Intermediate Mirrors to Reach Theoretical Efficiency Limits of Multi-Bandgap Solar Cells

Creating a single bandgap solar cell that approaches the Shockley-Queisser limit requires a highly reflective rear mirror. This mirror enhances the voltage of the solar cell by providing photons with multiple opportunities for escaping out the front surface. Efficient external luminescence is a pre-requisite for high voltage. Intermediate mirrors in a multijunction solar cell can enhance the voltage for each cell in the stack. These intermediate mirrors need to have the added function of transmitting the below bandgap photons to the next cell in the stack. In this work, we quantitatively establish the efficiency increase possible with the use of intermediate selective reflectors between cells in a tandem stack. The absolute efficiency increase can be up to ~6% in dual bandgap cells with optimal intermediate and rear mirrors. A practical implementation of an intermediate selective mirror is an air gap sandwiched by antireflection coatings. The air gap provides perfect reflection for angles outside the escape cone, and the antireflection coating transmits angles inside the escape cone. As the incoming sunlight is within the escape cone, it is transmitted on to the next cell, while most of the internally trapped luminescence is reflected

Structural insight into palladium-nickel clusters over mordenite zeolite for carbene-insertion reaction

The advancement of heterogeneous catalysts incorporating metal clusters in the nanometric size range has garnered significant attention due to their extraordinary catalytic activity and selectivity. The detailed characterization and understanding of the atomic structure of these metal clusters within catalysts is crucial for elucidating the underlying reaction mechanisms. In the present study, a distinctive three-atom PdNi cluster, characterized by two Pd atoms at terminal positions and a central Ni atom, was synthesized over mordenite zeolite. The presence of atomic PdNi clusters within the eight-membered ring side pocket area was confirmed by multiple advanced analytical techniques, including magic-angle spinning nuclear magnetic resonance spectroscopy, synchrotron X-ray powder diffraction, extended X-ray absorption fine structure spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy. The catalytic activity of the confined active species was examined by the carbene-mediated reactions of ethyl-2-diazoacetate to ethyl-2-methoxyacetate as a model reaction. Compared to the Pd-mordenite and Ni-mordenite, the PdNi-mordenite catalyst incorporates a PdNi cluster, which demonstrates a superior performance, achieving 100% conversion and high selectivity under the same reaction conditions. Our study elucidates the potential of constructing bimetallic clusters in zeolites, providing valuable insights for developing new heterogeneous catalysts applicable to a wide range of catalytic processes

Porosity-engineered carbons for supercapacitive energy storage using conjugated microporous polymer precursors

Conjugated microporous polymers (CMPs) are considered an important material, combining aspects of both microporosity and extended π-conjugation. However, pristine CMP electrodes suffer from poor electrical conductivity which limits the material in electrochemical applications. In this work, direct carbonisation of conjugated microporous polymers (CMPs) yields porosity-engineered carbons, important for the flow of ions through the electrode. These conductive carbonised CMPs show specific capacitance as high as 260 F g−1, excellent rate capability and no loss in performance after 10 000 charge/discharge cycles. This study provides a procedure to enhance the performance of CMP-based materials, opening up a new source of electroactive materials

Evaluation of hazardous airborne carbonyls in five urban roadside dwellings: A comprehensive indoor air assessment in Sri Lanka

Indoor hazardous airborne carbonyls were quantified in five natural-ventilated roadside dwellings in Colombo, Sri Lanka. The total concentrations of all targeted carbonyls ranged from 13.6 to 18.6 mu g/m(3). Formaldehyde (C1) was the most abundant carbonyl, followed by acetaldehyde (C2) and acetone (C3K). The concentrations of C1 and C2 ranged from 3.3 to 8.5 mu g/m(3) and 2.3 to 4.4 mu g/m(3), respectively, which accounted for 23 to 42% and 18 to 26% respectively, to the total quantified carbonyls. The highest carbonyls levels were obtained in the dwelling located in an urban district with a mixture of industrial, commercial and residential areas. Much lower concentrations of carbonyls were measured in a light local traffic value was counted. Moderate correlations between individual combustion markers from vehicular emissions suggest the strong impacts from traffics to the indoor airs. The concentrations of C1 and C2 were compared with international indoor guidelines established by different authorities. A health assessment was conducted by estimation of inhalation cancer risk, implementing the inhalation unit risk values provided by Integrated Risk Information System (IRIS), associated with C1 and C2, which were 6.2 x 10(-5) and 7.7 x 10(-6), respectively. Even though the risks did not reach the action level (1 x 10(-4)), their health impact should not be overlooked. This kick-off indoor monitoring study provides valuable scientific data to the environmental science community since only limit data is available in Sri Lanka

Integrating Complementary Medicine Into the Care of Childhood Cancer Survivors: A Brief Report on the Preliminary Framework and Implementation of an Educational Program

BackgroundExisting educational programs typically include limited information on traditional, complementary, and integrative medicine (TCIM) for survivors of childhood cancer.ObjectivesThis brief report presents the preliminary results of an educational program that aims to promote the safe and effective use of Chinese medicine (CM) among survivors in Hong Kong.MethodsSurvivors of childhood cancer, their caregivers, and oncology practitioners were invited to participate in a program that consists of two didactic seminars and a written educational booklet that disseminated information on the use of CM. A structured questionnaire was used to evaluate participants' receptivity toward and perceived relevance of the program. The Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework was used to discuss the impact of the intervention.ResultsReach: A total of 174 participants attended the seminars, and the seminar recording received over 380 views on social media platforms since April 2021. The hardcopy of the educational booklet was distributed to 43 recipients. The web-version of the booklet was sent to 67 participants and downloaded 143 times. Efficacy: The majority found that the content of the seminar useful (mean score = 5.04/6 points), especially the CM exercise (mean score = 4.88/6 points) and dietary advice (mean score = 4.99/6 points). Intention to adopt: The survivors (or their caregivers) reported that they would adopt advice on food therapies (83.3%) and traditional Chinese health exercises (55.6%) during survivorship.ConclusionThe preliminary data on patient preferences will be applied to further develop educational materials and to establish a TCIM referral network within the cancer survivor community