| 1. |
- Bao, Chunxiong, et al.
(author)
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High Performance and Stable All-Inorganic Metal Halide Perovskite-Based Photodetectors for Optical Communication Applications
- 2018
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In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:38
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Journal article (peer-reviewed)abstract
- Photodetectors are critical parts of an optical communication system for achieving efficient photoelectronic conversion of signals, and the response speed directly determines the bandwidth of the whole system. Metal halide perovskites, an emerging class of low-cost solution-processed semiconductors, exhibiting strong optical absorption, low trap states, and high carrier mobility, are widely investigated in photodetection applications. Herein, through optimizing the device engineering and film quality, high-performance photodetectors based on all-inorganic cesium lead halide perovskite (CsPbIxBr3-x), which simultaneously possess high sensitivity and fast response, are demonstrated. The optimized devices processed from CsPbIBr2 perovskite show a practically measured detectable limit of about 21.5 pW cm(-2) and a fast response time of 20 ns, which are both among the highest reported device performance of perovskite-based photodetectors. Moreover, the photodetectors exhibit outstanding long-term environmental stability, with negligible degradation of the photoresponse property after 2000 h under ambient conditions. In addition, the resulting perovskite photodetector is successfully integrated into an optical communication system and its applications as an optical signal receiver on transmitting text and audio signals is demonstrated. The results suggest that all-inorganic metal halide perovskite-based photodetectors have great application potential for optical communication.
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| 2. |
- Feng, Tongbao, et al.
(author)
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miR-124 inhibits cell proliferation in breast cancer through downregulation of CDK4
- 2015
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In: Tumor Biology. - : Springer Science and Business Media LLC. - 1423-0380 .- 1010-4283. ; 36:8, s. 5987-5997
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Journal article (peer-reviewed)abstract
- Studies have shown that microRNAs (miRNAs) are involved in the malignant progression of human cancer. However, little is known about the potential role of miRNAs in breast carcinogenesis. miR-124 expression in breast cancer tissue was measured by quantitative real-time PCR (qRT-PCR). Target prediction algorithms and luciferase reporter gene assays were used to investigate the target of miR-124. Breast cancer cells growth was regulated by overexpression or knockdown miR-124. At the end of the study, tumor-bearing mice were tested to confirm the function of miR-124 in breast cancer. In this study, we demonstrated that the expression of miR-124 was significantly downregulated in breast cancer tissues compared with matched adjacent non-neoplastic tissues. We identified and confirmed that cyclin-dependent kinase 4 (CDK4) was a direct target of miR-124. Overexpression of miR-124 suppressed CDK4 protein expression and attenuated cell viability, proliferation, and cell cycle progression in MCF-7 and MDA-MB-435S breast cancer cells in vitro. Overexpression of CDK4 partially rescued the inhibitory effect of miR-124 in the breast cancer cells. Moreover, we found that miR-124 overexpression effectively repressed tumor growth in xenograft animal experiments. Our results demonstrate that miR-124 functions as a growth-suppressive miRNA and plays an important role in inhibiting tumorigenesis by targeting CDK4.
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| 3. |
- Xu, Yan, et al.
(author)
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Impact of Amine Additives on Perovskite Precursor Aging : A Case Study of Light-Emitting Diodes
- 2021
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In: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 12:25, s. 5836-5843
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Journal article (peer-reviewed)abstract
- Amines are widely employed as additives for improving the performance of metal halide perovskite optoelectronic devices. However, amines are well-known for their high chemical reactivity, the impact of which has yet to receive enough attention from the perovskite light-emitting diode community. Here, by investigating an unusual positive aging effect of CH3NH3I/CsI/PbI2 precursor solutions as an example, we reveal that amines gradually undergo N-formylation in perovskite precursors over time. This reaction is initialized by hydrolysis of dimethylformamide in the acidic chemical environment. Further investigations suggest that the reaction products collectively impact perovskite crystallization and eventually lead to significantly enhanced external quantum efficiency values, increasing from similar to 2% for fresh solutions to greater than or similar to 12% for aged ones. While this case study provides a positive aging effect, a negative aging effect is possible in other perovksite systems. Our findings pave the way for more reliable and reproducible device fabrication and call for further attention to underlying chemical reactions within the perovskite inks once amine additives are included.
