2,404 research outputs found

    Solution-Processed, Solid-State Solar Cells based on Environmentally Friendly AgBiS2 Nanocrystals

    Get PDF
    Solution-processed inorganic solar cells are a promising low-cost alternative to firstgeneration solar cells.1,2 Solution processing at low temperatures and the use of nontoxic and abundant elements can help minimize cost and facilitate regulatory acceptance. However, until now there has been no material that exhibits all of these features while demonstrating promising efficiencies. Many of the most promising solution-processed inorganic solar cells contain toxic elements such as lead or cadmium (perovskites,2,3 PbS,4 CdTe,5,6 CdS(Se)7,8) or scarce elements like tellurium or indium (CdTe, CIGS(Se)/CIS9,10). Others require high-temperature processes such as selenization or sintering or rely on vacuum deposition techniques ((Sb2S(Se)3,11–13 SnS,14,15 CZTS(Se)16). Here, we present AgBiS2 nanocrystals as a novel nontoxic,17 earth-abundant18 material for highperformance, solution-processed solar cells fabricated in ambient conditions at low temperatures (≤100°C). The AgBiS2 nanocrystals have favorable properties for solar-cell applications including a near-ideal bandgap and strong, broad absorption. We demonstrate a Newport certified power conversion efficiency of 6.3% with no hysteresis and a remarkably high short-circuit current density of about 22 mA·cm-2 for an active layer thickness of only ~35 nm.Peer ReviewedPostprint (author's final draft

    EvoPrompting: Language Models for Code-Level Neural Architecture Search

    Full text link
    Given the recent impressive accomplishments of language models (LMs) for code generation, we explore the use of LMs as adaptive mutation and crossover operators for an evolutionary neural architecture search (NAS) algorithm. While NAS still proves too difficult a task for LMs to succeed at solely through prompting, we find that the combination of evolutionary prompt engineering with soft prompt-tuning, a method we term EvoPrompting, consistently finds diverse and high performing models. We first demonstrate that EvoPrompting is effective on the computationally efficient MNIST-1D dataset, where EvoPrompting produces convolutional architecture variants that outperform both those designed by human experts and naive few-shot prompting in terms of accuracy and model size. We then apply our method to searching for graph neural networks on the CLRS Algorithmic Reasoning Benchmark, where EvoPrompting is able to design novel architectures that outperform current state-of-the-art models on 21 out of 30 algorithmic reasoning tasks while maintaining similar model size. EvoPrompting is successful at designing accurate and efficient neural network architectures across a variety of machine learning tasks, while also being general enough for easy adaptation to other tasks beyond neural network design

    Cut points in abcohesive, aposyndetic, and semi-locally connected spaces

    Get PDF
    In 1941, F. B. Jones introduced aposyndesis, which generalizes the concept of semi-local connectedness defined earlier by G. T. Whyburn (1942), in the study of continuum theory. Using Jones's idea, D. A. John (1993) defined abcohesiveness as a generalization of aposyndesis and studied the A-sets in abcohesive spaces. In this paper, some properties of abcohesive spaces are studied and a number of results by B. Lehman (1976) and Whyburn (1942, 1968) are generalized; sufficient conditions for the existence of two nodal sets are established as well

    Sheehan's Syndrome; A Rare Complication of Postpartum Hemorrhage - Case Report and Review of the Literature

    Get PDF
    Sheehan Syndrome is a Condition that may occur in a woman who bleeds severely during child birth. Severe bleeding during child birth can cause tissue death in the pituitary gland, which may cause the +0 gland to lose its ability to function properly. We reported a case of a 21 year old lady gravida 1 para 1 (alive) who developed Sheehan's syndrome six months after extreme post partum hemorrhage. High level of suspicious was employed based on clinical history and couple with the laboratory blood tests and magnetic resonance Imaging (MRI) findings in arriving at diagnosis of this rare complication of lifethreatening blood loss during or after child birth. We also highlighted the importance of proper medical care in preventing extreme bleeding during child birth, otherwise, Sheehan's syndrome is not preventable.Keywords: Sheehan's Syndrome, Post Partum Hemorrhag
    • …
    corecore