Photonic crystal enhancement and tuning of quantum dot emission

The work presented in this dissertation demonstrates various methods and approaches for photonic crystals (PCs) to enhance the output emission and performance of quantum dots (QDs). We integrate visible wavelength emitting QDs within a polymer-based photonic crystal and excite them using an ultraviolet-emitting LED. The PC design incorporates two interleaved regions, each with distinct periods in orthogonal directions to enable simultaneous resonant coupling of ultraviolet excitation photons to the QDs and visible QD emission at two different wavelengths to efficiently extract photons normal to the PC surface. The combined excitation and extraction enhancements result in a 5.8X increase in the QD output intensity. Further, we demonstrate multiple QD-doped PCs combined on a single surface to optimally couple with distinct populations of QDs, offering a means for blending color output and directionality of multiple wavelengths. Another replica molded PC is fabricated with embedded QDs in which electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the QD material and the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, enabling an 8X output enhancement and highly polarized emission from the PC structure. We demonstrate a method for combining sputtered TiO2 deposition with liquid phase dip-coating of a QD layer that enables precise depth placement of QD emitters within a high-index dielectric film, using a PC slab resonator to demonstrate enhanced emission from the QDs when they are located at a specific depth within the film. The depth of the QDs within the PC is found to modulate the resonant wavelength of the PC as well as the emission enhancement efficiency, as the semiconducting material embedded within the dielectric changes its spatial overlap with the resonant mode. The first real-time tuning of PC-enhanced QD emission is successfully performed by fabricating QD embedded PCs on the surface of an acoustic MEMs resonator. As the RF modulation deforms the piezoelectric material of the resonator, the surface PC is also deformed. The coupling wavelength of the PC is modulated away from the QD emission wavelength, producing measurable variation in the output intensity of the QD emission. By tailoring the design and fabrication of QD-embedded PCs, significant improvements in device efficiency and production costs can be realized for utilizing QDs in lighting and display applications

Status of care for end stage kidney disease in countries and regions worldwide:international cross sectional survey

ObjectiveTo determine the global capacity (availability, accessibility, quality, and affordability) to deliver kidney replacement therapy (dialysis and transplantation) and conservative kidney management.DesignInternational cross sectional survey.SettingInternational Society of Nephrology (ISN) survey of 182 countries from July to September 2018.ParticipantsKey stakeholders identified by ISN's national and regional leaders.Main outcome measuresMarkers of national capacity to deliver core components of kidney replacement therapy and conservative kidney management.ResultsResponses were received from 160 (87.9%) of 182 countries, comprising 97.8% (7338.5 million of 7501.3 million) of the world's population. A wide variation was found in capacity and structures for kidney replacement therapy and conservative kidney management-namely, funding mechanisms, health workforce, service delivery, and available technologies. Information on the prevalence of treated end stage kidney disease was available in 91 (42%) of 218 countries worldwide. Estimates varied more than 800-fold from 4 to 3392 per million population. Rwanda was the only low income country to report data on the prevalence of treated disease; 5 (<10%) of 53 African countries reported these data. Of 159 countries, 102 (64%) provided public funding for kidney replacement therapy. Sixty eight (43%) of 159 countries charged no fees at the point of care delivery and 34 (21%) made some charge. Haemodialysis was reported as available in 156 (100%) of 156 countries, peritoneal dialysis in 119 (76%) of 156 countries, and kidney transplantation in 114 (74%) of 155 countries. Dialysis and kidney transplantation were available to more than 50% of patients in only 108 (70%) and 45 (29%) of 154 countries that offered these services, respectively. Conservative kidney management was available in 124 (81%) of 154 countries. Worldwide, the median number of nephrologists was 9.96 per million population, which varied with income level.ConclusionsThese comprehensive data show the capacity of countries (including low income countries) to provide optimal care for patients with end stage kidney disease. They demonstrate substantial variability in the burden of such disease and capacity for kidney replacement therapy and conservative kidney management, which have implications for policy