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| 4. |
- Bao, Chunxiong, et al.
(author)
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Bidirectional optical signal transmission between two identical devices using perovskite diodes
- 2020
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In: NATURE ELECTRONICS. - : NATURE PUBLISHING GROUP. - 2520-1131. ; 3:3, s. 156-164
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Journal article (peer-reviewed)abstract
- A solution-processed perovskite diode that functions as both optical transmitter and receiver can be used to build a monolithic pulse sensor and a bidirectional optical communication system. The integration of optical signal generation and reception into one device-thus allowing a bidirectional optical signal transmission between two identical devices-is of value in the development of miniaturized and integrated optoelectronic devices. However, conventional solution-processable semiconductors have intrinsic material and design limitations that prevent them from being used to create such devices with a high performance. Here we report an efficient solution-processed perovskite diode that is capable of working in both emission and detection modes. The device can be switched between modes by changing the bias direction, and it exhibits light emission with an external quantum efficiency of over 21% and a light detection limit on a subpicowatt scale. The operation speed for both functions can reach tens of megahertz. Benefiting from the small Stokes shift of perovskites, our diodes exhibit a high specific detectivity (more than 2 x 10(12) Jones) at its peak emission (~804 nm), which allows an optical signal exchange between two identical diodes. To illustrate the potential of the dual-functional diode, we show that it can be used to create a monolithic pulse sensor and a bidirectional optical communication system.
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| 5. |
- Frainer, André, 1982-, et al.
(author)
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No evidence for functional litter diversity effects on litter decomposition, fungal decomposers and nutrient immobilization
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Other publication (other academic/artistic)abstract
- Biodiversity and ecosystem functioning theory suggests that litter mixtures composed of dissimilar leaf species can enhance decomposition due to species trait complementarity. Here we create a continuous gradient of litter chemistry trait variability within species mixtures to assess effects of litter dissimilarity on three related processes in a natural stream: litter decomposition, fungal biomass accrual in the litter, and nitrogen and phosphorus immobilization. Litter from a pool of eight leaf species was analyzed for chemistry traits affecting decomposition (lignin, nitrogen, and phosphorus) and assembled in all of the 28 possible two-species combinations. Litter dissimilarity was characterized in terms of a range of functional diversity measures, using Euclidean and Gower distances and dendrogram-based indices. Despite favorable experimental conditions for litter dissimilarity effects to arise, we found no significant relationships between decomposition rate of individual leaf species and litter functional dissimilarity, irrespective of whether decomposition was mediated by microbes alone or by both microbes and litter-consuming invertebrates. Likewise, no effects of functional dissimilarity emerged on either fungal biomass accrual or changes during decomposition of nitrogen or phosphorus concentrations in individual leaf species. These results provide support for the contention that litter diversity effects on decomposition in streams are less pronounced than in forest environments, and in particular are less common than effects on terrestrial primary productivity. Key to understanding these discrepancies may be the constant supply of nutrients provided by the flowing water in streams, exacerbated by very large-scale cultural nutrient enrichment of surface waters in many parts of the world.
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| 6. |
- Frainer, André, et al.
