Laser Beams

© The Author(s) 2016. Limitations associated with light emitting diodes (LEDs) operating under high current densities due to the efficiency droop has created a need to look for alternative light sources; here we report investigations on the potential of laser diodes (LDs) for high brightness lighting solutions. High power laser diodes require phosphor targets with certain performance criteria such as high thermal conductivity, efficiency and structural geometry. Here we examine the possibility of using single crystal YAG:Ce phosphor materials as potential targets for generation of light via laser diodes. We report on the emission properties of the crystals with different sizes and examine the effect of laser beam incident angle incident on crystal target emission.We thank Brunel University London for allocation of funds from EPSRC grant No. EP/K504208/1 & APEX phase II program

Real World Estimates Of Adrenal Insufficiency Related Adverse Events In Children With Congenital Adrenal Hyperplasia.

BACKGROUND: Although congenital adrenal hyperplasia (CAH) is known to be associated with adrenal crises (AC), its association with patient or clinician reported sick day episodes (SDE) is less clear. METHODS: Data on children with classic 21-hydroxylase deficiency CAH from 34 centers in 18 countries, of which 7 were Low or Middle Income (LMIC) and 11 were High Income (HIC), were collected from the International CAH Registry and analysed to examine the clinical factors associated with SDE and AC. RESULTS: 518 children with a median of 11 children (range 1, 53) per center had 5,388 visits evaluated over a total of 2,300 patient years. The median number of AC and SDE per patient year per center was 0 (0, 3) and 0.4 (0.0, 13.3), respectively. Of the 1,544 SDE, an AC was reported in 62 (4%), with no fatalities. Infectious illness was the most frequent precipitating event, reported in 1,105 (72%) and 29 (47%) of SDE and AC, respectively. On comparing cases from LMIC and HIC, the median SDE per patient year was 0.75 (0, 13.3) vs 0.11 (0, 12.0) (p<0.001), respectively and the median AC per patient year was 0 (0, 2.2) vs 0 (0, 3.0) (p=0.43), respectively. CONCLUSIONS: The real-world data that are collected within the I-CAH Registry show wide variability in the reported occurrence of adrenal insufficiency related adverse events. As these data become increasingly used as a clinical benchmark in CAH care, there is a need for further research to improve and standardise the definition of SDE