Highly efficient planar perovskite solar cells through band alignment engineering

The simplification of perovskite solar cells (PSCs), by replacing the mesoporous electron selective layer (ESL) with a planar one, is advantageous for large-scale manufacturing. PSCs with a planar TiO2 ESL have been demonstrated, but these exhibit unstabilized power conversion efficiencies (PCEs). Herein we show that planar PSCs using TiO2 are inherently limited due to conduction band misalignment and demonstrate, with a variety of characterization techniques, for the first time that SnO2 achieves a barrier-free energetic configuration, obtaining almost hysteresis-free PCEs of over 18% with record high voltages of up to 1.19 V

The effects of stimulant medications on children’s growth velocity

Objective: This study sought to determine whether relationships exist between stimulant medications and children’s growth velocity.Methods: The investigators conducted a retrospective review of 280 charts of pre-pubertal children with attention-deficit hyperactivitydisorder (ADHD) who were prescribed stimulant medications for a minimum of 1 year. The children were patients in a university childdevelopment/ADHD clinic. Results: The average growth velocity across all genders and ages was 5.72 cm/year (females 5.53 cm/year,males 5.28 cm/year). The majority of the children had growth velocities in the 25-50th percentiles for age. Conclusion: This study didnot find evidence of significant effect on growth velocity in children with ADHD treated with stimulant medications. Our results concurwith the majority of other studies of growth in children taking stimulant medications for ADHD management. It supports our continuedprescription of stimulant medications without concern for slowed or stunted growth in our patients with ADHD

Quasi-dynamic analysis, design optimization, and evaluation of a two-finger underactuated hand

Underactuated hands are able to achieve shape adaptation to conformally grasp a wide variety of objects, while keeping low undesirable hand attributes such as weight, size, complexity and cost. The available analytical and simulation studies of planar underactuated hands normally assume quasi-static conditions and a fixed object. In the present paper, a new quasi-dynamic analysis of the grasping process in the horizontal plane by a planar, two-finger, four-joint underactuated hand is presented. The study considers object movement during the grasping process, and also contact friction with a surface that supports the object. An extensive and versatile simulation program, based on the analysis, is developed to investigate the effects of various parameters of hand and object on the grasping process. A prototype hand has been developed and the simulation results are validated experimentally. An extensive and detailed study and optimization exercise is carried out using the developed simulation tool. Specifically, the study concerns a manipulative grasping process that moves the object to the hand centerline during the process. Important new findings on the influence of link dimensions, link angular speeds, friction with the supporting surface, object mass and object size on the grasping performance of the hand in this scenario are presented. The results are used to establish new design guidelines for the hand. In particular, the results indicate that in the case where there is limited information on the size and precise initial location of the object to be grasped, the optimal hand design would involve inner to outer phalange size ratios of approximately 3:1, and inner phalange joints that are very close to each other.peer-reviewe

Room-Temperature Cubic Phase Crystallization and High Stability of Vacuum-Deposited Methylammonium Lead Triiodide Thin Films for High-Efficiency Solar Cells

Methylammonium lead triiodide (MAPI) has emerged as a high-performance photovoltaic material. Common understanding is that at room temperature it adopts a tetragonal phase and it only converts to the perfect cubic phase around 50-60 ºC. Most MAPI films are prepared using a solution-based coating process, yet they can also be obtained by vapor phase deposition methods. Vapor phase processed MAPI films have significantly different characteristics compared to their solvent processed analogous, such as a relatively small crystal grain sizes and short excited state lifetimes. Yet solar cells based on vapor phase processed MAPI films exhibit high power conversion efficiencies. Surprisingly, after detailed characterization we find that our vapor phase processed MAPI films adopt a cubic crystal structure at room temperature that is stable for weeks, even in ambient atmosphere. Furthermore, we demonstrate that by tuning the deposition rates of both precursors during co-deposition it is possible to vary the perovskite phase from cubic to tetragonal at room temperature. Our finding challenges the common belief that MAPI is only stable in tetragonal phase at room temperature. Additionally, these findings can be used to explain the somewhat unexpected high performance of solar cells based on vacuum processed MAPI films with sub 100 nm grain sizes and excited state lifetimes < 100 nanoseconds

Post-Hematopoietic Stem Cell Transplantation (HSCT) Outcomes in Patients With AML Transplanted Prior to Achieving Platelet Recovery

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Parents’ knowledge of and opinions about healthcare laws and technology in primary care

Purpose Historically, parents have demonstrated poor understanding of adolescent healthcare laws. This study assessed US parents’ current knowledge and opinions about technology facilitated physician–adolescent communication and applicable laws to enhance transition to adult health care.Methods A brief survey in two low-income academic paediatric clinics asked parents about their knowledge of health care and laws, and their opinions about technology facilitated contact between physicians and adolescents.Results Almost all parents (96.7%) have internet access at home, work or via a mobile device. Only 44.1% approved of having a physician directly contact their child about annual examinations, immunisations or to discuss issues of sexuality. Half (55.4%) were aware that adolescents could receive confidential sexuality information and treatment without parents’ permission. Only one-third (32.2%) approved of a specific technology for direct communication.Conclusions Parents are divided about direct physician–adolescent contact. Future plans to engage adolescents to understand their health will require parental education and involvement on the value of physician–adolescent communication

The hyperfine transition in light muonic atoms of odd Z

The hyperfine (hf) transition rates for muonic atoms have been re-measured for select light nuclei, using neutron detectors to evaluate the time dependence of muon capture. For $^{19}$F $\Lambda$$_{h}$ = 5.6 (2) $\mu$s$^{-1}$ for the hf transition rate, a value which is considerably more accurate than previous measurements. Results are also reported for Na, Al, P, Cl, and K; that result for P is the first positive identification.Comment: 12 pages including 5 tables and 4 figures, RevTex, submitted to Phys. Rev.