(author)
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No evidence for leaf-trait dissimilarity effects on litter decomposition, fungal decomposers, and nutrient dynamics
- 2015
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In: Ecology. - : Ecological Society of America. - 0012-9658 .- 1939-9170. ; 96:2, s. 550-561
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Journal article (peer-reviewed)abstract
- Biodiversity and ecosystem-functioning theory suggest that litter mixtures composed of dissimilar leaf species can enhance decomposition due to species trait complementarity. Here we created a continuous gradient of litter chemistry trait variability within species mixtures to assess effects of litter dissimilarity on three related processes in a natural stream: litter decomposition, fungal biomass accrual in the litter, and nitrogen and phosphorus immobilization. Litter from a pool of eight leaf species was analyzed for chemistry traits affecting decomposition (lignin, nitrogen, and phosphorus) and assembled in all of the 28 possible two-species combinations. Litter dissimilarity was characterized in terms of a range of trait-diversity measures, using Euclidean and Gower distances and dendrogram-based indices. We found large differences in decomposition rates among leaf species, but no significant relationships between decomposition rate of individual leaf species and litter trait dissimilarity, irrespective of whether decomposition was mediated by microbes alone or by both microbes and litter-consuming invertebrates. Likewise, no effects of trait dissimilarity emerged on either fungal biomass accrual or changes during decomposition of nitrogen or phosphorus concentrations in individual leaf species. In line with recent meta-analyses, these results provide support for the contention that litter diversity effects on decomposition, at least in streams, are less pronounced than effects on terrestrial primary productivity.
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| 7. |
- Hua, Wenjing, et al.
(author)
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Genotypic and Phenotypic Analyses of Two "Isogenic" Strains of the Human Fungal Pathogen Cryptococcus neoformans var. neoformans
- 2019
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In: Mycopathologia. - : SPRINGER. - 0301-486X .- 1573-0832. ; 184:2, s. 195-212
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Journal article (peer-reviewed)abstract
- The Cryptococcus neoformans species complex is a model organism for fungal studies. Many studies have used two strains, JEC20 and JEC21, and their derivatives. These two strains were obtained through 10 rounds of backcrosses and have been assumed near identical except at the mating-type locus. Here we obtained and compared the JEC20 genome sequence with the published JEC21 genome. Our comparison revealed 5322 single nucleotide polymorphisms (SNPs) with the majority (N=3816, 71.7%) located in three genomic regions, including the previously noted mating-type region. The remaining 1506 SNPs (28.3%) were distributed throughout all 14 chromosomes, predominantly at chromosomal ends. To study the potential effects of these three SNP-rich regions on phenotypes, 24 progenies from the JEC20xJEC21 cross representing eight recombinant genotypes were analyzed for their mating ability, melanin production, capsule formation, and growths at 30 degrees C and 40 degrees C. Significant phenotypic variations were found among the progeny. However, the observed phenotypic variations could not be explained by the three SNP-rich regions. Further genome sequencing of our JEC21 and the 24 progenies revealed only six segregating SNPs outside of the three SNP-rich regions between JEC20 and JEC21, a result indicating that the 1500 SNPs identified in the published JEC21 genome might be caused by sequencing errors and/or strain mixing. However, the six SNPs and the three SNP-rich regions could not explain the observed phenotypic variations. Our analyses suggest that spontaneous mutations accumulated under laboratory conditions could have significant effects on phenotypes and on our interpretations of experimental results.
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| 8. |
- Li, Wenjing, et al.
(author)
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Spatial variation in the effects of air pollution on cardiovascular mortality in Beijing, China
- 2019
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In: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499.
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Journal article (peer-reviewed)abstract
- Due to lack of data from multiple air quality monitoring stations, studies about spatial association between concentrations of ambient pollutants and mortality in China are rare. To investigate the spatial variation of association between concentrations of particulate matter less than 10 μm in aerodynamic diameter (PM10) and nitrogen dioxide (NO2) and cardiovascular mortality in Beijing, China, we collected data including daily deaths, concentrations of PM10 and NO2, and meteorological factors from January 1, 2009, to December 31, 2010, in all 16 districts of Beijing. Generalized additive model (GAM) and generalized additive mixed model (GAMM) were used to examine the citywide and district-specific effects of PM10 and NO2 on cardiovascular mortality. The citywide effect derived from GAMM was lower than that derived from GAM and the strongest effects were identified for 2-day moving average lag 0–1. For every 10 μg/m3 increases in concentrations of PM10 and NO2, the corresponding daily cardiovascular mortality increases in 0.31% (95%CI 0.15%, 0.46%) and 1.63% (95%CI 1.11%, 2.13%), respectively. The death risk associated with air pollutants varied across different geographic districts in Beijing. We found spatially varied adverse effects of air pollution on cardiovascular deaths in Beijing. But there was insufficient evidence to show the significant spatial heterogeneity in mortality effects of PM10 and NO2 in this study.
