Low-temperature internal quantum efficiency of GaInN/GaN quantum wells under steady-state conditions

We compare the low-temperature photoluminescence (PL) intensities of a range of GaInN/GaN quantum well (QW) structures under identical excitation conditions, mounting the samples side by side. Normalizing the measured intensity to the absorbed power density in the QWs, we find that low-temperature PL efficiencies of several samples, which show close to 100% IQE in time-resolved PL, saturate at nearly an identical value. Of course, this is strong indicative of being 100% IQE at low temperature for those efficient samples. Using the low-temperature PL efficiency as a ``Reference'', on the other hand, we observe not only the effects of temperature-independent non-radiative losses on the low-temperature IQE, but also are able to determine the IQE of arbitrary samples on an absolute scale. Furthermore, we prove the experimental results by comparing the low-temperature efficiencies of a sample with an initial 100% IQE after intentionally introducing structural defects with argon-implantation.

Optimization of performance of PV panels and selection of best site for solar park in Pakistan

To incorporate solar energy efficiently into a country, it is needed to know the optimal tilt and azimuth angle of the solar collectors' location. Also, to build a solar park, it is necessary to know the most suitable and high-energy generating place inside a country, thus saving time and money. This study analyzed collector geometry for Karachi in particular and Pakistan in general. Karachi has the potential of 339.36 kW-hr/m2/annum energy at an annually optimal fixed tilt of 26°. In case collector geometry had to be changed in Karachi, a range of 40° azimuth angle and 20° tilt angle from its maximum value is available. The power produced in this case would only have a difference of 1%. Optimal yearly and monthly tilt of most of the locations of Pakistan (300+) were calculated. Through them, it was revealed that the Optimal Tilt of Pakistan follows the value of latitude closely. Generally, changing the tilt angle monthly is recommended for areas that produce more energy, while fixed annual tilt could be suitable for low energy-producing regions. Effects of temperature were also incorporated while finding the energy produced by the photovoltaic (PV) panels.

Waste Pharmaceutical Blister Packages as a Source of Secondary Aluminum

Waste pharmaceutical blister packages (WPBs) are a source of solid waste, which are composed of plastics and aluminum, therefore acting as a potential source for secondary aluminum. The structure of WPBs makes the recycling of aluminum notably more complex than typical aluminum recycling. Currently, WBPs are disposed of as municipal solid waste; thus, aluminum is lost from the circulation during incineration. In this work, three types of WPBs were studied, each with two plastic layers and a metallic layer. Delamination of WPBs to separate aluminum and plastic(s) was investigated by using a solution of organic solvents. The effects of temperature (30–50°C), acetone to isopropanol ratio (0–100 vol.%) and different types of WPBs on delamination behavior were investigated. The results suggest that aluminum separation and recovery from WPBs is 100% at optimum conditions. Moreover, an overall indicative flowsheet for recycling and post-processing of segregated aluminum from the plastic is also suggested.