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Perovskite photovoltaics, typically based on a solution-processed perovskite layer with a film thickness of a few hundred nanometres, have emerged as a leading thin-film photovoltaic technology. Nevertheless, many critical issues pose challenges to its commercialization progress, including industrial compatibility, stability, scalability and reliability. A thicker perovskite film on a scale of micrometres could mitigate these issues. However, the efficiencies of thick-film perovskite cells lag behind those with nanometre film thickness. With the mechanism remaining elusive, the community has long been under the impression that the limiting factor lies in the short carrier lifetime as a result of defects. Here, by constructing a perovskite system with extraordinarily long carrier lifetime, we rule out the restrictions of carrier lifetime on the device performance. Through this, we unveil the critical role of the ignored lattice strain in thick films. Our results provide insights into the factors limiting the performance of thick-film perovskite devices.

Abstract MicroRNA (miRNA) is a type of endogenous non-coding small RNA, which is abundant in living organisms. miRNAs play an important role in regulating gene expression and myriad cellular processes by binding to target messenger RNAs through complementary base pairing, and cross-species regulation mammalian cells by plant-derived xeno-miRNAs has been described. Here, we examined the miRNA species in two alfalfa (Medicago sativa, lucerne) cultivars commonly grown in Ningxia, China: cv. Zhongmu 1 and cv. Xinyan 52. Both cultivars have good salt and drought resistance. We found that the miRNA profiles were similar between the cultivars, with a slightly higher number of miRNAs present in the newer cv. Xinyan 52, which may contribute to its improved salt and drought tolerance. miRNAs were stable during drying, and some miRNAs were increased in dry versus fresh alfalfa, suggesting some miRNAs may be upregulated during drying. Alfalfa-derived miRNAs could be detected in exosomes from serum and whey collected from dairy cows, confirming the ability of the exogenous miRNAs (xeno-miRNAs) to enter the circulation and reach the mammary epithelium. In vitro studies confirmed that overexpression of mtr-miR156a could downregulate expression of Phosphatase 2 Regulatory Subunit B'gamma ( PPP2R5D) and Phosphoinositide-3-kinase Regulatory Subunit 2 (PIK3R2). Overexpression of mtr-miR156a also modulated PI3K–AKT–mTOR signaling as well as the casein content of milk produced by bovine mammary epithelial cells. Based on the known roles of PPP2R5D and PIK3R2 in regulating the PI3K–AKT–mTOR pathway as well as the effect of PI3K–AKT–mTOR on milk protein content, our findings implicate alfalfa-derived miR156a as a new cross-species regulator of milk quality in dairy cows.

In order to explore the quality characteristics of ‘Akizuki’ pear fruit (Pyrus pyrifolia) from different regions, the quality indexes of pear fruit from six geographical origins were determined, and gas chromatography-ion mobility spectrometry (GC-IMS) was used to determine their volatile aromatic compounds. The results showed that the titratable acid content of pear fruit from Ningling, Henan province was significantly higher than that of pear fruit from the other regions. There were significant differences in the contents of soluble solids, total flavonoids, and total phenols among some regions (P < 0.05). Totally 76 volatile aroma components were identified in the pericarp and pulp of pear fruit from the six different regions, including 23 esters, 20 aldehydes, 11 alcohols, 4 ketones, 1 olefin, 3 acids, and 14 other compounds. There were 24 more volatile aroma components in the pericarp than in the pulp. The unique volatile aroma components including isobutyl acetate, methyl butyrate, and isovaleraldehyde were detected in pear fruit from Weixian, Hebei province when compared with the other regions. Similarity analysis from fingerprints showed clear distinction among pear fruit from different regions. This study has provided information about the quality and aroma characteristics of ‘Akizuki’ pear fruit from different regions, and demonstrated that GC-IMS has potential application prospects for geographical origin differentiation and traceability of ‘Akizuki’ pear fruit.

Background With the promotion of "strengthening the primary care" measures, the number of primary healthcare professionals in China has increased significantly, but there is still a gap between the capacity of primary care physicians and basic medical needs of residents. Objective To understand the current situation of the medical service capacity of primary care physicians in different regions and between urban and rural areas of China, explore the strategies to improve the medical service capacity of primary care physicians in China. Methods In August 2020, an online questionnaire survey on 8 537 primary care physicians in the primary care institutions in eastern, central and western China by using the method of multi-stage stratified sampling combined with typical sampling. The questionnaire was designed based on the indexes in the part of medical service of the medical service capacity evaluation tool of primary care physicians previously developed by the research group, which was used to evaluate the competence of primary care physicians in four aspects of diagnosis and treatment of common diseases and frequent diseases, emergency treatment of critical illnesses, medical service coordination and traditional Chinese medicine services and assess the extent to which their competence met the needs of their work. The competence of primary care physicians and the extent to which their competence met the needs of their work were compared in different regions and levels of medical institutions. Results A total of 8 469 valid questionnaires were collected, with the recovery rate of 99.2%. There were 6 954 (82.1%), 4 283 (50.6%), 4 800 (56.7%) and 4 464 (52.7%) primary care physicians who had the ability of diagnosis and treatment of common diseases and frequent diseases, emergency treatment of critical illnesses, medical service coordination and traditional Chinese medicine services. The rate of medical competence of primary care physicians in the central region were higher than those in the eastern and western regions from the perspective of regional distribution, with statistically significant differences (P