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| 9. |
- Li, Wenjing, et al.
(author)
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The spatial variation in the effects of air pollution on cardiovascular mortality in Beijing, China
- 2018
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In: Journal of Exposure Science and Environmental Epidemiology. - : Nature Publishing Group. - 1559-0631 .- 1559-064X. ; 28:3, s. 297-304
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Journal article (peer-reviewed)abstract
- Owing to lack of data from multiple air quality monitoring stations, studies about spatial association between concentrations of ambient pollutants and mortality in China are rare. To investigate the spatial variation of association between concentrations of particulate matter less than 10 mu m in aerodynamic diameter (PM10), nitrogen dioxide (NO2) and carbon monoxide (CO) and cardiovascular mortality in Beijing, China, we collected data including daily deaths, concentrations of PM10, NO2 and CO, and meteorological factors from 1 January 2009 to 31 December 2010 in all 16 districts of Beijing. Generalized additive model (GAM) and generalized additive mixed model (GAMM) were used to examine the citywide and district-specific effects of PM10, NO2 and CO on cardiovascular mortality. The citywide effect derived from GAMM was lower than that derived from GAM, and the strongest effects were identified for 2-day moving average lag 0-1. The interquartile increases in concentrations of PM10, NO2 and CO were associated with 2.46 (95% confidence interval (CI), 1.22-3.72), 4.11 (95% CI, 2.82-5.42) and 2.23 (95% CI, 1.14-3.33) percentage increases in daily cardiovascular mortality by GAMM, respectively. The relative risk of each district compared with reference district was generally statistically significant. The death risk associated with air pollutants varies across different geographic districts in Beijing. The data indicate that the risk is high in suburban areas and rural counties. We found significant and spatially varied adverse effects of air pollution on cardiovascular deaths across the rural and urban areas in Beijing.
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| 10. |
- Luo, Kai, et al.
(author)
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Acute Effects of Nitrogen Dioxide on Cardiovascular Mortality in Beijing : An Exploration of Spatial Heterogeneity and the District-specific Predictors
- 2016
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In: Scientific Reports. - London, United Kingdom : Nature Publishing Group. - 2045-2322. ; 6:2
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Journal article (peer-reviewed)abstract
- The exploration of spatial variation and predictors of the effects of nitrogen dioxide (NO2) on fatal health outcomes is still sparse. In a multilevel case-crossover study in Beijing, China, we used mixed Cox proportional hazard model to examine the citywide effects and conditional logistic regression to evaluate the district-specific effects of NO2 on cardiovascular mortality. District-specific predictors that could be related to the spatial pattern of NO2 effects were examined by robust regression models. We found that a 10 μg/m(3) increase in daily mean NO2 concentration was associated with a 1.89% [95% confidence interval (CI): 1.33-2.45%], 2.07% (95% CI: 1.23-2.91%) and 1.95% (95% CI: 1.16-2.72%) increase in daily total cardiovascular (lag03), cerebrovascular (lag03) and ischemic heart disease (lag02) mortality, respectively. For spatial variation of NO2 effects across 16 districts, significant effects were only observed in 5, 4 and 2 districts for the above three outcomes, respectively. Generally, NO2 was likely having greater adverse effects on districts with larger population, higher consumption of coal and more civilian vehicles. Our results suggested independent and spatially varied effects of NO2 on total and subcategory cardiovascular mortalities. The identification of districts with higher risk can provide important insights for reducing NO2 related health hazards.
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